microtech ii™ applied rooftop unit controller...6 om-137-2 getting started the microtech ii...

MicroTech II™Applied Rooftop Unit Controller

Discharge Air Control (DAC)

• Used with McQuay models: RPS, RFS, RCS, RPR, RFR, RDT, RPE, RDE, RCE, RDS, RAR and RAH

Operation Manual OM137-2

Group: Applied Systems

Part Number: OM137

Date: March 2004

Discharge CoolingDisch Air= 55.0°FClg Capacity= 50%Eff Clg Spt= 55°F

© 2004 McQuay International

ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Using the Keypad/Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Menu Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Display Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Password Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Keypad Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Keypad/Display Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Keypad/Display Menu Reference . . . . . . . . . . . . . . . . . . . . . . . . . 13System Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Airflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Schedules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Setup/Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Active Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Previous Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Remote Keypad Display Option . . . . . . . . . . . . . . . . . . . . . . 49

Operator’s Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Determining Unit Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Unit Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Clg Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Htg Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Clg Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50Htg Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Auto/Manual Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Ctrl Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Appl Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Occupancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53Occ Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53OccSrc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Tenant Override . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55Emergency Override . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Setting Controller Date and Time . . . . . . . . . . . . . . . . . . . . . 56Internal Daily Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . 56Holiday Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58One Event Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Optimal Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58External Time Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Network Time Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Alarm Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59About Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Remote Alarm Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . 60Local Alarm Indication (Keypad/Display) . . . . . . . . . . . . . . . 61Remote Alarm Clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Configuring Remote Alarm Output. . . . . . . . . . . . . . . . . . . . . 63

Unit Configuration/Service Parameters . . . . . . . . . . . . . . . . . . . . . 64Calibrate Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64Zone (Space) Temperature Sensor . . . . . . . . . . . . . . . . . . . 64Miscellaneous Service Parameters . . . . . . . . . . . . . . . . . . . 65Control Timer Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66Manual Output Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Description of Operation . . . . . . . . . . . . . . . . . . . . . . . . 70Operating States and Sequences . . . . . . . . . . . . . . . . . . . . . . . . . 70

About Operating States . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70Operating State Descriptions . . . . . . . . . . . . . . . . . . . . . . . . 71Operating State Sequence Chart . . . . . . . . . . . . . . . . . . . . . 73

Startup Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74Before Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74Fan Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Heat/Cool Changeover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

0-30% Outdoor Air Damper Control . . . . . . . . . . . . . . . . . . . . . . . 77Minimum Ventilation Control . . . . . . . . . . . . . . . . . . . . . . . . . 77

100% Outdoor Air Damper Control . . . . . . . . . . . . . . . . . . . . . . . . 77

Economizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78Economizer Changeover Method . . . . . . . . . . . . . . . . . . . . . 79Minimum Ventilation Control . . . . . . . . . . . . . . . . . . . . . . . . . 79

Cooling: Multistage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Low Ambient Cooling Lockout . . . . . . . . . . . . . . . . . . . . . . . . 87Compressor Staging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87Air-cooled Condenser Fan Control . . . . . . . . . . . . . . . . . . . . 90Evaporative Condenser Fan Control . . . . . . . . . . . . . . . . . . . 91Circuit Pumpdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Cooling: Modulating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Heating: One Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93Morning Warm-up Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 94High Ambient Heating Lockout . . . . . . . . . . . . . . . . . . . . . . . 94

Heating: Multistage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94Morning Warm-up Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 95High Ambient Heating Lockout . . . . . . . . . . . . . . . . . . . . . . . 96Discharge Air Low Limit Control . . . . . . . . . . . . . . . . . . . . . . 96

Heating: Modulating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96Morning Warm-up Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 98High Ambient Heating Lockout . . . . . . . . . . . . . . . . . . . . . . . 99Discharge Air Low Limit Control . . . . . . . . . . . . . . . . . . . . . . 99

Discharge Set Point Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100Cooling Discharge Set Point Reset . . . . . . . . . . . . . . . . . . . 100Heating Discharge Set Point Reset . . . . . . . . . . . . . . . . . . . 103

Energy Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105Enthalpy Wheel Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106Exhaust Fan Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107Energy Recovery Bypass Damper Control . . . . . . . . . . . . . 108

Discharge Fan Capacity Control . . . . . . . . . . . . . . . . . . . . . . . . . 108Duct Static Pressure Control . . . . . . . . . . . . . . . . . . . . . . . . 108Discharge Fan Direct Position Control . . . . . . . . . . . . . . . . 108Post Heat Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Return Fan Capacity Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109VaneTrol Fan Tracking Control . . . . . . . . . . . . . . . . . . . . . . 109Automatic Discharge/Return Fan Balancing Procedure . . . 110Direct Building Static Pressure Control . . . . . . . . . . . . . . . . 112Return Fan Direct Position Control . . . . . . . . . . . . . . . . . . . 112SAF/RAF Differential OA Reset . . . . . . . . . . . . . . . . . . . . . 112

Propeller Exhaust Fan Control . . . . . . . . . . . . . . . . . . . . . . . . . . 113Direct Building Static Pressure Control . . . . . . . . . . . . . . . . 113Exhaust Fan Direct Position Control . . . . . . . . . . . . . . . . . . 113

Unoccupied Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114Unoccupied Heating (Night Setback) . . . . . . . . . . . . . . . . . 114Unoccupied Cooling (Night Setup) . . . . . . . . . . . . . . . . . . . 114Purge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115Special Space Sensor Failure Operation . . . . . . . . . . . . . . 115

Alarm Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

MicroTech II DDC Features . . . . . . . . . . . . . . . . . . . . . 126Direct PID Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126Cascaded PID Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126PID Control Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127Proportional Band and Integral Time . . . . . . . . . . . . . . . . . . 127

Adjusting PID Control Parameters . . . . . . . . . . . . . . . . . . . . . . . . 127Correcting System Instability (“Hunting”) . . . . . . . . . . . . . . . 127Correcting System “Sluggishness” . . . . . . . . . . . . . . . . . . . 128PRAC Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

2

Software Identification and Configuration . . . . . . . . . .129Software Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129Main Control Board (MCB) Configuration . . . . . . . . . . . . . . . . . . 130

Main Control Board (MCB) Data Archiving . . . . . . . . . . . . . . . . . 131Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

McQuay, MicroTech II, and RoofPak are registered trademarks of McQuay International.Microsoft is a registered trademark of Microsoft Corporation.

Windows is a trademark of Microsoft Corporation.Copyright © 2003 McQuay International. All rights reserved throughout the world.

Document Number: OM-137-2Revision: April 2003

OM-137-2 3

IntroductionThis manual provides information regarding the MicroTech II control system used in the McQuay RoofPak applied rooftop unit product line. It specifically describes the sequences of operation and programmable options for units with factory equipped discharge air control (DAC) software. It also includes information regarding how to use the keypad/display to enter and display data.For information regarding MicroTech II components, input/output configurations, field wiring options and requirements, and service procedures, refer to IM696, MicroTech II Applied Rooftop Unit Controller. For installation and startup instructions and general information regarding a particular rooftop unit, refer to the applicable

model-specific installation and maintenance manual (refer to Table 1).

Table 1: Model-Specific Rooftop Unit Installation Literature

Rooftop Unit Model

Installation & Maintenance Data Bulletin

Number

RPS/RDT/RFS/RCS 015-075C (with Scroll Compressors) IM 738

RPS/RDT/RFS/RCS 070-135C (with Reciprocating Compressors) IM 739

RPE/RDE/RCE (Evaporative Condenser Units) IM 791

RDS & RAH IM 487-3

NOTICEThis equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with this instruction manual, may cause interference to radio communications. It has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user is required to correct the interference at his own expense. McQuay International disclaims any liability resulting from any interference or for the correction thereof.

WARNINGElectric shock hazard. Can cause personal injury or equipment damage.

This equipment must be properly grounded. Connections and service to the MicroTech II control panel must be performed only by personnel that are knowledgeable in the operation of the equipment being controlled.

WARNINGExcessive moisture in the control panel can cause hazardous working conditions and improper equipment operation.

When servicing this equipment during rainy weather, the electrical components in the main control panel must be protected from the rain.

4 OM-137-2

CAUTIONExtreme temperature hazard. Can cause damage to system components.

The MicroTech II controller is designed to operate in ambient temperatures from -20°F to 125°F. It can be stored in ambient temperatures from -40°F to 140°F. It is designed to be stored and operated in relative humidity up to 95% (non-condensing).

CAUTIONStatic sensitive components. A static discharge while handling electronic circuit boards can cause damage to the components.

Discharge any static electrical charge by touching the bare metal inside the main control panel before per-forming any service work. Never unplug any cables, circuit board terminal blocks, relay modules, or power plugs while power is applied to the panel.

WARNING To avoid possible unit damage, Compressor pumpdown is required before removing power to the controller.

OM-137-2 5

Getting StartedThe MicroTech II Applied Rooftop Unit Controller is a self-contained device that is capable of complete, stand-alone operation. Information in the controller can be displayed and modified by using the keypad/display in the unit main control panel.The following sections describe how to use the keypad/display.

Using the Keypad/DisplayThe keypad/display, shown in Figure 1, is provided with all MicroTech II Applied Rooftop Unit Controllers on these units. With the keypad/display, operating conditions, system alarms, control parameters, and schedules can be monitored. After password entry, set points, parameters, and schedules can be edited.

Menu StructureThe keypad accessible information in the MicroTech II controller is organized in a menu structure to provide quick access. As shown in Figure 2 on page 7, this structure contains 1 main menu and a string of 53 sub-menus. Each sub-menu is made up of one or more menu items. The string of 53 sub-menus is divided into 8 “categories.” The main menu has eight items within it that “point” or provide a “bookmark” to the first sub-menu within the respective category. The eight categories in the main menu are “System Summary”, “Airflow”, “Temperature”, “Humidity”, “Schedules”, “Setup/Service”, “Active Alarms” and “Previous Alarms.” The name of each category generally describes the basic purpose of the menus in the particular group. Complete information regarding the contents of each sub-menu is included in “Keypad/Display Menu Reference” on page 13.

Note: Only those menus applicable to units with a 1 or 3 in position 1 of the “Software Configuration Code” are described in this manual. Refer to OM138 for all others.

A number of menus and menu items that appear on the unit keypad/display are conditional and may not apply to a

specific unit depending on the unit software configuration. The unit software configuration is defined by a “Software Configuration Code” shown on a label located on the backside of the door upon which the keypad/display is mounted. The Software Configuration Code can also be display via the six menu items in the Config Code menu on the unit keypad\display (refer to“Software Identification and Configuration” on page 129). The menus and menu items that are shaded in Figure 2 are conditional. A menu or menu item that is conditional includes a reference to the position in the “Software Configuration Code” upon which its applicability depends. For example, the Duct Pressure menu in Figure 2 includes a notation [14=1 or 2]. This notation means that the Duct Pressure menu (and all its menu items) applied to the specific unit only if position 14 in its “Software Configuration Code” is a 1 or a 2. Otherwise, the menu or menu item is not applicable to the unit and does not affect its operation.

Figure 1: Keypad/display

Discharge CoolingDisch Air= 55.0°FClg Capacity= 50%Eff Clg Spt= 55°F

6 OM-137-2

Figure 2: Keypad Accessible Menu Structure

Sub Menus

Syste

m

12

3

UnitS

tatus

= __

___

A

Clg C

apac

ity=

xxx%

Htg C

apac

ity=

xxx%

Clg S

tatus

= __

___

Htg S

tatus

= __

___

Ctrl M

ode=

Off

Appl

Mode

= He

at/Co

olVA

V Ou

tput=

____

_[14

=1 or

2]

Occu

panc

y

Occu

panc

y= __

___

Occ M

ode=

Auto

OccS

rc= __

___

Tnt O

vrd=

0 min

Emer

g Ove

rride

= No

rm

Temp

eratu

res

Contr

ol Te

mp=

xxx.x

°FDi

sch A

ir= xx

x.x°F

Retur

n Air=

xxx.x

°F[1=

1 or 2

]Sp

ace T

emp=

xxx.x

°FOA

Tem

p= xx

x.x°F

Ent F

an=

xxx.x

°F[9=

2,3,4,

6,7,A

or B

]

Airflo

w Su

mmar

y

Flow

Statu

s= __

___

Disc

h Fan

= __

___

RF/E

F Fa

n= __

___

[15=0

,1,2 o

r 4]

Fan O

pera

tion=

____

_

Duct

Pres

sure

[14=1

or 2]

Duct

Pres

s= x.

xx"W

CDu

ctSP

Spt=

1.00

"WC

DSP

Db=

0.08"

WC

Disc

h Fan

Cap

= xx

x%RF

/EF

Fan C

ap=

xxx%

Bldg

Pre

ssur

e[15

=1,2

or 4]

Zone

Coo

ling

Contr

ol Te

mp=

xxx.x

°FCl

g Cap

acity

= xx

x%Ef

f Clg

Spt=

xxx.x

°FOc

c Clg

Spt=

75.0°

FCl

g Dea

dban

d= 2.

0°F

CtrlT

emp S

rc= R

eturn

Spac

e Tem

p= xx

x.x°F

Unoc

cClg

Spt=

85.0°

FUn

occC

lgDiff=

3.0°

FCl

g Stat

us=

____

_OA

TClg

Lock

= 55

°FOA

TLoc

k Diff=

1°F

Bldg

Pre

ss=

x.xx"W

CBl

dgSP

Spt=

0.05

0"W

CBS

P Db

= 0.0

10"W

CRF

/EF

Fan C

ap=

xxx%

Zone

Hea

ting

Contr

ol Te

mp=

xxx.x

°FHt

g Cap

acity

= xx

x%Ef

f Htg

Spt=

xxx.x

°FOc

c Htg

Spt=

70.0°

FHt

g Dea

dban

d= 2.

0°F

CtrlT

emp S

rc= R

eturn

Spac

e Tem

p= xx

x.x°F

Unoc

cHtg

Spt=

55.0°

FUn

occH

tgDiff=

3.0°

FHt

g Stat

us=

____

_OA

THtg

Lock

= 55

°FOA

TLoc

k Diff=

1°F

Disc

harg

e Coo

ling

Disc

h Air=

xxx.x

°FCl

g Cap

acity

= xx

x%Ef

f Clg

Spt=

xxx.x

°FDA

T Cl

g Spt=

55.0°

F[1=

1 or 3

]Cl

g Db=

2.0°

FMi

n Clg

Spt=

55.0°

FMa

x Clg

Spt=

65.0°

FCl

g Res

et= N

one

[1=1 o

r 3]

Min C

lg Sp

t@=

0[1=

1 or 3

]Ma

x Clg

Spt@

= 10

0[1=

1 or 3

]

Disc

harg

e Hea

ting

Disc

h Air=

xxx.x

°FHt

g Cap

acity

= xx

x%Ef

f Htg

Spt=

xxx.x

°FDA

T Ht

g Spt=

100.0

°F[1=

1 or 3

]Ht

g Db=

2.0°

F

Min H

tg Sp

t= 60

.0°F

Max H

tg Sp

t= 12

0.0°F

Htg R

eset=

Non

e[1=

1 or 3

]Mi

n Htg

Spt@

= 0

[1=1 o

r 3]

Max H

tg Sp

t@=

100

[1=1 o

r 3]

Min D

AT C

trl= Y

es

OA D

ampe

rEn

ergy

Rec

over

y[19

=1 or

2]

RF/E

F Fa

n Cap

= xx

x%EF

Min

Cap=

5%En

ergy

Rec

= Ye

s

CANC

EL

BACK

OA D

ampe

r Pos

= xx

x%[7=

1,2,3,

4,A,B

or C

]Ef

f Min

OA P

os=

xxx%

[7=3 o

r C]

OA F

low=

xxxx

xCFM

[8>0]

OA A

mbien

t= __

___

[7=3 o

r C]

MinO

A Ty

pe=

None

[7=3 o

r C]

Desig

nFlow

= No

[8>0]

MinO

A Po

s= 10

%[1=

1,3,A

or C

]Mi

nOA

Flow=

2000

CFM

[8>0]

MinO

A @

Max S

ig= 50

%[7=

3 or C

]Mi

n Sign

al= 0%

[7=3 o

r C]

Max S

ignal=

100%

[7=3 o

r C]

MinO

ARes

etMax

= 50

%[7=

3 or C

]Ma

x Fan

Diff=

50%

[15=1

or 2]

Min F

an D

iff= 20

%[15

=1 or

2]Re

set T

Limi

t= 0°

F[7=

3 or C

]Ec

onCh

govr=

Enth

alpy

[7=3 o

r C]

Econ

Chgo

vrT=

60°F

[7=3 o

r C]

Econ

Chgo

vrDiff=

1°F

[7=3 o

r C]

Max P

urge

= 60

min

[7=3 o

r C]

OA T

emp=

xxx.x

°F

Keyp

ad K

ey D

efin

ition

s

Mov

e D

ispl

ay L

eft

Mov

e Ed

it C

urso

r Lef

t

SAVE

ENTE

R

CANC

EL

BACK

ALAR

MAL

ARM

CLEA

R

Mov

e D

ispl

ay R

ight

Mov

e Ed

it C

urso

r Rig

htM

ove

Dis

play

Up

Incr

emen

t Adj

usta

ble

Para

met

erM

ove

Dis

play

Dow

nD

ecre

men

t Adj

usta

ble

Para

met

er

Back

up T

o Pr

evio

us M

enu

Can

cel E

ditin

g C

omm

and

Sele

ct M

enu

Save

Edi

ted

Para

met

erD

ispl

ay A

ctiv

e Al

arm

Cle

ar A

ctiv

e Al

arm

ER D

AT=

xxx.x

°FER

Exh

T= xx

x.x°F

Syst

em S

umm

ary

Airfl

ow

Hum

idity

Sche

dule

sSe

tup/

Serv

ice

Activ

e Al

arm

sPr

evio

us A

larm

s

1 2 3 4 5 6 7

Tem

pera

ture

s

8

Mai

n M

enu

Evap

Con

dens

ing[6>

0]

VFD

Spee

d= xx

x%Su

mp T

emp=

xxx.x

°FMi

n Fan

Spe

ed=

25%

Min S

umpT

= 75

°FMa

x Sum

pT=

85°F

Stag

e Tim

e= 10

Min

A

MinD

AT Li

mit=

55.0°

F[1=

0 or 2

]

Sump

Dum

p Spt=

35°F

OM-137-2 7

Figure 2: Keypad Accessible Menu Structure (Continued)

Comp

Brd

1 ID

= __

___

[2=1]

Daily

Sch

edule5

6

Mon=

00:00

- 00

:00Tu

e= 00

:00 -

00:00

Wed

= 00

:00 -

00:00

Thu=

00:00

- 00

:00Fr

i= 00

:00 -

00:00

Sat=

00:00

- 00

:00Su

n= 00

:00 -

00:00

Hol=

00:00

- 00

:00

One E

vent

Sche

dule

Beg=

mmm

dd@

hh:m

mEn

d= m

mm dd

@hh

:mm

Optim

al St

art

Spac

e Tem

p= xx

x.x°F

Optim

al St

art=

No

Auto

Upda

te= Y

esHt

g Rate

= 0.4

°F/m

inHt

g OAT

= 35

°F

2nd P

Sen

sor=

Non

e[14

=1,2

or 15

=1,2

or 4]

DF C

apCt

rl= D

uctP

res

[14=1

or 2]

Remo

te DF

Cap

= 25

%[14

=1 or

2]RF

/EF

Ctrl=

Tra

cking

[15=1

,2 or

4]Re

m RF

/EF

Cap=

25%

[15=1

,2 or

4]En

g Unit

s= E

nglis

h

Pass

word

s

Timeo

ut= 15

min

Clea

r Alar

m= N

o

Oper

ating

Hou

rs

Fan=

xxxx

x hr

Mech

Coo

l= xx

xxx h

r[2>

0]Co

mp 1=

xxxx

x hr

[2=1

]Co

mp 2=

xxxx

x hr

[2=1

]Co

mp 3=

xxxx

x hr

[2=1

]Co

mp 4=

xxxx

x hr

[2=1

]

Heati

ng=

xxxx

x hr

[9>0

]Ec

onom

izer=

xxxx

x hr

[7=3 o

r C]

Tnt O

vrd=

xxxx

x hr

Duct

Stati

c P S

etup

[14=1

or 2]

DSP

Prop

bd=

6.0"W

CDS

P Int

Time=

40 se

cDS

P Pe

riod=

10 se

c

Timer

Sett

ings

Servi

ce=

0 min

Recir

culat

e= 3

min

[1=0 o

r 1]

Low

DAT=

3 mi

nMa

x MW

U= 90

min

[1=0 o

r 1]

Tnt O

vrd=

120 m

inSt

art In

it= 18

0 sec

Post

Heat=

0 mi

n[14

=1 or

2]

Time=

hh:m

m:ss

Day=

day

Date=

dd-m

mm-yy

yy

Fan T

rack

ing[14

=1 or

2 &

15=1

or 2]

DF M

ax w

/oExh

= 10

0%

Fan B

alanc

e[14

=1 or

2 &

15=1

or 2]

Fan B

alanc

e= O

ffSe

t Max

w/o

Exh=

No

Set M

in w/

o Exh

= No

Set M

ax w

/ Exh

= No

Set M

in w/

Exh

= No

Rem

RF/E

F Ca

p= 25

%

Holid

ay S

ched

ule

Hol 1

=mmm

dd-m

mmdd

Hol 2

=mmm

dd-m

mmdd

Hol 3

=mmm

dd-m

mmdd

Hol 1

3=mm

mdd-

mmmd

dHo

l 14=

mmmd

d-mm

mdd

Hol 1

5=mm

mdd-

mmmd

dHo

l 16=

mmmd

d-mm

mdd

Htg Z

ero O

AT=

0°F

Clg R

ate=

0.4°F

/min

Clg O

AT=

85°F

Clg Z

ero O

AT=

100°

F

Unit C

onfig

urati

on

AHU

ID=

____

_

Calib

rate

Mode

= No

Spac

e Sen

sor=

Yes

EFT

Sens

or=

No

ERec

over

y= xx

xxx h

r[19

=1 or

2]

Time/D

ate

RF@

DFMa

x w/oE

x=95

%DF

Min

w/oE

xh=

20%

RF@

DFMi

n w/oE

x=15

%DF

Max

w/E

xh=

100%

RF@

DFMa

x w/E

x=60

%DF

Min

w/Ex

h= 20

%RF

@DF

Min w

/Ex=

10%

BEc

onom

izer S

etup

[7=3 o

r C]

Clg P

ropb

d= 30

°FCl

g IntT

ime=

60 se

cCl

g Per

iod=

30 se

c

Comp

ress

or S

etup

[2=1 &

3<8]

Lead

Circ

uit=

#1Co

mp C

trl= C

ross

Circ

Clg M

ethod

= Av

erag

eCo

nd F

an1 S

pt= 0°

FCo

nd F

an2 S

pt= 55

°FCo

nd F

an3 S

pt= 65

°FCo

nd F

an4 S

pt= 75

°FCo

nd F

an D

iff= 5°

FSt

age T

ime=

5 mi

n

Desig

nFlow

Setu

p[8>

0]

Wait

Tim

e= 30

sec

Modb

and=

50%

Max S

tep=

5.0%

Dead

band

= 6.0

%LH

Flow

= xx

x.xx%

RH F

low=

xxx.x

x%

Bldg

Stat

ic P

Setup

[15=1

,2 or

4]

BSP

Prop

bd=

1.0"W

CBS

P Int

Time=

10 se

cBS

P Pe

riod=

5 se

c

Chille

d Wate

r Setu

p[2=

2 or A

]

Clg P

ropb

d= 30

°FCl

g IntT

ime=

60 se

cCl

g Per

iod=

30 se

c

Stag

e Tim

e= 5

min

A Sub Menus (Continued)

Exha

ust F

an S

etup

[15=4

]

Min E

xh F

an C

ap=

25%

Min O

A Dm

pr=

5%Mi

n DF

Cap=

10%

Min S

trt T

ime=

120 s

ecMi

n Stop

Tim

e= 12

0 sec

Feed

back

= 3 W

ireFe

edba

ck=

3 Wire

AI11

Refe

renc

e= N

o

Comp

5= xx

xxx h

r [3

=6]

Comp

6= xx

xxx h

r [3

=6]

PRAC

= No

PRAC

= No

Zone

Tem

p Setu

p[1=

0 or 2

]

Clg I

ntTim

e= 70

0 sec

Perio

d= 60

sec

Clg P

ropb

d= 8.

0°F

Spt S

ource

= Ke

ypad

Htg P

ropb

d= 12

.0°F

Htg I

ntTim

e= 50

0 sec

PRAC

= No

PRAC

= No

4

Dehu

midif

icatio

n[1=

0 or 2

]

Dehu

m St

atus=

____

_Re

l Hum

idity=

xxx%

Dew

Point

= xx

.x°F

Dehu

m Me

thod=

None

RH S

etpoin

t= 50

%De

wPoin

t Spt=

50°F

DewP

nt Db

= 2°

FRH

Db=

2%

Confi

gura

tion C

ode

Pos #

1-4=

x.xx

xPo

s # 5-

8= x.

xxx

Pos #

9-12

= x.x

xxPo

s # 13

-16=

x.xx

xPo

s # 17

-20=

x.xx

xPo

s # 21

-22=

x.x

Comp

Brd

2 ID

= __

___

[2=1,

& 3<

8]

El H

t Brd

ID=

____

_[9=

2]ER

Brd

ID=

____

_[19

=1 or

2]

GenC

ond B

rd ID

= __

__[3=

8]

8 OM-137-2

Figure 2: Keypad Accessible Menu Structure (Continued)

Activ

e Alar

m 1

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Manu

al Co

ntrol

Manu

al Co

ntrol=

No

Disc

harg

e Fan

= Of

fRF

/EF

Fan=

Off

[15=0

,1,2 o

r 4]

Fan O

pera

tion=

Off

Alar

m= N

orma

lOA

Dam

per=

Auto

[7>0]

Mod C

oolin

g= A

uto[2=

2 or A

]Mo

d Hea

ting=

Auto

[9=1,5

or C

]VA

V Ou

tput=

Heat

[14=1

or 2]

Disc

h Van

es=

Auto

[14=1

]

Free

ze=

Fast

[2=2,A

or 9=

1,5 or

C]

Smok

e= F

ast

OAT

Sens

or=

Fast

[1=3]

Spac

e Sen

sor=

Fas

t[1=

2 or 3

]Re

turn S

enso

r= F

ast

[1=0 o

r 1]

Disc

h Sen

sor=

Fas

t

BEn

ergy

Rec

over

y Setu

p[19

=1 or

2]

Min E

xhT

Diff=

2°F

Max E

xhT

Diff=

6°F

Stag

e Tim

e= 5

min

RF/E

F Va

nes=

Auto

[15=1

]Di

sch V

FD=

Auto

[14=2

]RF

/EF

VFD=

Auto

[15=2

]

Alar

m Ou

t Fau

lts

Duct

Hi Li

mit=

Fas

t[14

=1 or

2]Hi

Retu

rn T

emp=

Fas

t[1=

0 or 1

]Hi

Disc

h Tem

p= F

ast

Lo D

isch T

emp=

Fas

tFa

n Fail

= Fa

stOA

Dmp

r Stuc

k= F

ast

[1=2 o

r 3]

Free

ze=

Slow

[2=2,A

or 9=

1,5 or

C]

OAT

Sens

or=

Slow

Spac

e Sen

sor=

Slow

[1=0,1

or 3]

Retur

n Sen

sor=

Slow

[1=0 o

r 1]

Ent F

an S

ens=

Slow

[18=1

]Lo

Airfl

ow=

Slow

[9=2,3

,4,6,7

,A or

B]

Alar

m Ou

t Pro

blems

Heat

Fail=

Slow

[9=3,4

,6,A

or B

]Fa

n Retr

y= S

low[14

=2]

Hi P

ress

-Ckt1

= Sl

ow[3<

8]Hi

Pre

ss-C

kt2=

Slow

[3<8]

Lo P

ress

-Ckt1

= Sl

ow[3<

8]Lo

Pre

ss-C

kt2=

Slow

[3<8]

Fros

t-Ckt1

= Sl

ow[3<

8]Fr

ost-C

kt2=

Slow

[3<8]

Comp

#1 A

lm=

Slow

[3<8]

Comp

#2 A

lm=

Slow

[3<8]

Comp

#3 A

lm=

Slow

[3=4,5

,6 or

7]Co

mp #4

Alm

= Sl

ow[3=

5,6 or

7]

Pump

Down

-Ckt1

= Sl

ow[3<

8]Pu

mpDo

wn-C

kt2=

Slow

[3<8]

Ckt1

Clg E

na=

Slow

[3<8]

Ckt2

Clg E

na=

Slow

[3<8]

GenC

Clg

Ena=

Slow

[3=8]

HtgB

Htg

Ena=

Slow

[9=2]

Ckt1

Comm

Fail

= Sl

ow[3<

8]Ck

t2 Co

mm F

ail=

Slow

[3<8]

Genc

Com

m Fa

il= S

low[3=

8]Ht

gB C

omm

Fail=

Slow

[9=2]

ERec

B Co

mmFa

il= S

low[19

=1 or

2]

Activ

e Alar

m 2

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Activ

e Alar

m 3

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Activ

e Alar

m 4

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

1

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

4

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

5

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

6

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

7

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Prev

ious A

larm

8

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

78

Sub Menus (Continued)

Min O

ff Tim

e= 20

min

Comp

#5 A

lm=

Slow

[3=6]

Comp

#6 A

lm=

Slow

[3=6]

Alar

m Lim

its

Hi D

isch A

lm=

170°

FLo

Disc

h Alm

= 40°

FHi

Retu

rn A

lm= 1

20°F

[1=1 o

r 3]

Heati

ng S

etup

Stag

e Tim

e= 5

min

[9=2,3

,4,6,7

,A or

B]

F&BP

Ctrl=

Ope

nValv

e[9=

1]F&

BP C

hgov

r= 37

°F[9=

1]Ht

g Pro

pbd=

20°F

[9=1,3

,4,5,A

,B or

C]

Htg I

ntTim

e= 12

0 sec

[9=1,3

,4,5,A

,B or

C]

Htg P

eriod

= 60 s

ec[9=

1,3,4,

5,A,B

or C

]

Feed

back

= 3 W

ire[9=

3,4,5,

A,B

or C

]

PRAC

= No

[9=1,3

,4,5,A

,B or

C]

Prev

ious A

larm

3

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Airflo

w Sw

itch=

Off

Dirty

Filte

r= O

ffDi

rty F

nlFltr=

Off

[20=

1]Ck

t1 H/

W=

Off

[3

<8]

Ckt2

H/W

= Of

f

[3<8

]

Alar

m Ou

t War

nings

GenC

H/W

= Of

f [

3=8]

HtgB

H/W

= Of

f

[9=2]

Dehu

m Se

tup[1=

0 or 2

]

Dehu

m Ct

rl= O

ccup

iedMi

nimum

Stag

es= 2

Maxim

um S

tages

= 4

Sens

or Lo

c= R

eturn

DH S

tage T

ime=

10mi

n

Prev

ious A

larm

2

Alar

m Na

meAl

arm

Type

dd-m

mm-yy

hh:m

m:ss

Min E

xh O

n= 12

0 sec

Min E

xh O

ff= 12

0 sec

OM-137-2 9

Display FormatThe information stored in the MicroTech II controller menu structure can be viewed on the 4-line by 20-character LCD display. The current menu is displayed on the top line and up to three menu items are displayed on the next three lines (refer to Figure 3). The item lines contain one or more data fields that convey varying information. A blinking cursor indicates the current item. There is a “navigation” indicator on the right side of the top line while in navigation mode. A symbol indicates there are more items in the menu “above” the current display window. A symbol indicates there are more items in the menu “below” the current display window. A symbol indicates there are more items in the menu “above” and “below” the current display window.

Figure 3: LCD Display Format

Password ProtectionThe MicroTech II controller includes password protection to guard against inadvertent control parameter changes. When an attempt is made to change the value of an adjustable parameter with the keypad, the controller prompts the user to enter either the level 2 (L-2) or level 1 (L-1) password depending on the level required for that particular parameter. The L-2 password is 4545. The L-1 password is 6555.

Note: L-2 has a “higher” level of authority than L-1. The controller prompts for the password by displaying the following:

Figure 4: Password Protection

The password fields initially has values off 5555 in them. The first field is blinking. For example, to change the

password to 4545 and enter the new value, the following procedure is used:

1. Pressing the Down Arrow (-) key one time decrements the first field (blinking) to a value of 4.

2. Pressing the Right Arrow key one time moves the blink-ing cursor to the second field.

3. Again pressing the Right Arrow key one time (the sec-ond field will not be changed in this example) moves the blinking cursor to the third field.

4. Pressing the Down Arrow (-) key one time decrements the third field (now blinking) to a value of 4.

5. Now the four fields should be 4545, the desired pass-word. Pressing the Enter/Save key enters the password.

If the correct password is entered, the display returns to the item to be changed and the changeable item field is blinking waiting to be modified.Password TimeoutOnce the password is entered, the controller allows further changes without prompting the user to enter a password until either the password timer expires or a different password level is required for the particular parameter to be changed. The password timer is adjustable from 2-60 minutes using the Timeout= parameter in the Passwords menu.Clear Alarm PasswordNormally clearing an active alarm does not require a password entry. This is true if the Clear Alarm= item in the Passwords menu is set to “None.” However, if this parameter is set to “L-1” the controller prompts the user to enter the level 1 password before an alarm can be cleared. If this parameter is set to “L-2” the controller prompts the user to enter the level 2 password before an alarm can be cleared. For details regarding alarm clearing, refer to “Keypad/Display Exercises” on page 11.

TemperaturesDisch Air=55.0°FReturn Air=73.5°FSpace Temp=74.5F

Navigation Indicator

Data FieldBlinking Cusor

Menu Line

Item Line

Item Line

Item Line

**Enter L-2 Password

Password= 5555

Blinking Data Field

10 OM-137-2

Keypad FunctionsThe MicroTech II controller keypad consists of 8 pressure sensitive membrane switches. Refer to Figure 1 on page 6. The following are descriptions of these keys and their functions.

Left Arrow Key: Pressing this key changes the displayed menu one menu to the left while navigating within the menu structure. It also changes the field to be edited one field to the left while editing a parameter value.

Right Arrow Key: Pressing this key changes the displayed menu one menu to the right while navigating within the menu structure. It also changes the field to be edited one field to the right while editing a parameter value.

Up Arrow (+) Key: Pressing this key changes the displayed menu or menu item up one menu or menu item while navigating within the menu structure. It also increments a changeable parameter one value while editing.

Down Arrow (-) Key: Pressing this key changes the displayed menu or menu item down one menu or menu item while navigating within the menu structure. It also decrements a changeable parameter one value while editing.

Back/Cancel Key: Pressing this key while navigating within the menu structure changes the displayed menu back to the main menu. While editing a changeable parameter, pressing this key causes the edit session to be terminated and the parameter value reverts to the value it had before beginning the editing session. Pressing this key after having pressed the Alarm key to view an active alarm causes the display to revert to the menu that was in the display prior to pressing the Alarm key. Pressing

this key while at the main menu causes a manual password log off and resets the password timer.

Enter/Save Key:Pressing this key while viewing a menu on the main menu changes the displayed menu to the first menu of the menu group or category associated with that menu. Pressing this key while viewing a changeable menu item places the keypad into “edit” mode. The first changeable field for that parameter begins blinking and the top line of the display is replaced with **Edit Mode, indicating the “edit” mode is activated. Once a parameter is changed in “edit” mode, pressing this key “saves” the new parameter value into memory. When the new parameter value is saved, the changeable field or field stops blinking and the **Edit Mode message disappears from the top line of the display, indicating the keypad is no longer in “edit” mode.

Alarm Key:Pressing this key while the red LED above it on the keypad is on changes the displayed menu to the Active Alarm 1 menu.

Clear Alarm Key: Pressing this key while any of the active alarm menus are being displayed sends a clear command to clear the alarm.

Keypad/Display ExercisesThe following are three exercises that serve as a guide through some typical keypad operations. Note that often there is more than one way to perform an operation.Changing Set PointsIn this exercise, assume that the current cooling discharge air set point is 55°F and is not quite meeting the system cooling requirements. Using the following procedure, the cooling discharge air set point is changed to 53°F.

1. Pressing the Back/Cancel key changes the display back to the main menu if not already there.

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2. Assuming the blinking cursor is positioned on the Sys-tem Summary menu, pressing the Down Arrow (-) key twice changes the cursor position to the Temperature menu.

3. Pressing the Enter/Save key changes the display to the Zone Cooling menu, the first menu in the Temperatures group of menus.

4. Pressing the Right Arrow key twice changes the display to the Discharge Cooling menu. The cursor is positioned on the first item within this menu which is the Disch Air= item.

5. Pressing the Down Arrow (-) key three times moves the display down three items in the menu and positions the cursor on the DAT Clg Spt= item.

6. When the Enter/Save key is pressed and if the password timer has expired since the last time the password was entered, the controller prompts the user to enter a pass-word at this point. The procedure outlined above in “Password Protection” on page 10 must be followed to enter the password. Once the password has been suc-cessfully entered, the display enters the “edit” mode as show below.When the Enter/Save key is pressed and if a password entry is not required, the display simply enters the “edit” mode as shown below.

Note: The Menu Line has been replaced by the “**Edit Mode” indication message, the cursor has disap-peared and the date field to be edited is blinking.

7. Pressing the Down Arrow (-) key once decrements the current DAT Clg Spt= value by a tenth of a degree. Pressing and holding the Down Arrow (-) causes the value to decrement rapidly.

8. When the DAT Clg Spt= parameter is at the desired value (53.0°F in this example), pressing the Enter/Save key stores the new setting and terminates the edit ses-sion.

Note: The data field stops blinking when the new value is recorded and the display leaves the “edit” mode.

Clearing AlarmsIn this exercise, assume that a “fault” alarm exists. This type of alarm shuts down the unit and keeps it off until the alarm is manually cleared. If the conditions that caused the alarm have been corrected, the following procedure is used to clear a fault.

1. Pressing the Alarm key while the red LED on the key-pad is blinking (indicating an active alarm condition) changes the displayed menu to the Active Alarm 1 menu which displays the current highest priority alarm.

2. Pressing the Clear Alarm key sends a clear command to the controller. This clears the alarm and returns the unit to normal operation.

Modifying SchedulesIn this exercise, assume that a change in building occupancy requires the rooftop unit to run from 8:30 a.m. to 5:30 p.m. on Sunday. The current schedule has the unit shut down on Sunday. Using the following procedure, this schedule is changed accordingly. This procedure assumes that the password has previously been entered and the password timer has not expired.

Note: The time schedule and time clock in the MicroTech II controller use “military” time. In this case 5:30 p.m. is equivalent to 17:30 in “military” time.

1. Pressing the Back/Cancel key changes the display to back to the main menu if not already there.

**Edit ModeCooling Capacity=25%Eff Clg Spt=55.0°FDAT Clg Spt=55.0F

Blinking Data Field

Menu Line

Item Line Being Edited

12 OM-137-2

2. Assuming the blinking cursor is positioned on the Sys-tem Summary menu, pressing the Down Arrow (-) key three times changes the cursor position to the Schedules menu.

3. Pressing the Enter/Save key changes the display to the Daily Schedule menu, the first menu in the Schedules group of menus.

4. Pressing the Down Arrow (-) key six times moves the display down six items in the menu and positions the cursor on the Sun= item.

5. When the Enter/Save key is pressed (and if a password entry is not required) the display enters the “edit” mode with the “start hour” data field blinking.

6. Pressing the Up Arrow (+) key once increments the cur-rent “start hour” value by one hour. Pressing and hold-ing the Up Arrow (+) causes the value to increment rapidly.

7. When the “start hour” is at the desired value (08 in this example), pressing the Right Arrow key moves the blinking cursor to the “start minute” field.

8. Pressing the Up Arrow (+) key once increments the cur-rent “start minute” value by one minute. Pressing and holding the Up Arrow (+) causes the value to increment rapidly.

9. When the “start minute” is at the desired value (30 in this example), pressing the Right Arrow key moves the blinking cursor to the “stop hour” field.

10. Pressing the Up Arrow (+) key once increments the cur-rent “stop hour” value by one hour. Pressing and holding the Up Arrow (+) causes the value to increment rapidly.

11. When the “stop hour” is at the desired value (17 in this example), pressing the Right Arrow key moves the blinking cursor to the “stop minute” field.

12. Pressing the Up Arrow (+) key once increments the cur-rent “stop minute” value by one minute. Pressing and holding the Up Arrow (+) causes the value to increment rapidly.

13. When the “stop minute” is at the desired value (30 in this example), pressing the Enter/Save key stores the new Sun= start/stop setting and terminates the edit ses-sion.

Note: The data field stops blinking when the new value is recorded and the display leaves the “edit” mode.

Keypad/Display Menu ReferenceThe following is a brief description of each menu and menu item within the rooftop MicroTech II menu structure. Tables are included which show every menu, item, and field in the menu structure of the program. These menus and items can all be displayed with the keypad/display.

Note: There are a number of instances where the same menu item appears under more that one menu.

System SummaryMenus in the System Summary category contain basic unit operating status and control set point parameters. Table 2 on page 16 lists all menus and items in the System Summary group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the System Summary category menus and items.SystemThe System menu provides a summary of basic unit status and control items.

UnitStatus. UnitStatus= is a status only item which indicates the state in which the unit is currently operating. For detailed information regarding this parameter, refer to “Determining Unit Status” on page 50.

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Clg Capacity. Clg Capacity= is a status only item which indicates the percentage of the unit maximum cooling capacity currently operating.

Htg Capacity. Htg Capacity= is a status only item which indicates the percentage of the unit maximum heating capacity currently operating.

Clg Status. Clg Status= is a status only item which indicates whether or not cooling (economizer and/or mechanical) is currently allowed. If cooling is disabled, the reason is indicated. For detailed information regarding this parameter, refer to “Determining Unit Status” on page 50.

Htg Status. Htg Status= is a status only item which indicates whether or not heating is currently allowed. If heating is disabled, the reason is indicated. For detailed information regarding this parameter, refer to “Determining Unit Status” on page 50.

Ctrl Mode. Ctrl Mode= is an adjustable item which allows the unit to be set for manual off, cooling only, heating only, fan only or auto heating/cooling operation. For detailed information regarding this parameter, refer to “Auto/Manual Operation” on page 52.

Note: If this item is set to “Auto”, then cooling only, heat-ing only, fan only or auto heating/cooling operation is determined by a network signal as indicated by the Appl Mode= item.

Appl Mode. Appl Mode= is a network adjustable item which indicates that the unit is set for network off, cooling only, heating only, fan only or auto heating/cooling operation via a network signal. For detailed information regarding this parameter, refer to “Auto/Manual Operation” on page 52.

Note: This item has no affect on the unit operation unless the Ctrl Mode= item is set to “Auto.”

VAV Output. VAV Output= is a status only item which indicates the status of the VAV Box Output (MCB-B012). This output is provided for field use for interlocking field VAV box operation with the unit heating or cooling operation. This output is OFF (Heat) when the unit is in any heating operating state (including Recirc) and ON (Cool) in

any other operating state. For detailed information regarding this output, refer to “Operating States and Sequences” on page 70 and the “Field Wiring” section of IM696, MicroTech II Applied Rooftop Unit Controller.OccupancyMenus in the Occupancy menu contain status and control items that relate to unit occupied/unoccupied operation.

Occupancy. Occupancy= is a status only item which indicates whether the unit is currently in an occupied, unoccupied, or bypass mode of operation. For detailed information regarding this parameter, refer to “Determining Unit Status” on page 50.

OccMode. OccMode= is an adjustable item which allows the unit to be set for manual occupied or unoccupied operation, automatic operation based on a time schedule input or manual bypass operation. For detailed information regarding this parameter, refer to “Auto/Manual Operation” on page 52.

OccSrc. OccSrc= is status only item which indicates the input source or function that is responsible for setting the Occupancy= parameter to “Occ.” For detailed information regarding this parameter, refer to “Auto/Manual Operation” on page 52.

Tnt Ovrd. Tnt Ovrd= is an adjustable item which indicates the tenant override time remaining when the unit is operating due to override operation. For detailed information regarding this parameter, refer to “Auto/Manual Operation” on page 52.

Emerg Override . Emerg Override= is an adjustable item which provides a means off completely shutting off a unit via a network signal. If this parameter is set to “Off” the unit can not start based on a time clock or any other means. The only way the unit can be started is to change this parameter to “Norm.” For detailed information regarding this parameter, refer to “Auto/Manual Operation” on page 52.TemperaturesMenus in the Temperatures menu contain unit temperature status information.

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Control Temp. Control Temp= is a status only item which displays the current value of the “Control Temperature.” The “Control Temperature” is defined as the temperature input selected by the CtrlTemp Src= parameter in the Zone Cooling or Zone Heating menu. For example, if the CtrlTemp Src= parameter is set to “Return”, then the Control Temp= parameter reads the same value as the Return Air= parameter. For detailed information regarding this parameter, refer to “Heat/Cool Changeover” on page 75.

Disch Air. Disch Air = is a status only item which displays the current temperature reading from the unit discharge air temperature sensor. This sensor is standard on all units.

Return Air. Return Air= is a status only item which displays the current temperature reading from the unit return air temperature sensor. This sensor is standard on all units with return air.

Space Temp. Space Temp= is a status only item which displays the current space (or zone) temperature reading from the optional unit space air temperature sensor input. Refer to “Zone (Space) Temperature Sensor” on page 64.

Note: If an optional space temperature sensor is not installed, the Space Sensor= item in the Unit Con-figuration menu should be set to “No” to disable the alarm function associated with an open circuit at the space temperature sensor input.

OA Temp. OA Temp= is a status only item which displays the current temperature reading from the unit mounted outdoor air temperature sensor. This sensor is standard on all units.

Ent Fan. Ent Fan= is a status only item which displays the current temperature reading from the unit entering fan air temperature sensor. This sensor is standard on all units equipped with gas or electric heat.

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Table 2: System Summary Menus

Menu Name Menu Item Name Factory Default Value Field Number Range

System

UnitStatus - -

Off UnocOff ManOff NetOff SwOff AlmCalib

StartupRecirc

Fan OnlyEcono

CoolingMWU

HeatingMin DAT

UnocEconUnocClgUnocHtgBalanceMan Ctrl

Clg Capacity - - 0-100%Htg Capacity - - 0-100%

Clg Status - -

All ClgEcono

Mech ClgOff AmbOff Alm

Off NoneOff SwOff NetOff Man

Htg Status - -

Htg EnaOff AmbOff Alm


Ctrl Mode Off 1

OffAuto

Heat/CoolHeat OnlyCool OnlyFan Only

Appl Mode Heat/Cool 1

OffHeat/CoolHeat OnlyCool OnlyFan Only

VAV Output - -CoolHeat

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AirflowMenus in the Airflow category contain status and control set point parameters that define the airflow control setup of the unit. Table 3 on page 18 lists all menus and items in the Airflow group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the Airflow category menus and items.Airflow SummaryThe Airflow Summary menu contains status information related to unit airflow, static pressure and fan operation.

Flow Status. Flow Status= is a status only item that indicates whether or not discharge airflow is detected. Airflow status is sensed by a binary input delivered to the controller by a differential pressure switch (PC7).

Disch Fan. Disch Fan= is a status only item which indicates whether or not the controller is commanding the unit discharge fan on.

RF/EF Fan. RF/EF Fan= is a status only item which indicates whether or not the controller is commanding the unit return or exhaust on.

Fan Operation. Fan Operation= is a status only item which indicates the on/off status of the Fan Operation Output (MCB-BO3). For details regarding the Fan Operation Output, refer to the “Field Output Signals” section of IM 696, MicroTech Applied Rooftop Unit Controller.

Duct PressureThe Duct Pressure menu contains parameters that are used to maintain duct static pressure control. For detailed information regarding discharge fan capacity control, refer to “Discharge Fan Capacity Control” on page 108.

Duct Press. Duct Press= is a status only item which indicates the current pressure at the duct static pressure sensor location. When a unit is equipped with two duct static pressure sensors, this item displays the lower of the two sensor readings. Static pressure control is then based on the lower of the two readings.

DuctSP Spt. DuctSP Spt= is an adjustable item which sets the duct static pressure set point used for controlling the discharge air fan inlet vanes or VFD. The inlet vanes or VFD is modulated to maintain the duct static pressure sensor input at this set point.

DSP Db. DSP Db= is an adjustable item which sets a dead band around the DuctSP Spt= parameter in the Duct Static Pressure menu. No duct static pressure control action is taken when the current duct static pressure input is within this dead band.

Disch Fan Cap. Disch Fan Cap= is a status only item which indicates the current discharge fan capacity. 0-100% inlet vane position is indicated if the unit is equipped with discharge air fan variable inlet vanes. 0-100% of VFD maximum speed is indicated if the unit is equipped with a discharge air fan VFD.

RF/EF Fan Cap. RF/EF Fan Cap= is a status only item which indicates the current return or exhaust fan capacity. 0-100% inlet vane position is indicated if the unit is equipped

Occupancy

Occupancy - -Occ

UnoccTnt Ovrd

Occ Mode Auto 1

OccUnocc

Tnt OvrdAuto

OccSrc - -

NoneInt SchedNet SchedOcc Mode

Remote SwTnt Ovrd Time 0 min 1 0 -300 min

Emerg Override Norm 1Norm

Off

Temperatures

Control Temp - - -50 - 250.0 °FDisch Air - - -20 - 275.0 °FReturn Air - - -20 - 175.0 °F

Space Temp - - 10 - 95.0 °FOA Temp - - -50 - 140.0 °FEnt Fan - - -50 - 140.0 °F

Table 2: System Summary Menus (Continued)


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with return or exhaust fan variable inlet vanes. 0-100% of VFD maximum speed is indicated if the unit is equipped with a return or exhaust fan VFD.Bldg PressureThe Bldg Pressure menu contains parameters that are used to maintain building static pressure control when a unit is equipped with a building static pressure sensor for controlling the unit return or exhaust fan capacity. For detailed information regarding building static pressure control, refer to “Direct Building Static Pressure Control” on page 112 or “Exhaust Fan Control” on page 107.

Bldg Press. Bldg Press= is a status only item which indicates the current pressure at the building static pressure sensor location.

BldgSP Spt. BldgSP Spt= is an adjustable item which sets the building static pressure set point used for controlling the return air or exhaust fan inlet vanes or VFD. The inlet vanes or VFD is modulated to maintain the building static pressure sensor input at this set point.

BSP Db. BSP Db= is an adjustable item which sets a dead band around the BldgSP Spt= parameter in the Bldg Static Pressure menu. No building static pressure control action is taken when the current building static pressure input is within this dead band.

RF/EF Fan Cap. RF/EF Fan Cap= is a status only item which indicates the current return or exhaust fan capacity. 0-100% inlet vane position is indicated if the unit is equipped with return or exhaust fan variable inlet vanes. 0-100% of VFD maximum speed is indicated if the unit is equipped with a return or exhaust fan VFD.

TemperatureMenus in the Temperature category contain status and control set point parameters that define the temperature control setup of the unit. Table 4 on page 24 lists all menus and items in the Temperature group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the Temperature category menus and items.Zone CoolingThe Zone Cooling menu primarily contains basic status and control parameters that relate to or affect the unit changeover

into cooling operation. For detailed information regarding unit heating/cooling changeover, refer to “Heat/Cool Changeover” on page 75.

Control Temp. Control Temp= is a status only item which displays the current value of the “Control Temperature.” The “Control Temperature” is defined as the temperature input selected by the CtrlTemp Src= parameter in the Zone Cooling or Zone Heating menu. For example, if the CtrlTemp Src= parameter is set to “Return”, then the Control Temp= parameter reads the same value as the Return Air= parameter. For more information regarding this parameter, refer to“Heat/Cool Changeover” on page 75.

Table 3: Airflow Menus


Airflow Summary

Flow Status - -Flow

NoFlow

Disch Fan - -On

Off

RF/EF Fan - -On

Off

Fan Operation - -On

Off

Duct Pressure

Duct Press - - 0.00 - 4.00 “WC

DuctSP Spt 1.00 “WC 1 0.20 - 4.00 “WC

DSP Db 0.08 “WC 1 0.00 - 0.50 “WC

Disch Fan Cap - - 0 - 100%

RF/EF Fan Cap - - 0 - 100%

Bldg Pressure

Bldg Press - - -0.250 - 0.250 “WC

BldgSP Spt 0.050 “WC 1 -0.250 - 0.250 “WC

BSP Db 0.010 “WC 1 0.001 - 0.100 “WC

RF/EF Fan Cap - - 0 - 100%

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Eff Clg Spt. Eff Clg Spt= is a status only item which indicates the cooling changeover set point currently in effect. When the current value of the Control Temp= parameter rises above this parameter by more than half the Clg Deadband= parameter, cooling operation is enabled. When the current value of the Control Temp= parameter drops below this parameter by more than half the Clg Deadband= parameter cooling operation is disabled. When not being influenced by a network signal, this parameter is set by the controller to same value as the Occ Clg Spt= parameter.

Occ Clg Spt. Occ Clg Spt= is an adjustable item used by the controller to set the Eff Clg Spt= parameter. When not being influenced by a network signal, the Eff Clg Spt= is set to this value.

Clg Deadband. Clg Deadband= is an adjustable item which sets a dead band around the Eff Clg Spt= parameter. For example, if the Eff Clg Spt= parameter is set to 75ºF and the Clg Deadband= parameter is set to 2ºF the dead band around the set point would be from 76.0ºF to 74.0ºF.

CtrlTemp Src. CtrlTemp Src= is an adjustable item which selects the temperature sensor input to be used for the unit heating/cooling changeover decision. For example, if the CtrlTemp Src= parameter is set to “Return”, then the Control Temp= parameter reads the same value as the Return Air= parameter. For detailed information regarding this parameter, refer to “Heat/Cool Changeover” on page 75.



UnoccClg Spt. UnoccClg Spt= is an adjustable item which sets the point at which the unit starts up and provides unoccupied cooling (night setup) during unoccupied periods. For detailed information regarding unoccupied cooling operation, refer to “Unoccupied Cooling (Night Setup)” on page 114.

Note: An optional space temperature sensor is required for unoccupied cooling operation.

UnoccClgDiff. UnoccClgDiff= is an adjustable item which sets a differential below the UnoccClg Spt= parameter. Once activated, unoccupied cooling operation is terminated when the Space Temp= value falls below the UnoccClg Spt= setting by more than this differential.

Clg Status. Clg Status= is a status only item which indicates whether or not cooling (economizer and/or mechanical) is currently allowed. If cooling is disabled, the reason is indicated. For detailed information regarding this parameter, refer to “Determining Unit Status” on page 50.

OATClg Lock. OATComp Lock= is an adjustable item which sets the low outdoor air temperature mechanical cooling lockout point. Mechanical cooling operation is disabled when the outdoor air temperature sensor input falls below this set point.

OATLock Diff. OATLock Diff= is an adjustable item which sets a differential above the OATComp Lock= parameter. Mechanical cooling operation is re-enabled when the outdoor air temperature sensor input rises above the OATComp Lock= value by more than this differential.Zone HeatingThe Zone Heating menu primarily contains basic status and control parameters that relate to or affect the unit changeover into heating operation. For detailed information regarding unit heating/cooling changeover, refer to “Heat/Cool Changeover” on page 75.

Control Temp. Control Temp= is a status only item which displays the current value of the “Control Temperature.” The “Control Temperature” is defined as the temperature input selected by the CtrlTemp Src= parameter in the Zone Cooling or Zone Heating menu. For example, if the CtrlTemp Src= parameter is set to “Return”, then the Control Temp= parameter reads the same value as the Return Air= parameter. For detailed information regarding this parameter, refer to “Heat/Cool Changeover” on page 75.


Eff Htg Spt. Eff Htg Spt= is a status only item which indicates the heating changeover set point currently in effect. When the current value of the Control Temp= parameter, falls below this parameter by more than half the Htg Deadband= parameter, heating operation is enabled. When the current value of the Control Temp= parameter rises above this parameter by more than half the Htg Deadband= parameter heating operation is disabled. When not being influenced by a network signal, this parameter is set by the controller to same value as the Occ Htg Spt= parameter.

Occ HtgSpt. Occ Htg Spt= is an adjustable item used by the controller to set the Eff Htg Spt= parameter. When not being influenced by a network signal, the Eff Htg Spt= is set to this value.

Htg Deadband. Htg Deadband= is an adjustable item which sets a dead band around the Eff Htg Spt= parameter. For example, if the Eff Htg Spt= parameter is set to 70ºF and the Htg Deadband= parameter is set to 2ºF the dead band around the set point would be from 68.0ºF to 72.0ºF.

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CtrlTemp Src. CtrlTemp Src= is an adjustable item which selects the temperature sensor input to be used for the unit heating/cooling changeover decision. For example, if the CtrlTemp Src= parameter is set to “Return”, then the Control Temp= parameter reads the same value as the Return Air= parameter. For detailed information regarding this parameter, refer to “Heat/Cool Changeover” on page 75.



UnoccHtg Spt. UnoccHtg Spt= is an adjustable item which sets the point at which the unit starts up and provides unoccupied heating (night setback) during unoccupied periods. For detailed information regarding unoccupied heating operation, refer to “Unoccupied Heating (Night Setback)” on page 114.

Note: An optional space temperature sensor is required for unoccupied heating operation.

UnoccHtgDiff. UnoccHtgDiff= is an adjustable item which sets a differential above the UnoccHtg Spt= parameter. Once activated, unoccupied heating operation is terminated when the Space Temp= value rises above the UnoccHtg Spt= setting by more than this differential.

Htg Status. Htg Status= is a status only item which indicates whether or not heating is currently allowed. If heating is disabled, the reason is indicated.

OATHtg Lock. OATHtg Lock= is an adjustable item which sets the high outdoor air temperature heating lockout point. Heating operation is disabled when the outdoor air temperature sensor input rises above this set point.

OATLock Diff. OATLock Diff= is an adjustable item which sets a differential below the OATHtg Lock= parameter. Heating operation is re-enabled when the outdoor air temperature sensor input falls below the OATHtg Lock= value by more than this differential.Discharge CoolingThe Discharge Cooling menu contains parameters that relate to or are used to maintain the discharge temperature when the unit is changed over into cooling operation. For detailed information regarding cooling operation, refer to “Heat/Cool Changeover” on page 75, “Economizer” on page 78, “Cooling: Multistage” on page 82, and “Cooling: Modulating” on page 92, as applicable.

Disch Air. Disch Air = is a status only item which displays the current temperature reading from the unit discharge air temperature sensor. This sensor is standard on all units.


Eff Clg Spt. Eff Clg Spt= is a status only item which indicates the cooling discharge air temperature set point currently in effect. When the unit is in a cooling operating state, economizer dampers and/or mechanical cooling capacity are controlled to maintain the unit discharge air temperature input at this set point. The Eff Clg Spt= parameter is either set by the controller to the DAT Clg Spt= value or is set to a value based on the results of a discharge air temperature reset schedule. For detailed information regarding discharge air temperature set point reset, refer to“Cooling Discharge Set Point Reset” on page 100.

DAT Clg Spt. DAT Clg Spt= is an adjustable item used by the controller to set the Eff Clg Spt= parameter. The Eff Clg Spt= parameter is set to this value when it is not being set by a reset schedule. For detailed information regarding discharge air temperature set point reset, refer to “Cooling Discharge Set Point Reset” on page 100.

Clg Db. Clg Db= is an adjustable item which sets a dead band around the Eff Clg Spt= parameter. For example, if the Eff Clg Spt= parameter is set to 55ºF and the Clg Db= parameter is set to 2ºF the dead band around the set point would be from 56.0ºF to 54.0ºF.

Min Clg Spt. Min Clg Spt= is an adjustable item which sets the minimum cooling discharge set point for use with a cooling discharge air temperature set point reset schedule. For detailed information on discharge air temperature set point reset, refer to “Cooling Discharge Set Point Reset” on page 100.

Max Clg Spt. Max Clg Spt= is an adjustable item which sets the maximum cooling discharge set point for use with a cooling discharge air temperature set point reset schedule. For detailed information on discharge air temperature set point reset, refer to “Cooling Discharge Set Point Reset” on page 100.

Clg Reset. Clg Reset= is an adjustable item which is use to activate a cooling discharge air temperature reset schedule and to select the input to be used as a basis for the reset. For detailed information on discharge air temperature set point reset, refer to “Cooling Discharge Set Point Reset” on page 100.

Min Clg Spt@. Min Clg Spt@= is an adjustable item which sets the value of the sensor input, selected with the Clg Reset= parameter, at which the Eff Clg Spt= parameter is reset to the Min Clg Spt= value. For detailed information regarding discharge air temperature set point reset, refer to “Cooling Discharge Set Point Reset” on page 100.

Max Clg Spt@. Max Clg Spt@= is an adjustable item which sets the value of the sensor input, selected with the Clg Reset= parameter, at which the Eff Clg Spt= parameter is reset to the Max Clg Spt= value. For detailed information

20 OM-137-2

regarding discharge air temperature set point reset, refer to “Cooling Discharge Set Point Reset” on page 100.OA DamperThe OA Damper menu contains parameters that relate to or are used to control the unit outdoor air dampers. For detailed information regarding outdoor air damper control, refer to “0-30% Outdoor Air Damper Control” on page 77, “100% Outdoor Air Damper Control” on page 77, or “Economizer” on page 78, as applicable.

OA Damper Pos. OA Damper Pos= is a status only item which indicates the current outdoor air damper position.

Eff Min OA Pos. Eff Min OA Pos= is a status only item which indicates the minimum outdoor air minimum position set point currently in effect. Economizer dampers are controlled to maintain this position whenever minimum ventilation is required. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 77 (0-30% outdoor air units) or “Minimum Ventilation Control” on page 79 (economizer units) as applicable.

OA Flow. OA Flow= is a status only item which indicates the current outdoor airflow based on an optional OA airflow sensor input used when the unit is equipped the DesignFlow OA control feature.

OA Ambient. OA Ambient= is a status only item which indicates whether or not the outdoor air is suitable for free cooling. If it is, “Low” is displayed. If not, “High” is displayed. The free cooling decision can be based on either an enthalpy switch input to the controller or on a dry bulb OA temperature set point. This decision is made via the EconChgovr= parameter. For detailed information regarding economizer changeover operation refer to “Economizer Changeover Method” on page 79.

MinOA Type. MinOA Type= is an adjustable item used to select between a fixed damper position and one of three available methods of automatically resetting the Eff Min OA Pos= parameter.

Note: If the unit is equipped with the DesignFlow outdoor air measuring system and the DesignFlow= param-eter is set to “Yes”, the MinOA Type= parameter automatically reverts to “None”.

For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 77 (0-30% outdoor air units) or “Minimum Ventilation Control” on page 79 (economizer units) as applicable.

DesignFlow. DesignFlow= is an adjustable item used to turn the optional DesignFlow outdoor airflow measuring reset function on and off. This is one of several available methods of automatically resetting the Eff Min OA Pos= parameter. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 79.

MinOA Pos. MinOA Pos= is an adjustable item used by the controller to set the Eff Min OA Pos= parameter. When the Eff Min OA Pos= parameter is not being set based on one of the possible outdoor damper position reset functions, it is set to the MinOA Pos= value. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 77 (0-30% outdoor air units) or “Minimum Ventilation Control” on page 79 (economizer units) as applicable.

MinOA Flow. MinOA Flow= is an adjustable item used by the controller to set the Eff Min OA Pos= parameter when the unit is equipped with the optional DesignFlow OA control feature. When the DesignFlow= parameter is set to “Yes”, the Eff Min OA Pos= is reset to maintain the OA Flow= value at the MinOA Flow= setting. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 79.

MinOA @Max Sig. MinOA @Max Sig= is an adjustable item used to set the Eff Min OA Pos= when the MinOA Type= is set to “Ext mA” or “Ext V.” When either “Ext mA” or “Ext V” is selected, the Eff Min OA Pos= is reset between the MinOA Pos= value and the MinOA @Max Sig= value as a field supplied external current or voltage signal varies between a minimum and maximum value. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 79.

Min Signal. Min Signal= is an adjustable item used to define the minimum value of the field supplied current or voltage signal used to adjust the Eff Min OA Pos= when the MinOA Type= is set to “Ext mA” or “Ext V.” Min Signal= is adjustable from 0-100%. When “Ext mA” is selected, 0-100% refers to 0-100% of 20mA. When “Ext V” is selected, 0-100% refers to 0-100% of 10VDC. For detailed “Minimum Ventilation Control” on page 79.

Max Signal. Max Signal= is an adjustable item used to define the maximum value of the field supplied current or voltage signal used to adjust the Eff Min OA Pos= when the MinOA Type= is set to “Ext mA” or “Ext V.” Max Signal= is adjustable from 0-100%. When “Ext mA” is selected, 0-100% refers to 0-100% of 20mA. When “Ext V” is selected, 0-100% refers to 0-100% of 10VDC. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 79.

MinOA ResetMax. MinOA ResetMax= is an adjustable item which sets a maximum value to which the Eff Min OA Pos= parameter can be set. When reset by any of the possible methods, the Eff Min OA Pos= parameter varies between the Min OA Pos= and the MinOA ResetMax= value. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 79.

Max Fan Diff. Max Fan Diff= is an adjustable item which sets a differential between the discharge and return fan capacities above which the Eff Min OA Pos= parameter is

OM-137-2 21

reset to the MinOA ResetMax= value. As the difference between the discharge and return fan capacities varies between the Min Fan Diff= and Max Fan Diff= values, the Eff Min OA Pos= parameter varies between the MinOA Pos= and the MinOA ResetMax= value. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 79.

Min Fan Diff. Min Fan Diff= is an adjustable item which sets a differential between the discharge and return fan capacities above which the Eff Min OA Pos= parameter begins to be reset from the MinOA Pos= value toward the MinOA ResetMax= value. As the difference between the discharge and return fan capacities varies between the Min Fan Diff= and Max Fan Diff= values, the Eff Min OA Pos= parameter varies between the MinOA Pos= and the MinOA ResetMax= value. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 79.

Reset T Limit. Reset T Limit= is an adjustable item which sets a discharge air temperature low limit which overrides functions that reset the Eff Min OA Pos= parameter if the discharge air temperature gets too cold. For detailed information regarding minimum ventilation control, refer to “Minimum Ventilation Control” on page 79.

EconChgovr. EconChgovr= is an adjustable item which defines the method used to make the economizer changeover decision. When EconChgovr= is set to “Enthalpy”, the economizer changeover decision is based on the enthalpy switch input to the controller. When the switch is closed, the OA Ambient= item indicates “Low” and economizer operation is enabled. When the switch is open, the OA Ambient= item indicates “High” and economizer operation is disabled. When EconChgover= is set to “Dry Bulb”, the economizer changeover decision is based on the outdoor air temperature compared to the EconChgovrT= item. When the outdoor air temperature is below the EconChgovr T= value, the OA Ambient= item indicates “Low” and economizer operation is enabled. When the outdoor air temperature is above the EconChgovr T= by more than the EconChgovrDiff = value, the OA Ambient= item indicates “High” and economizer operation is disabled. For detailed information regarding economizer changeover operation refer to “Economizer Changeover Method” on page 79.

EconChgovrT. EconChgovrT= is an adjustable item used to make the economizer changeover decision when the EconChgovr= parameter is set to “Dry Bulb.” It sets the point below or above which the outdoor air temperature enables or disables economizer operation. If the EconChgovr= parameter is set to “Enthalpy”, this parameter has no effect on the unit operation. For detailed information regarding economizer changeover operation refer to “Economizer Changeover Method” on page 79.

EconChgovrDiff. EconChgovrDiff= is an adjustable item which sets a differential above the EconChgovrT= parameter. When the EconChgovr= parameter is set to “Dry

Bulb”, economizer operation is disabled when the OA Temp= parameter indicates a value above the EconChgovrT= parameter by more than this differential. If the EconChgovr= parameter is set to “Enthalpy”, this parameter has no effect on the unit operation. For detailed information regarding economizer changeover operation refer to “Economizer Changeover Method” on page 79.

Max Purge. Max Purge= is an adjustable item which sets the maximum time prior to occupancy that the units purge feature can be activated. This feature functions only when an optional space (or zone) temperature sensor is installed and when a unit internal time schedule is being used. For detailed information regarding the purge feature, refer to “Purge” on page 115.

OA Temp. OA Temp= displays the current temperature reading from the unit mounted outdoor air temperature sensor. This sensor is standard on all units.Evap CondensingThe Evap Condensing menu contains parameters that are used to control the evaporative condenser on a unit equipped with the evaporative condensing option. For detailed information regarding evaporative condenser control, refer to “Evaporative Condenser Fan Control” on page 91.

VFD Speed. VFD Speed= is a status only item that displays the current VFD speed when the evaporative condenser option includes a VFD to control the first condenser fan on each circuit.

Sump Temp. Sump Temp= is a status only item that displays the current evaporative condenser sump temperature.

Min Fan Speed. Min Fan Speed= is an adjustable item used to set the minimum speed for the VFD speed when the evaporative condenser option includes a VFD to control the first condenser fan on each circuit.

Min SumpT. Min SumpT= is an adjustable item used to set a minimum evaporative condenser sump temperature set point. This value is used to determine when condenser fans are turned off.

Max SumpT. Max SumpT= is an adjustable item used to set a maximum evaporative condenser sump temperature set point. This value is used to determine when condenser fans should be turned on.

Sump Dump Spt. Sump Dump Spt= is an adjustable item used to set a minimum sump temperature. The sump is emptied to prevent freezing if the sump temperature drops below this set point.

Stage Time. Stage Time= is an adjustable item used to set a minimum time period between condenser fan stage changes. Discharge HeatingThe Discharge Heating menu contains parameters that relate to or are used to maintain the discharge temperature when

22 OM-137-2

the unit is changed over into heating operation. For detailed information regarding heating operation, refer to “Heat/Cool Changeover” on page 75, “Heating: One Stage” on page 93, “Heating: Multistage” on page 94, and “Heating: Modulating” on page 96, as applicable.

Disch Air. Disch Air= is a status only item which displays the current temperature reading from the unit discharge air temperature sensor. This sensor is standard on all units.


Eff Htg Spt. Eff Htg Spt= is a status only item which indicates the heating discharge air temperature set point currently in effect. When the unit is in a heating operating state, heating capacity is controlled to maintain the unit discharge air temperature input at this set point (except when unit is equipped with single stage heat). The Eff Htg Spt= parameter is either set by the controller to the DAT Htg Spt= value or based on the results of a discharge air temperature reset schedule. For detailed information regarding discharge air temperature set point reset, refer to “Heating Discharge Set Point Reset” on page 103.

DAT Htg Spt. DAT Htg Spt= is an adjustable item used by the controller to set the Eff Htg Spt= parameter. The Eff Htg Spt= is set to this value when it is not being set by a reset schedule. For detailed information regarding discharge air temperature set point reset, refer to “Heating Discharge Set Point Reset” on page 103.

Htg Db. Htg Db= is an adjustable item which sets a dead band around the Eff Htg Spt= parameter. For example, if the Eff Htg Spt= parameter is set to 100ºF and the Htg Db= parameter is set to 2ºF the dead band around the set point would be from 101.0ºF to 99.0ºF.

Min DAT Ctrl. Min DAT Ctrl= is an adjustable item used to activate or deactivate the low discharge temperature limit function available on units equipped with modulating or multistage heat. For detailed information regarding the low discharge temperature limit function, refer to “Discharge Air Low Limit Control” on page 96 (multistage heat) or “Discharge Air Low Limit Control” on page 99 (modulating heat) as applicable.

Note: The low discharge temperature limit function is not available on units with single stage heat.

Min Htg Spt. Min Htg Spt= is an adjustable item which sets the minimum heating discharge set point for use with a heating discharge air temperature set point reset schedule. For detailed information regarding discharge air temperature set point reset, refer to “Heating Discharge Set Point Reset” on page 103.

Max Htg Spt. Max Htg Spt= is an adjustable item which sets the maximum heating discharge set point for use with a heating discharge air temperature set point reset schedule. For detailed information regarding discharge air temperature set point reset, refer to “Heating Discharge Set Point Reset” on page 103.

Htg Reset. Htg Reset= is an adjustable item which is use to activate a heating discharge air temperature reset schedule and to select the input to be used as a basis for the reset. For detailed information regarding discharge air temperature set point reset, refer to “Heating Discharge Set Point Reset” on page 103.

Min Htg Spt@. Min Htg Spt@= is an adjustable item which sets the value of the sensor input, selected with the Htg Reset= parameter, at which the Eff Htg Spt= parameter is reset to the Min Htg Spt= value. For detailed information regarding discharge air temperature set point reset, refer to “Heating Discharge Set Point Reset” on page 103.

Max Htg Spt@. Max Htg Spt@= is an adjustable item which sets the value of the sensor input, selected with the Htg Reset= parameter, at which the Eff Htg Spt= parameter is reset to the Max Htg Spt= value. For detailed information regarding discharge air temperature set point reset, refer to “Heating Discharge Set Point Reset” on page 103.Energy RecoveryThe Energy Recovery menu contains parameters that relate to or are used to control the enthalpy wheel and exhaust fan when a unit is equipped with an optional energy recovery wheel system. For detailed information regarding the energy recovery control, refer to “Energy Recovery” on page 105.

RF/EF Fan Cap. RF/EF Fan Cap= is a status only item which indicates the current return or exhaust fan capacity. 0-100% inlet vane position is indicated if the unit is equipped with return or exhaust fan variable inlet vanes. 0-100% of VFD maximum speed is indicated if the unit is equipped with a return or exhaust fan VFD.

EF Min Cap. EF Min Cap= is an adjustable item which sets a minimum exhaust fan capacity limit used to start and stop the exhaust fan when a unit is equipped with an optional energy recovery system.

Energy Rec. Energy Rec= is an adjustable item which turns the optional energy recovery system on and off.ER DAT. ER DAT= is status only item which displays the current discharge air temperature leaving the optional energy recovery wheel.ER Exh T. ER Exh T= is status only item which displays the current exhaust air temperature leaving the optional energy recovery wheel. Note: This sensor is present only when the unit is equipped with the energy recovery wheel frost protection option.

OM-137-2 23

Table 4: Temperature Menus


Zone Cooling

Control Temp - - -50 - 250.0 °FClg Capacity - - 0-100%Eff Clg Spt - - 0.0 - 99.0 °F

Occ Clg Spt 75.0 °F 1 0.0 - 99.0 °FClg Deadband 2.0 °F 1 1.0 - 9.9 °F

CtrlTemp Src Return 1ReturnSpaceOAT

Space Temp - - 10 - 95.0 °FUnoccClg Spt 85.0 °F 1 55.0 - 99.0 °FUnoccClgDiff 3.0 °F 1 1.0 - 10.0 °F

Clg Status - -

All ClgEcono

Mech ClgOff AmbOff Alm


OATClg Lock 55 °F 1 0 - 100 °FOATLock Diff 1 °F 1 0 - 10 °F

Zone Heating

Control Temp - - -50 - 250.0 °FHtg Capacity - - 0-100%Eff Htg Spt - - 0.0 - 99.0 °F

Occ Htg Spt 70.0 °F 1 0.0 - 99.0 °FHtg Deadband 2.0 °F 1 1.0 - 9.9 °F

CtrlTemp Src Return 1ReturnSpaceOAT

Space Temp - - 10 - 95.0 °FUnoccHtg Spt 55.0 °F 1 1.0 - 99.0 °FUnoccHtgDiff 3.0 °F 1 1.0 - 10.0 °F

Htg Status -

- Htg EnaOff AmbOff Alm


OATHtg Lock 55 °F 1 0 - 100 °FOATLock Diff 1 °F 1 0 - 10 °F

24 OM-137-2

Discharge Cooling

Disch Air - - -50 - 250.0 °FClg Capacity - - 0-100%Eff Clg Spt - - 40.0 - 100.0 °F

DAT Clg Spt 55.0 °F 1 40.0 - 100.0 °FClg Db 2.0 °F 1 0.0 - 10.0 °F

Min Clg Spt 55.0 °F 1 40.0 - 100.0 °FMax Clg Spt 65.0 °F 1 40.0 - 100.0 °F

Clg Reset None 1

NoneSpaceReturnOATExt V

Ext mAAirflow

Min Clg Spt@ 0 1 0 - 100Max Clg Spt@ 100 1 0 - 100

OA Damper

OA Damper Pos - - 0-100%Eff Min OA Pos - - 0-100%

OA Flow - - 100-50000 CFM

OA Ambient - -LowHigh

MinOA Type None 1

NoneAuto

Ext mAExt V

DesignFlow No 1NoYes

MinOA Pos 10% 1 0-100%MinOA Flow 2000 CFM 1 100-50000 CFM

MinOA @Max Sig 50% 1 0-100%Min Signal 0% 1 0-100%Max Signal 100% 1 0-100%

MinOA ResetMax 50% 1 0-100%Max Fan Diff 50% 1 0-100%Min Fan Diff 20% 1 0-100%Reset T Limit 0°F 1 0-100°F

EconChgovr Enthalpy 1EnthalpyDry Bulb

EconChgovrT 60 °F 1 0 - 99 °FEconChgovrDiff 1 °F 1 0 - 10 °F

Max Purge 60 min 1 0-240 minOA Temp - - -50 - 140.0 °F

Evap Condensing VFD Speed - - 0-100%Sump Temp - - -50 – 140 °F

Min Fan Speed 25% 1 0-99%Min SumpT 75 °F 1 0 – 99 °FMax SumpT 85 °F 1 0 – 99 °F

Sump Dump Spt 35°F 1 0 - 99 °FStage Time 10 min 1 0 – 99 min

Table 4: Temperature Menus (Continued)


OM-137-2 25

SchedulesMenus in the Schedules category contain status and control set point parameters that relate to scheduling the start stop of the unit. Table 5 on page 27 lists all menus and items in the Schedules group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the Schedules category menus and items. For detailed information regarding scheduling the start/stop of the unit, refer to “Auto/Manual Operation” on page 52 and “Scheduling” on page 56.Daily ScheduleThe Daily Schedule menu contains parameters for setting the daily internal start stop schedule for the unit.

Mon. Mon= is an adjustable item which sets one start and one stop time for Monday.

Tue. Tue= is an adjustable item which sets one start and one stop time for Tuesday.

Wed. Wed= is an adjustable item which sets one start and one stop time for Wednesday.

Thu. Thu= is an adjustable item which sets one start and one stop time for Thursday.

Fri. Fri= is an adjustable item which sets one start and one stop time for Friday.

Sat. Sat= is an adjustable item which sets one start and one stop time for Saturday.

Sun. Sun= is an adjustable item which sets one start and one stop time for Sunday.

Hol. Hol= is an adjustable item which sets one start and one stop time for Holidays.One Event ScheduleThe One Event Schedule menu contains parameters for setting a beginning and ending date and time for a one event schedule which overrides the daily internal start stop schedule for that period.

Beg. Beg= is an adjustable item which sets the start date and time for a one event schedule which overrides the daily internal start stop schedule for the period defined by it and the End= parameter.

End. End= is an adjustable item which sets the stop date and time for a one event schedule which overrides the daily internal start stop schedule for the period defined by it and the Beg= parameter.Holiday ScheduleThe Holiday Schedule menu contains parameters for defining up to 16 holiday periods throughout the year. A beginning and ending date is assigned to each holiday period. On each day of the holiday period, the holiday schedule entered in the Daily Schedules menu is used.

Hol 1 through Hol 16. Hol 1= through Hol 16= are adjustable items which are used to define up to 16 holiday periods throughout the calendar year.

Discharge Heating

Disch Air - - -50 - 250.0 °FHtg Capacity - - 0-100%Eff Htg Spt - - 40.0 - 140.0 °F

DAT Htg Spt 100.0 °F 1 40.0 - 140.0 °FHtg Db 2.0 °F 1 0.0 - 10.0 °F

Min DAT Ctrl Yes 1NoYes

Min Htg Spt 60.0 °F 1 40.0 - 140.0 °FMax Htg Spt 120.0 °F 1 40.0 - 140.0 °F

Htg Reset None 1

NoneSpaceReturnOAT

Ext mAExt V

Min Htg Spt@ 0 1 0 - 100Max Htg Spt@ 100 1 0 - 100

Energy Recovery

RF/EF Fan Cap - - 0-100%EF Min Cap 5% 1 0-100%

Energy Rec Yes 1NoYes

ER DAT - - -30.0 - 200.0 °FER ExhT - - -30.0 - 200.0 °F

Table 4: Temperature Menus (Continued)


26 OM-137-2

Optimal StartThe Optimal Start menu contains parameters for adjusting the action of the optimal start function. For detailed information regarding the optimal start function, refer to “Optimal Start” on page 58.



Optimal Start. Optimal Start= is an adjustable item used to turn the optimal start function on and off.

Auto Update. Auto Update= is an adjustable item used to turn on and off a feature included in the optimal start function where the controller “learns” and updates the optimal start parameters automatically based on previous results.

Htg Rate. Htg Rate= is an adjustable item used by the controller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Htg OAT. Htg OAT= is an adjustable item used by the controller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Htg Zero OAT. Htg Zero OAT= is an adjustable item used by the controller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Clg Rate. Clg Rate= is an adjustable item used by the controller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Clg OAT. Clg OAT= is an adjustable item used by the controller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Clg Zero OAT. Clg Zero OAT= is an adjustable item used by the controller in determining the amount time before occupancy to start when the Optimal Start= parameter is set to “On.”

Table 5: Schedules Menus


Daily Schedule

Mon

00 1 00 - 2300 2 00 - 5900 3 00 - 2300 4 00 - 59

Tue Same As Monday Same As Monday Same As MondayWed Same As Monday Same As Monday Same As MondayThu Same As Monday Same As Monday Same As MondayFri Same As Monday Same As Monday Same As MondaySat Same As Monday Same As Monday Same As MondaySun Same As Monday Same As Monday Same As MondayHol Same As Monday Same As Monday Same As Monday

One Event Schedule

Beg N/A

1 Jan-Dec2 01-313 00-234 00-59

End N/A

1 Jan-Dec2 01-313 00-234 00-59

OM-137-2 27

Setup/ServiceMenus in the Setup/Service category contain status and control parameters that relate to the setup and service of the unit. Parameters in these menus are generally the type that are set at the factory and might be adjusted when the equipment is started up and generally do not required further adjustment. Table 6 on page 39 lists all menus and items in the Setup/Service group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the Setup/Service category menus and items.Unit ConfigurationThe Unit Configuration menu contains parameters that define various basic unit configuration attributes.

AHU ID. AHU ID= is a status only item which identifies the version of application software loaded into the unit main control board (MCB). Refer to “Software Identification and Configuration” on page 129.

CCB1 ID. CCB1 ID= is a status only item which identifies the version of application software loading into the CCB1 auxiliary control board. Refer to “Software Identification and Configuration” on page 129.

CCB2 ID. CCB2 ID= is a status only item which identifies the version of application software loading into the CCB2 auxiliary control board. Refer to “Software Identification and Configuration” on page 129.

GCB1 ID. GCB1 ID= is a status only item which identifies the version of application software loading into the GCB1 auxiliary control board. Refer to “Software Identification and Configuration” on page 129.

EHB1 ID. EHB1 ID= is a status only item which identifies the version of application software loading into the EHB1 auxiliary control board. Refer to “Software Identification and Configuration” on page 129.

ERB1 ID. ERB1 ID= is a status only item which identifies the version of application software loading into the ERB1

Holiday Schedule

Hol 1 N/A-N/A

1 Jan-Dec2 01-313 Jan-Dec4 01-31

Hol 2 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 3 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 4 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 5 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 6 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 7 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 8 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 9 Same As Hol 1 Same As Hol 1 Same As Hol 1

Hol 10 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 11 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 12 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 13 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 14 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 15 Same As Hol 1 Same As Hol 1 Same As Hol 1Hol 16 Same As Hol 1 Same As Hol 1 Same As Hol 1

Optimal Start

Space Temp - - 10 - 95.0 °F

Optimal Start No 1NoYes

Auto Update Yes 1NoYes

Htg Rate 0.4 °F/min 1 0.0 - 1.0 °F/minHtg OAT 35 °F 1 0 - 255 °F

Htg Zero OAT 0 °F 1 -40 - 60 °FClg Rate 0.4 °F/min 1 0.0 - 1.0 °F/minClg OAT 85 °F 1 0 - 255 °F

Clg Zero OAT 100 °F 1 60 - 140 °F

Table 5: Schedules Menus (Continued)


28 OM-137-2

auxiliary control board. Refer to “Software Identification and Configuration” on page 129.

Calibrate Mode. Calibrate Mode= is an adjustable item used to place the unit into the Calib operating state. In this state the unit is shut off and all the unit actuator feedback signals are calibrated. The unit static pressure sensor input signals are also zeroed during this state. For detailed information regarding calibration, refer to “Calibrate Mode” on page 64.

Space Sensor. Space Sensor= is an adjustable item used to indicate whether or not an optional space air temperature sensor is installed. Setting this parameter to “No” disables the alarm function associated with an open circuit at the space temperature sensor input. Also, if “No” is selected, the Cntl Temp Src= parameter cannot be set to “Space” and the Clg Reset= and the Htg Reset= parameters cannot be set to “Space.” For more information regarding the optional space temperature sensor, refer to “Zone (Space) Temperature Sensor” on page 64

EFT Sensor. EFT Sensor= is an adjustable item used to indicate whether or not an optional entering fan air temperature sensor is installed. Setting this parameter to “No” disables the alarm function associated with an open circuit at the EFT temperature sensor input. This sensor is installed only on units equipped with either gas or electric heat and is used by the controller to calculate the heat rise across the heat exchanger by comparing it to the discharge air temperature input. The controller uses this information to protect the heat exchanger against overheating.

2nd P Sensor. 2nd P Sensor= is an adjustable item used to indicate whether or not an optional second static pressure sensor is installed in a unit. When this parameter is set to “Duct”, the controller assumes there is a second duct static pressure sensor installed and displays and controls the unit discharge inlet vanes or VFD based on the lower of the two inputs. When this parameter is set to “Bldg”, the controller assumes there is a second static pressure sensor installed and that it is a building static pressure sensor. In this case the unit return inlet vanes or VFD are controlled to maintain the building pressure at a building pressure set point. When this parameter is set to “None”, the controller assumes there is not a second static pressure sensor installed and ignores the associated analog input. For detailed information regarding discharge and return fan capacity control, refer to “Discharge Fan Capacity Control” on page 108 and “Return Fan Capacity Control” on page 109.

DF CapCtrl. DF CapCtrl= is an adjustable item used to select the type of discharge fan airflow control to be used on a VAV unit. If this parameter is set to “DuctPres”, then the discharge fan airflow is controlled to maintain the duct static pressure at the duct static pressure set point. If this parameter is set to “Position”, then the discharge fan airflow is controlled to an inlet vane position or VFD speed set point set by the Remote DF Cap = parameter. For detailed

information regarding discharge fan capacity control, refer to “Discharge Fan Capacity Control” on page 108.

Remote DF Cap. Remote DF Cap= is an adjustable item which adjusts the discharge air vane position or VFD speed when the DF CapCtrl= parameter is set to “Position.” This parameter can be manually adjusted or set via a network signal. For detailed information regarding discharge fan capacity control, refer to “Discharge Fan Capacity Control” on page 108.

RF/EF Ctrl. RF/EF Ctrl= is an adjustable item used to select the type of return or exhaust fan airflow control to be used. If the unit is equipped with return fan inlets vanes or a VFD and this parameter is set to “Tracking”, then the return fan airflow is controlled based on an adjustable tracking relationship between the discharge fan and return fan airflow. If this parameter is set to “Bldg”, then the return or exhaust fan airflow is controlled independently of the discharge fan airflow to maintain the building static pressure at a building static pressure set point. If this parameter is set to “Position”, then the return or exhaust fan airflow is controlled to an inlet vane position or VFD speed set point set by the Rem RF/EF Cap = parameter. For detailed information regarding return or exhaust fan capacity control, refer to “Return Fan Capacity Control” on page 109 or “Energy Recovery” on page 105.

Rem RF/EF Cap. Rem RF/EF Cap= is an adjustable item which adjusts the return/exhaust air vane position or VFD speed when the RF/EF Ctrl= parameter is set to “Position.” This parameter can be manually adjusted or set via a network signal. It is also used when the Fan Balance= parameter is set to “On” to manually position the return fan vanes or VFD during the fan balance procedure. For detailed information regarding return or exhaust fan capacity control, refer to “Return Fan Capacity Control” on page 109 or “Energy Recovery” on page 105.

Eng Units. Eng Units= is an adjustable item used to select the system of engineering units used for displaying data on the keypad. If this parameter is set to “English”, the keypad data is displayed in inch-pound (I-P) units of measurement. If this parameter is set to “SI Canada”, the keypad data is displayed in the International System of Units (SI) used in Canada. If this parameter is set to “SI Europe”, the keypad data is displayed in the International System of Units (SI) used in Europe.Configuration CodeThe Configuration Code menu contains parameters that indicate the current Software Configuration Code that is programmed into the unit controller. For details regarding the unit Software Configuration Code, refer to “Software Identification and Configuration” on page 129.

Pos # 1-4. Pos # 1-4= is a status only item that displays the first through fourth digits of the Software Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.

OM-137-2 29

Pos # 5-8. Pos # 5-8= is a status only item that displays the fifth through eighth digits of the Software Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.

Pos # 9-12. Pos # 9-12= is a status only item that displays the ninth through twelfth digits of the Software Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.

Pos # 13-16. Pos # 13-16= is a status only item that displays the thirteenth through sixteenth digits of the Software Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.

Pos # 17-20. Pos # 17-20= is a status only item that displays the seventeenth through twentieth digits of the Software Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.

Pos # 21-22. Pos # 21-22= is a status only item that displays the twenty first through twenty second digits of the Software Configuration Code currently loaded into the unit. Note: The decimal point in the display is to be disregarded.PasswordsThe “Passwords” menu contains parameters that relate to the keypad passwords. For detailed information regarding passwords, refer to “Password Protection” on page 10.

Timeout. Timeout= is an adjustable item used to set the duration of a timer which is set whenever the keypad password is entered. Once the password is entered, set points can be changed and alarms can be cleared without reentering the password until this timer expires.

Clear Alarm. Clear Alarm= is an adjustable item used to set which password level is required to allow the user to clear alarms. If this parameter is set to “Lvl 1” then at least the level 1 password must be entered to allow alarms to be cleared. If this parameter is set to “Lvl 2” then the level 2 password must be entered to allow alarms to be cleared. If this parameter is set to “None” then a password entry is not required to allow alarms to be cleared.Operating HoursThe Operating Hours menu contains items that indicate how many hours the fans, cooling and heating, override and energy recover have been operating. This information can be used for scheduling maintenance and monitoring unit operation.

Fan. Fan= is a status item which indicates the hours that the unit fans have operated. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

Mech Cool. Mech Cool= is a status item which indicates the hours that the unit mechanical cooling has operated. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

Comp 1. Comp 1= is a status item which indicates the hours compressor #1 has operated on units equipped with compressorized cooling. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.



Comp 4. Comp 4= is a status item which indicates the hours compressor #4 has operated on units equipped with compressorized cooling. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.Comp 5. Comp 5= is status item which indicates the hours compressor #5 has operated on units equipped with compressorized cooling. This value accumulates to 65,535 before rolling over. This status item can be reset or adjusted manually from the keypad.Comp 6. Comp 6= is status item which indicates the hours compressor #6 has operated on units equipped with compressorized cooling. This value accumulates to 65,535 before rolling over. This status item can be reset or adjusted manually from the keypad.

Heating. Heating= is a status item which indicates the hours that the unit heating has operated. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

Economizer. Economizer= is a status item which indicates the hours that the unit has been in the Econo operating state. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

Tnt Ovrd. Tnt Ovrd= is a status item which indicates the hours that the unit has operated in the schedule tenant override mode of operation. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.

ERecovery. ERecovery= is a status item which indicates the hours that the optional energy recovery system has been in operation. This value accumulates to 65,535 hours before rolling over. This status item can be reset or adjusted manually from the keypad.Timer SettingsThe Timer Settings menu contains several parameters for setting the controller process timers. For detailed

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information regarding these timers, refer to “Control Timer Settings” on page 66.

Service. Service= is an adjustable item which sets a time period during which many of the controller process timers, such as the cooling and heating interstage timers, are sped up. Once this parameter is set to a none-zero time value the fast timers are used until this timer expires.

Recirculate. Recirculate= is an adjustable item which defines the duration of the Recirc operating state.

Low DAT. Low DAT= is an adjustable item which sets the duration of a time period after unit start up during which the Lo Disch Tmp fault is ignored.

Max MWU. Max MWU= is an adjustable item which sets a maximum duration for the MWU (morning warm up) operating state.

Tnt Ovrd. Tnt Ovrd= is an adjustable item which sets the time period during which the unit operates each time the tenant override button on the optional space temperature sensor is pressed or the Occ Mode= parameter is switched to “Tnt Ovrd.” For detailed information regarding tenant override operation refer to “Tenant Override” on page 55.

Start Init. Start Init= is an adjustable item which sets the duration of the Startup operating state.

Post Heat. Post Heat= is an adjustable item which sets the duration of the “post heat” function on VAV units. For detailed information regarding “post heat” operation, refer to “Post Heat Operation” on page 109.Time/DateThe Time/Date menu contains three parameters for setting the controller current date and time. For detailed information regarding these parameters, refer to “Setting Controller Date and Time” on page 56.

Time. Time= is an adjustable item which sets the controller current time.

Note: The time must be entered and is displayed in “mili-tary” time (hh:mm:ss).

Day. Day= is a status only item which displays the current day of the week based on the value of the Date= parameter.

Date. Date= is an adjustable item which sets the current date including date, month and year.Duct Static P SetupThe Duct Static P Setup menu contains several adjustable parameters which affect the response timing for the PID control action used by the controller when modulating the discharge air fan inlet vanes or VFD to maintain duct static pressure on VAV units. For detailed information regarding these control parameters, refer to“MicroTech II DDC Features” on page 126.

DSP Propbd. DSP Propbd= is an adjustable item which sets the “proportional band” used in the PID control function

that modulates the discharge air fan inlet vanes or VFD. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the discharge fan inlet vanes or VFD.

DSP IntTime. DSP IntTime= is an adjustable item which sets the “integral time” used in the PID control function that modulates the discharge air fan inlet vanes or VFD. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the discharge fan inlet vanes or VFD.

DSP Period. DSP Period= is an adjustable item which sets the “sampling period” used in the PID control function that modulates the discharge air fan inlet vanes or VFD. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the discharge fan inlet vanes or VFD.

PRAC. PRAC= is an adjustable item used to automatically tune the duct static pressure control PID parameters. In general this parameter should be left in the “No” setting and should be used only if there are problems with duct static pressure control using the default PID parameters. For detailed information regarding the PRAC function refer to “MicroTech II DDC Features” on page 126.Fan TrackingThe Fan Tracking menu contains parameters that are used to control the return fan airflow capacity on a VAV unit when the RF/EF Ctrl= parameter in the Unit Configuration menu is set to “Tracking.” Fan tracking control maintains building pressurization by varying the return fan air volume as the discharge fan air volume varies. For detailed information regarding return fan tracking, refer to “VaneTrol Fan Tracking Control” on page 109.

DF Max w/oExh. DF Max w/oExh= is an adjustable item which defines the maximum discharge airflow percentage used when the external exhaust fan input indicates that an exhaust fan is not operating (MCB-BI13 off).

RF@DFMax w/oEx. RF@DFMax w/oEx= is an adjustable item which defines the return airflow percentage set point to be used when the discharge fan airflow input is at the DF Max w/oExh= value and when the external exhaust fan input indicates that an exhaust fan is not operating (MCB-BI13 off).

DF Min w/oExh. DF Min w/oExh= is an adjustable item which defines the minimum discharge airflow percentage used when the external exhaust fan input indicates that an exhaust fan is not operating (MCB-BI13 off).

RF@DFMin w/oEx. RF@DFMin w/oEx= is an adjustable item which defines the return airflow percentage set point to be used when the discharge fan airflow input is at the DF Min w/oExh= value and when the external exhaust fan input indicates that an exhaust fan is not operating (MCB-BI13 off).

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DF Max w/Exh. DF Max w/Exh= is an adjustable item which defines the maximum discharge airflow percentage used when the external exhaust fan input indicates exhaust fan operation (MCB-BI13 on).

RF@DFMax w/Ex. RF@DFMax w/Ex= is an adjustable item which defines the return airflow percentage set point used when the discharge fan airflow input is at the DF Max w/Exh= value and when the external exhaust fan input indicates exhaust fan operation (MCB-BI13 on).

DF Min w/Exh. DF Min w/Exh= is an adjustable item which defines the minimum discharge airflow percentage used when the external exhaust fan input indicates exhaust fan operation (MCB-BI13 on).

RF@DFMin w/Ex. RF@DFMin w/Ex= is an adjustable item which defines the return airflow percentage set point used when the discharge fan airflow input is at the DF Min w/Exh= value and when the external exhaust fan input indicates exhaust fan operation (MCB-BI13 on).Fan BalanceThe Fan Balance menu can be used during unit startup to set the proper Fan Tracking menu control parameters. The resultant parameters can be displayed or modified by using the Fan Tracking menu parameters. These parameters apply only when the RF CapCtrl= parameter in the Unit Configuration menu is set to “Tracking.” For detailed information regarding return fan tracking, refer to “VaneTrol Fan Tracking Control” on page 109.

Fan Balance. Fan Balance= is an adjustable item used to turn fan balance operation on and off. When this parameter is set to “On” the unit enters the Balance operating state. In this state, the return air fan inlet vanes or VFD are not controlled based on the discharge fan position but based on the Rem RF/EF Cap= parameter.

Note: This parameter cannot be set to “On” when the unit is in the Off, Startup or Recirc operating states.

Set Max w/o Exh. Set Max w/o Exh= is an adjustable item which is used to set the maximum airflow tracking point used when the external exhaust fan input indicates exhaust fan is not operating (MCB-BI13 off).

Set Min w/o Exh. Set Min w/o Exh= is an adjustable item which is used to set the minimum airflow tracking point used when the external exhaust fan input indicates exhaust fan is not operating (MCB-BI13 off).

Set Max w/ Exh. Set Max w/ Exh= is an adjustable item which is used to set the maximum airflow tracking point used when the external exhaust fan input indicates exhaust fan operation (MCB-BI13 on).

Set Min w/ Exh. Set Min w/ Exh= is an adjustable item which is used to set the minimum airflow tracking point used when the external exhaust fan input indicates exhaust fan operation (MCB-BI13 on).

Rem RF/EF Cap. Rem RF/EF Cap= is an adjustable item which adjusts the return/exhaust air vane position or VFD speed when the RF/EF Ctrl= parameter is set to “Position.” This parameter can be manually adjusted or set via a network signal. It is also used when the Fan Balance= parameter is set to “On” to manually position the return fan vanes of VFD during the fan balance procedure. For detailed information regarding return or exhaust fan capacity control, refer to “Return Fan Capacity Control” on page 109 or “Energy Recovery” on page 105.Bldg Static P SetupThe Bldg Static P Setup menu contains several adjustable parameters which affect the response timing for the PID control action used by the controller when modulating the return or exhaust fan inlet vanes or VFD to maintain building static pressure. These parameters apply only when the RF/EF Ctrl= parameter in the Unit Configuration menu is set to “BldgPres.” For detailed information regarding these control parameters, refer to “MicroTech II DDC Features” on page 126.

BSP Propbd. BSP Propbd= is an adjustable item which sets the “proportional band” used in the PID control function that modulates the return air or exhaust fan inlet vanes or VFD in response to building static pressure. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the return or exhaust fan inlet vanes or VFD.

BSP IntTime. BSP IntTime= is an adjustable item which sets the “integral time” used in the PID control function that modulates the return air or exhaust fan inlet vanes or VFD in response to building static pressure. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the return or exhaust fan inlet vanes or VFD.

BSP Period. BSP Period= is an adjustable item which sets the “sampling period” used in the PID control function that modulates the return air or exhaust fan inlet vanes or VFD. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the return or exhaust fan inlet vanes or VFD.

PRAC. PRAC= is an adjustable item used to automatically tune the building static pressure control PID parameters. In general this parameter should be left in the “No” setting and should be used only if there are problems with building static pressure control using the default PID parameters. For detailed information regarding the PRAC function refer to “MicroTech II DDC Features” on page 126.Exhaust Fan SetupThe Exhaust Fan Setup menu contains several adjustable parameters that affect the control of propeller exhaust fans when a unit is equipped with the propeller exhaust fan option. For detailed information regarding propeller exhaust fan operation, refer to “Propeller Exhaust Fan Control” on page 113.

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Min Exh Fan Cap. Min Exh Fan Cap= is an adjustable item used to determine when the propeller exhaust fans are turned off when a unit is equipped with the propeller exhaust fan option. The exhaust fans are shut off when the building static pressure is below the set point by more than half the dead band and the RF/EF Fan Cap= value has been below this setting for longer than the Min Stop Time= setting. Min OA Dmpr. Min OA Dmpr= is an adjustable item used to set an outdoor damper position minimum value for propeller fan operation when a unit is equipped with the propeller exhaust fan option. The propeller fans will not be turned on unless the outdoor air damper position exceeds this value.Min DF Cap. Min DF Cap= is an adjustable item used on VAV units to set a discharge fan capacity minimum value for propeller fan operation when a unit is equipped with the propeller exhaust fan option. The propeller fans will not be turned on unless the Disch Fan Cap= value exceeds this value (or the unit has a constant volume discharge fan).Min Strt Time. Min Strt Time= is an adjustable item used to set a minimum time period before starting the propeller exhaust fans when a unit is equipped with the propeller exhaust fan option. The propeller fans will not be turned on unless all the conditions required for starting the exhaust fans have been met for at least this time period.Min Stop Time. Min Stop Time= is an adjustable item used to set a minimum time period before stopping the propeller exhaust fans when a unit is equipped with the propeller exhaust fan option. Once started, the propeller fans will not be turned off unless the RF/EF Fan Cap= value has be at or below the Min Exh Fan Cap= setting for longer than this time period.Compressor SetupThe Compressor Setup menu contains several adjustable parameters than affect the compressor and condenser fan staging on units equipped with compressorized cooling. For detailed information regarding compressorized cooling staging operation, refer to “Cooling: Multistage” on page 82.

Lead Circuit. Lead Circuit= is an adjustable item used to select the lead cooling circuit or to select automatic lead/lag of the cooling circuits. For detailed information regarding cooling circuit lead/lag operation, refer to “Compressor Staging” on page 87.

CompCtrl. CompCtrl= is an adjustable item used to select the circuit staging method to be use during cooling operation. When this parameter is set to “Cross Circ”, cooling is staged up and down alternating between cooling circuit #1 and #2. When this parameter is set to “Lead Load”, the “lead” cooling circuit is first staged up completely before the second cooling circuit is staged up. For detailed information regarding circuit staging operation, refer to “Compressor Staging” on page 87.

Clg Method. Clg Method= is an adjustable item used to select the discharge temperature control method to be used

during cooling operation. When this parameter is set to “Average”, cooling is staged up and down to maintain the average discharge temperature over time at the Eff Clg Spt= value in the Discharge Cooling menu. When this parameter is set to “Nearest”, cooling is staged up and down so that a change causes the discharge air temperature to be nearer to the Eff Clg Spt= value than before the change. For detailed information regarding the two discharge air temperature control methods, refer to “Temperature Control” on page 82.

Cond Fan1 Spt. Cond Fan1 Spt= is an adjustable item used to set the outdoor air temperature point above which the first condenser fan in each cooling circuit is turned on.

Cond Fan2 Spt. Cond Fan2 Spt= is an adjustable item used to set the outdoor air temperature point above which the second condenser fan in each cooling circuit is turned on.

Cond Fan3 Spt. Cond Fan3 Spt= is an adjustable item used to set the outdoor air temperature point above which the third condenser fan in each cooling circuit is turned on.

Cond Fan4 Spt. Cond Fan4 Spt= is an adjustable item used to set the outdoor air temperature point above which the fourth condenser fan in each cooling circuit is turned on.

Stage Time. Stage Time= is an adjustable item used to set the minimum time between consecutive cooling staging actions.Chilled Water SetupThe Chilled Water Setup menu contains several adjustable parameters that affect the response timing for the PID control action used by the controller when modulating the chilled water valve to maintain the discharge cooling set point. For detailed information regarding these control parameters, refer to “MicroTech II DDC Features” on page 126.

Clg Propbd. Clg Propbd= is an adjustable item which sets the “proportional band” used in the PID control function that modulates the chilled water valve to maintain the discharge air temperature. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the chilled water valve.

Clg IntTime. Clg IntTime= is an adjustable item which sets the “integral time” used in the PID control function that modulates the chilled water valve to maintain the discharge air temperature. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the chilled water valve.

Clg Period. Clg Period= is an adjustable item which sets the “sampling period” used in the PID control function that modulates the chilled water valve to maintain the discharge air temperature. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the chilled water valve.

PRAC. PRAC= is an adjustable item used to automatically tune the chilled water valve control PID parameters on units

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equipped with chilled water coils. In general this parameter should be left in the “No” setting and should be used only if there are problems with chilled water valve control using the default PID parameters. For detailed information regarding the PRAC function refer to “MicroTech II DDC Features” on page 126.

Stage Time. Stage Time= is an adjustable item used to set a minimum cooling time period. Once a unit enters the Cooling operating state, the chilled water valve must be closed for this time period before the unit leaves the Cooling operating state.Feedback. Feedback= is an adjustable item used to configure the chilled water cooling valve actuator feedback signal on a unit equipped with chilled water cooling. If this item is set to “2 Wire” the controller expects a 0-500Ω resistive signal from the actuator. If this item is set to “3 Wire” the controller expects a 0-5VDC signal from the actuator. Economizer SetupThe Economizer Setup menu contains several adjustable parameters that affect the response timing for the PID control action used by the controller when modulating the economizer dampers to maintain the discharge cooling set point. For detailed information regarding these control parameters, refer to “MicroTech II DDC Features” on page 126.

Clg Propbd. Clg Propbd= is an adjustable item which sets the “proportional band” used in the PID control function that modulates the economizer dampers to maintain the discharge air temperature. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the dampers.

Clg IntTime. Clg IntTime= is an adjustable item which sets the “integral time” used in the PID control function that modulates economizer dampers to maintain the discharge air temperature. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the dampers.

Clg Period. Clg Period= is an adjustable item which sets the “sampling period” used in the PID control function that modulates economizer dampers to maintain the discharge air temperature. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the dampers.

PRAC. PRAC= is an adjustable item used to automatically tune the economizer control PID parameters on units equipped with an economizer. In general this parameter should be left in the “No” setting and should be used only if there are problems with economizer control using the default PID parameters. For detailed information regarding the PRAC function refer to “MicroTech II DDC Features” on page 126.Feedback. Feedback= is an adjustable item used to configure the outdoor air damper actuator feedback signal. If

this item is set to “2 Wire” the controller expects a 0-500Ω resistive signal from the actuator. If this item is set to “3 Wire” the controller expects a 0-5VDC signal from the actuator. DesignFlow SetupThe DesignFlow Setup menu contains several adjustable parameters that affect the response timing for the control action used by the controller when modulating the outdoor air dampers to maintain the MinOA Flow= setting. For detailed information regarding these control parameters, refer to “DesignFlow OA Airflow Measurement Reset” on page 81.

Wait Time. Wait Time= is an adjustable item which sets the “wait time” used in the control function that modulates the Eff Min OA Pos= parameter to maintain the OA Flow= parameter at the MinOA Flow= set point when a unit is equipped with the optional DesignFlow outdoor airflow measuring feature. For details regarding the DesignFlow option, refer to “Minimum Ventilation Control” on page 77.

Modband. Modband= is an adjustable item which sets the “modulation band” used in the control function that modulates the Eff Min OA Pos= parameter to maintain the OA Flow= parameter at the MinOA Flow= set point when a unit is equipped with the optional DesignFlow outdoor airflow measuring feature. For details regarding the DesignFlow option, refer to “Minimum Ventilation Control” on page 79

Wait Time. Wait Time= is an adjustable item which sets the “wait time” used in the control function that modulates the Eff Min OA Pos= parameter to maintain the OA Flow= parameter at the MinOA Flow= set point when a unit is equipped with the optional DesignFlow outdoor airflow measuring feature.

Max Step. Max Step= is an adjustable item which sets the “maximum step” used in the control function that modulates the Eff Min OA Pos= parameter to maintain the OA Flow= parameter at the MinOA Flow= set point when a unit is equipped with the optional DesignFlow outdoor airflow measuring feature.

Deadband. Deadband= is an adjustable item which sets the “deadband” used in the control function that modulates Eff Min OA Pos= parameter to maintain the OA Flow= parameter at the MinOA Flow= set point when a unit is equipped with the optional DesignFlow outdoor airflow measuring feature.

LH Lvl Pos. LH Lvl Pos= is a status item which is used calibrate the left-hand side (unit opposite drive side) of the optional DesignFlow outdoor measuring apparatus. For details regarding calibration of the DesignFlow apparatus, refer to the applicable model-specific installation and maintenance manual (refer to Table 1 on page 4).

RH Lvl Pos. RH Lvl Pos= is a status item which is used calibrate the right-hand side (unit drive side) of the optional

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DesignFlow outdoor measuring apparatus. For details regarding calibration of the DesignFlow apparatus, refer to the applicable model-specific installation and maintenance manual (refer to Table 1 on page 4).AI11 Reference. AI Reference= is an adjustable item used to configure analog input # 11 (AI11) when a unit is equipped with the Design Flow OA airflow measuring option. This item must be set to “No” when the unit is equipped with a “precision” 5 VDC power supply (McQuay PN 111049610) for use with the Design Flow option. In this case, analog input AI11 is not used to determine the current outdoor airflow value. This item must be set to “Yes” on older units which are not equipped with a “precision” 5 VDC power supply (McQuay PN 111049601) for use with the Design Flow option. In this case, analog input AI11 is used to determine the current outdoor airflow value.Heating SetupThe Heating Setup menu contains several adjustable parameters that affect the control action used by the controller to modulate the heating and/or face and bypass damper control actuator to maintain the discharge heating set point.

Stage Time. Stage Time= is an adjustable item used to set a minimum time period between heating staging actions.

F&BP Ctrl. F&BP Ctrl= is an adjustable item used to determine the type of heating valve control to be used on units equipped with face and bypass heating. For detailed information regarding heating face and bypass operation, refer to “Steam or Hot Water Heat: Face and Bypass Damper Control” on page 97.

F&BP Chgovr. F&BP Chgovr= is an adjustable item used to determine when the heating valve is driven fully open when the F&BP Ctrl= parameter is set to “ModValve.” For detailed information regarding heating face and bypass operation, refer to “Steam or Hot Water Heat: Face and Bypass Damper Control” on page 97.

Htg Propbd. Htg Propbd= is an adjustable item which sets the “proportional band” used in the PID control function that modulates the heating valve or face and bypass dampers to maintain the discharge air temperature. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the heating or face and bypass damper control actuator. For detailed information on this PID control parameter, refer to “MicroTech II DDC Features” on page 126.

Htg IntTime. Htg IntTime= is an adjustable item which sets the “integral time” used in the PID control function that modulates the heating valve or face and bypass dampers to maintain the discharge air temperature. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the heating or face and bypass damper control actuator. For detailed information on this PID control parameter, refer to “MicroTech II DDC Features” on page 126.

Htg Period. Htg Period= is an adjustable item which sets the “sampling period” used in the PID control function that modulates the heating valve or face and bypass dampers to maintain the discharge air temperature. In general, increasing this value has a slowing effect and decreasing this value has a speeding effect on the control of the heating or face and bypass damper control actuator. For detailed information on this PID control parameter, refer to “MicroTech II DDC Features” on page 126.

PRAC. PRAC= is an adjustable item used to automatically tune the heating valve control PID parameters on units equipped with an modulating heat. In general this parameter should be left in the “No” setting and should be used only if there are problems with economizer control using the default PID parameters. For detailed information regarding the PRAC function refer to “MicroTech II DDC Features” on page 126.Feedback. Feedback= is an adjustable item used to configure the heating valve actuator feedback signal on a unit equipped with hot water or steam heat. If this item is set to “2 Wire” the controller expects a 0-500Ω resistive signal from the actuator. If this item is set to “3 Wire” the controller expects a 0-5VDC signal from the actuator. Energy Rec SetupThe Energy Rec Setup menu contains several adjustable parameters that affect the control of the energy wheel on units equipped with an energy recovery system. For detailed information regarding these control parameters, refer to “Energy Recovery” on page 105.Min ExhT Diff. Min ExhT Diff= is an adjustable item used to determine when the energy recovery wheel should be slowed down and turned off to protect against wheel frosting when the unit is equipped with the energy recovery wheel frost protection option. Max ExhT Diff. Max ExhT Diff= is an adjustable item used to determine when the energy recovery wheel should be restarted or sped back up after being turned off or slowed down to protect against wheel frosting when the unit is equipped with the energy recovery wheel frost protection option.Stage Time. Stage Time= is an adjustable item used to set a minimum time period between slowing, stopping and increasing the energy recovery wheel speed when a unit is equipped with the energy recovery wheel frost protection option.Min Off Time. Min Off Time= is an adjustable item used to set a minimum time period before restarting the energy recovery wheel when it has been turned off to protect against wheel frosting when a unit is equipped with the energy recovery wheel frost protection option.

Min Exh On. Min Exh On= is an adjustable item used to set a minimum on time for the exhaust fan when a unit is equipped with an optional energy recovery system.

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Min Exh Off. Min Exh Off= is an adjustable item used to set a minimum off time for the exhaust fan when a unit is equipped with an optional energy recovery system. Manual ControlThe Manual Control menu contains parameters used to control the outputs from the controller (MCB) in a manual mode. This can be used to test the operation of the various devices controlled by the outputs. For detailed information regarding manual operation, refer to “Manual Output Control” on page 67.

Manual Control. Manual Control= is an adjustable item used to turn the manual control mode of operation on and off. When this parameter is set to “No” the unit operates normally. When this parameter is set to “Yes” normal control of the control outputs is overridden and the condition of each output is defined by setting the remaining items within the Manual Control menu.

Discharge Fan. Discharge Fan= is an adjustable item used to manually turn the discharge air fan on and off.

RF/EF Fan. RF/EF Fan= is an adjustable item used to manually turn the return air or exhaust fan on and off.

Fan Operation. Fan Operation= is an adjustable item used to manually turn the Fan Operation Output (MCB-BO3) on and off.

Alarm. Alarm= is an adjustable item used to manually turn the Remote Alarm Output (MCB-BO4) on and off.

OA Damper. OA Damper= is an adjustable item used to manually drive the outdoor air dampers open and closed.

Mod Cooling. Mod Cooling= is an adjustable item used to manually drive the modulating cooling valve open and closed.

Mod Heating. Mod Heating= is an adjustable item used to manually drive the modulating heating valve open and closed.

VAV Output. VAV Output= is an adjustable item used to manually turn the VAV Box Output (MCB-BO12) on and off.

Disch Vanes. Disch Vanes= is an adjustable item used to manually drive the discharge air fan inlet vanes open and closed.

RF/EF Vanes. RF/EF Vanes= is an adjustable item used to manually drive the return air or exhaust fan inlet vanes open and closed.

Disch VFD. Disch VFD= is an adjustable item used to manually increase and decrease the discharge air fan VFD speed.

RF/EF VFD. RF/EF VFD= is an adjustable item used to manually increase and decrease the return air or exhaust fan VFD speed.

Alarm Out FaultsThe Alarm Out Faults menu contains parameters for determining the action of the Remote Alarm Output (MCB-BO4) when “fault” alarms occur. The Remote Alarm Output is on continuously when there are no active alarms within the controller. Each alarm can be set up to cause the Remote Alarm Output to turn off, blink quickly, blink slowly or remain on continuously when the alarm occurs. For detailed information on configuring the Remote Alarm Output, refer to “Configuring Remote Alarm Output.” on page 63.

Freeze. Freeze= is an adjustable item used to determine the action of the Remote Alarm Output when the Freeze fault occurs.

Smoke. Smoke= is an adjustable item used to determine the action of the Remote Alarm Output when the Smoke fault occurs.

OAT Sensor. OAT Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the OAT Sensor fault occurs.

Space Sensor. Space Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the Space Sensor fault occurs.

Return Sensor. Return Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the Return Sensor fault occurs.

Disch Sensor. Disch Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the Disch Sensor fault occurs.

Duct Hi Limit. Duct Hi Limit= is an adjustable item used to determine the action of the Remote Alarm Output when the Duct Hi Limit fault occurs.

Hi Return Tmp. Hi Return Tmp= is an adjustable item used to determine the action of the Remote Alarm Output when the Hi Return Tmp fault occurs.9

Hi Disch Tmp. Hi Disch Tmp= is an adjustable item used to determine the action of the Remote Alarm Output when the Hi Disch Tmp fault occurs.

Lo Disch Tmp. Lo Disch Tmp= is an adjustable item used to determine the action of the Remote Alarm Output when the Lo Disch Tmp fault occurs.

Fan Fail. Fan Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the Fan Fail fault occurs.

OA Dmpr Stuck. OA Dmpr Stuck= is an adjustable item used to determine the action of the Remote Alarm Output when the OA Dmpr Stuck fault occursAlarm Out ProblemsThe Alarm Out Problems menu contains parameters for determining the action of the Remote Alarm Output (MCB-BO4) when “problem” alarms occur. The Remote Alarm Output is on continuously when there are no active alarms

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within the controller. Each alarm can be set up to cause the Remote Alarm Output to turn off, blink quickly, blink slowly or remain on continuously when the alarm occurs. For detailed information regarding configuring the Remote Alarm Output, refer to “Configuring Remote Alarm Output.” on page 63.

Freeze. Freeze= is an adjustable item used to determine the action of the Remote Alarm Output when the Freeze problem occurs.

OAT Sensor. OAT Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the OAT Sensor problem occurs.

Space Sensor. Space Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the Space Sensor problem occurs.

Return Sensor. Return Sensor= is an adjustable item used to determine the action of the Remote Alarm Output when the Return Sensor problem occurs.

Ent Fan Sens. Ent Fan Sens= is an adjustable item used to determine the action of the Remote Alarm Output when the Ent Fan Sens problem occurs.

Lo Airflow. Lo Aiflow= is an adjustable item used to determine the action of the Remote Alarm Output when the Lo Airflow problem occurs.

Heat Fail. Heat Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the Heat Fail problem occurs.

Fan Retry. Fan Retry= is an adjustable item used to determine the action of the Remote Alarm Output when the Fan Retry problem occurs.

Hi Pres-Ckt1. Hi Pres-Ckt1= is an adjustable item used to determine the action of the Remote Alarm Output when the Hi Pres-Ckt1 problem occurs.

Hi Pres-Ckt2. Hi Pres-Ckt2= is an adjustable item used to determine the action of the Remote Alarm Output when the Hi Pres-Ckt2 problem occurs.

Lo Pres-Ckt1. Lo Pres-Ckt1= is an adjustable item used to determine the action of the Remote Alarm Output when the Lo Pres-Ckt1 problem occurs.

Lo Pres-Ckt2. Lo Pres-Ckt2= is an adjustable item used to determine the action of the Remote Alarm Output when the Lo Pres-Ckt2 problem occurs.

Frost-Ckt1. Frost-Ckt1= is an adjustable item used to determine the action of the Remote Alarm Output when the Frost-Ckt1 problem occurs.

Frost-Ckt2. Frost-Ckt2= is an adjustable item used to determine the action of the Remote Alarm Output when the Frost-Ckt2 problem occurs.

Comp #1 Alm. Comp #1 Alm= is an adjustable item used to determine the action of the Remote Alarm Output when the Comp #1 Alm problem occurs.



Comp #4 Alm. Comp #4 Alm= is an adjustable item used to determine the action of the Remote Alarm Output when the Comp #4 Alm problem occurs.Comp #5 Alm. Comp #5 Alm= is an adjustable item used to determine the action of the Remote Alarm Output when the Comp #5 Alm problem occurs.Comp #6 Alm. Comp #6 Alm= is an adjustable item used to determine the action of the Remote Alarm Output when the Comp #6 Alm problem occurs.

PumpDown-Ckt1. PumpDown-Ckt1= is an adjustable item used to determine the action of the Remote Alarm Output when the PumpDown-Ckt1 problem occurs.

PumpDown-Ckt2. PumpDown-Ckt2= is an adjustable item used to determine the action of the Remote Alarm Output when the PumpDown-Ckt2 problem occurs.

Ckt1 Clg Ena. Ckt1 Clg Ena= is an adjustable item used to determine the action of the Remote Alarm Output when the Ckt1 Clg Ena problem occurs.

Ckt2 Clg Ena. Ckt2 Clg Ena= is an adjustable item used to determine the action of the Remote Alarm Output when the Ckt2 Clg Ena problem occurs.

GenC Clg Ena. GenC Clg Ena= is an adjustable item used to determine the action of the Remote Alarm Output when the GenC Clg Ena problem occurs.

HtgB Htg Ena. HtgB Htg Ena= is an adjustable item used to determine the action of the Remote Alarm Output when the HtgB Htg Ena problem occurs.

Ckt1 Comm Fail. Ckt1 Comm Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the Ckt1 Comm Fail problem occurs.

Ckt2 Comm Fail. Ckt2 Comm Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the Ckt2 Comm Fail problem occurs.

GenC Comm Fail. GenC Comm Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the GenC Comm Fail problem occurs.

HtgB Comm Fail. HtgB Comm Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the HtgB Comm Fail problem occurs.

OM-137-2 37

ERecB Comm Fail. ERecB Comm Fail= is an adjustable item used to determine the action of the Remote Alarm Output when the ERecB Comm Fail problem occurs.Alarm Out WarningsThe Alarm Out Warnings menu contains parameters for determining the action of the Remote Alarm Output (MCB-BO4) when “warning” alarms occur. The Remote Alarm Output is on continuously when there are no active alarms within the controller. Each alarm can be set up to cause the Remote Alarm Output to turn off, blink quickly, blink slowly or remain on continuously when the alarm occurs. For detailed information regarding configuring the Remote Alarm Output, refer to “Configuring Remote Alarm Output.” on page 63.

Airflow Switch. Airflow Switch= is an adjustable item used to determine the action of the Remote Alarm Output when the Airflow Switch warning occurs.

Dirty Filter. Dirty Filter= is an adjustable item used to determine the action of the Remote Alarm Output when the Dirty Filter warning occurs.

Dirty FnlFltr. Dirty FnlFltr= is an adjustable item used to determine the action of the Remote Alarm Output when the Dirty FnlFltr warning occurs.

Ckt1 H/W. Ckt1 H/W= is an adjustable item used to determine the action of the Remote Alarm Output when the Ckt1 H/W warning occurs.

Ckt2 H/W. Ckt2 H/W= is an adjustable item used to determine the action of the Remote Alarm Output when the Ckt2 H/W warning occurs.

GenC H/W. GenC H/W= is an adjustable item used to determine the action of the Remote Alarm Output when the GenC H/W warning occurs.

HtgB H/W. HtgB H/W= is an adjustable item used to determine the action of the Remote Alarm Output when the HtgB H/W warning occurs.Alarm LimitsThe Alarm Limits menu contains parameters for setting three miscellaneous temperature alarm limits.

Hi Disch Alm. Hi Disch Alm= is an adjustable item which sets a high discharge air temperature alarm limit. If the discharge air temperature input exceeds this setting, the unit shuts down completely on the Hi Disch Tmp fault.

Lo Disch Alm. Lo Disch Alm= is an adjustable item which sets a low discharge air temperature alarm limit. If the discharge air temperature input falls below this setting while mechanical cooling is not operating, the unit shuts down completely on the Lo Disch Tmp fault.

Hi Return Alm. Hi Return Alm= is an adjustable item which sets a high return air temperature alarm limit. If the return air temperature input exceeds this setting, the unit shuts down completely on the Hi Return Tmp fault.

38 OM-137-2

Table 6: Setup/Services Menus


Unit Configuration

AHU ID - - xxxxxxxxxxCCB1 ID - - xxxxCCB2 ID - - xxxxGCB1 ID - - xxxxEHB1 ID - - xxxxERB1 ID - - xxxx

Calibrate Mode No 1NoYes

Space Sensor Yes 1NoYes

EFT Sensor No 1NoYes

2nd P Sensor None 1NoneDuctBldg

DF CapCtrl DuctPres 1DuctPresPosition

Remote DF Cap 25% 1 0-100%

RF/EF Ctrl Tracking 1

NoneTrackingBldgPresPosition

Rem RF/EF Cap 25% 1 0-100%

Eng Units EnglishEnglish

SI CanadaSI Europe

Configuration Code

Pos # 1-4 - - 0.000-3.388Pos # 5-8 - - 0.000-1.934

Pos # 9-12 - - 0.000-7.810Pos # 13-16 - - 0.000-9.243Pos # 17-20 - - 0.000-2.121Pos # 21-22 - - 0.0-2.1

Passwords

Timeout 15 min 1 2-60 min

Clear Alarm None 1NoneLvl-1Lvl-2

Operating Hours

Fan 0 1 0-65535 hr.Mech Cool 0 1 0-65535 hr.

Comp 1 0 1 0-65535 hr.Comp 2 0 1 0-65535 hr.Comp 3 0 1 0-65535 hr.Comp 4 0 1 0-65535 hr.Comp 5 0 1 0-65535 hr.Comp 6 0 1 0-65535 hr.Heating 0 1 0-65535 hr.

Economizer 0 1 0-65535 hr.Tnt Ovrd 0 1 0-65535 hr.

ERecovery 0 1 0-65535 hr.

* Varies according to model. Refer to Table 40 on page 90 and Table 41 on

OM-137-2 39

page 91.

Timer Settings

Service 0 min 1 0 - 240 minRecirculate 3 min 1 2 - 60 minLow DAT 3 min 1 2 - 60 min

Max MWU 90 min 1 0 - 240 minTnt Ovrd 120 min 1 0 - 300 minStart Init 180 sec 1 0 - 240 sec

Post Heat 0 min 1 0-3 min

Time/Date

Timehh 1 00 - 23

mm 2 00 -59ss 3 00 - 59

Day - - Mon - Sun

Datedt 1 01-31

mon 2 Jan - Decyear 3 1999-2155

Duct Static P Setup

DSP Propbd 6.0 “WC 1 0.1-30.0 “WCDSP IntTime 12 sec 1 0-3600 secDSP Period 10 sec 1 2-30 sec

PRAC No 1NoYes

Fan Tracking

DF Max w/oExh 100% 1 0 - 100%RF@DFMax w/oEx 95% 1 0 - 100%

DF Min w/oExh 20% 1 0 - 100%RF@DFMin w/oEx 15% 1 0 - 100%

DF Max w/Exh 100% 1 0 - 100%RF@DFMax w/Ex 60% 1 0 - 100%

DF Min w/ Exh 20% 1 0 - 100%RF@DFMin w/Exh 10% 1 0 - 100%

Fan Balance

Fan Balance Off 1OffOn

Set Max w/o Exh No 1NoYes

Set Min w/o Exh No 1NoYes

Set Max w/ Exh No 1NoYes

Set Min w/ Exh No 1NoYes

Rem RF/EF Cap 25% 1 0-100%

Bldg Static P Setup

BSP Propbd 1.0 “WC 1 0.1-30.0 “WCBSP IntTime 10 sec 1 0-3600 sec

PRAC No 1NoYes

Exhaust Fan Setup

Min OA Dmpr Pos 5% 1 1 - 99%Min DF Cap 10% 1 1 - 99%Min Strt Time 120 sec 1 10 - 240 secMin Stop Time 120 sec 1 10 - 240 sec

Table 6: Setup/Services Menus (Continued)


40 OM-137-2

Compressor Setup

Lead Circuit #1 1Auto#1#2

CompCtrl Cross Circ 1Cross CircLead Load

Clg Method Average 1AverageNearest

Cond Fan1 Spt 0 °F 1 0-105 °FCond Fan2 Spt 55 °F * 1 0-105 °FCond Fan3 Spt 65 °F * 1 0-105 °FCond Fan4 Spt 75 °F * 1 0-105 °FCond Fan Diff 5 °F 1 5-20 °F

Stage Time 5 min 1 5-60 min

Chilled Water Setup

Clg Propbd 30 °F 1 1-100 °FClg IntTime 60 sec 1 0-3600 secClg Period 30 sec 1 1-3600 sec

PRAC No 1NoYes


Feedback 3 Wire 13 Wire2 Wire

Economizer Setup

Clg Propbd 30 °F 1 1-100 °FClg IntTime 60 sec 1 0-3600 secClg Period 30 sec 1 1-3600 sec

PRAC No 1NoYes


DesignFlow Setup

Wait Time 30 sec 1 0-180 secModband 50% 1 10-100%Max Step 5.0% 1 0.1-9.9%

DeadBand 6.00% 1 0.01-9.99%LH Lvl Pos - 1 0-100%RH Lvl Pos - 1 0-100%

AI II Reference No 1NoYes

Heating Setup


F&BP Ctrl OpenValve 1OpenValveMod Valve

F&BP Chgovr 37 °F 1 0-60 °FHtg Propbd 20 °F 1 1-100 °FHtg IntTime 120 sec 1 0-3600 secHtg Period 60 sec 1 1-3600 sec

PRAC No 1NoYes




OM-137-2 41

Energy Rec Setup

Min Exh T 2°F 1 1-10°FMin Exh T 6°F 1 1-20°FStage Time 5 Min 1 1-100 min

Min Off Time 20 Min 1 1-100 minMin Exh On 120 Sec 1 60-300 secMin Exh Off 120 Sec 1 60-300 sec

Manual Control

Manual Control No 1NoYes

Discharge Fan Off 1OnOff

RF/EF Fan Off 1OnOff

Fan Operation Off 1OnOff

Alarm Normal 1Alarm

Normal

OA Damper Auto 1CloseAutoOpen

Mod Cooling Auto 1CloseAutoOpen

Mod Heating Auto 1CloseAutoOpen

VAV Output Heat 1HeatCool

Disch Vanes Auto 1CloseAutoOpen

RF/EF Vanes Auto 1CloseAutoOpen

Disch VFD Auto 1SlowerAuto

Faster

RF/EF VFD Auto 1SlowerAuto

Faster



42 OM-137-2

Alarm Out Faults

Freeze Fast 1

OnOff

FastSlow

Smoke Fast 1 Same As FreezeOAT Sensor Fast 1 Same As Freeze

Space Sensor Fast 1 Same As FreezeReturn Sensor Fast 1 Same As FreezeDisch Sensor Fast 1 Same As FreezeDuct Hi Limit Fast 1 Same As Freeze

Hi Return Tmp Fast 1 Same As FreezeHi Disch Tmp Fast 1 Same As FreezeLo Disch Tmp Fast 1 Same As Freeze

Fan Fail Fast 1 Same As FreezeOA Dmpr Stuck Fast 1 Same As Freeze

Alarm Out Problems

Freeze Slow 1

OnOff

FastSlow

OAT Sensor Slow 1 Same As FreezeSpace Sensor Slow 1 Same As FreezeReturn Sensor Slow 1 Same As FreezeEnt Fan Sens Slow 1 Same As Freeze

Lo Airflow Slow 1 Same As FreezeHeat Fail Slow 1 Same As FreezeFan Retry Slow 1 Same As Freeze

Hi Pres-Ckt1 Slow 1 Same As FreezeHi Pres-Ckt2 Slow 1 Same As FreezeLo Pres-Ckt1 Slow 1 Same As FreezeLo Pres-Ckt2 Slow 1 Same As Freeze

Frost-Ckt1 Slow 1 Same As FreezeFrost-Ckt2 Slow 1 Same As Freeze

Comp #1 Alm Slow 1 Same As FreezeComp #2 Alm Slow 1 Same As FreezeComp #3 Alm Slow 1 Same As FreezeComp #4 Alm Slow 1 Same As FreezeComp #5 Alm Slow 1 Same As FreezeComp #6 Alm Slow 1 Same As Freeze

PumpDown-Ckt1 Slow 1 Same As FreezePumpDown-Ckt2 Slow 1 Same As Freeze

Ckt1 Clg Ena Slow 1 Same As FreezeCkt2 Clg Ena Slow 1 Same As Freeze

GenC Clg Ena Slow 1 Same As FreezeHtgB Htg Ena Slow 1 Same As Freeze

Ckt1 CommFail Slow 1 Same As FreezeCkt2 CommFail Slow 1 Same As Freeze

GenC CommFail Slow 1 Same As FreezeHtgB CommFail Slow 1 Same As Freeze

ERecB CommFail Slow 1 Same As Freeze



OM-137-2 43

Alarm Out Warnings

Airflow Switch Off 1

OnOff

FastSlow

Dirty Filter Off 1 Same As OA Dmpr StuckDirty FnlFltr Off 1 Same As OA Dmpr StuckCkt1 H/W Off 1 Same As OA Dmpr StuckCkt2 H/W Off 1 Same As OA Dmpr Stuck

GenC H/W Off 1 Same As OA Dmpr StuckHtgB H/W Off 1 Same As OA Dmpr Stuck

Alarm LimitsHi Discharge Alm 170 °F 1 90 - 250 °FLo Discharge Alm 40 °F 1 20 - 50 °F

Hi Return Alm 120 °F 1 90 - 150 °F



44 OM-137-2

Active AlarmsMenus in the Active Alarms category contain alarm information for up to 4 active alarms. Table 7 on page 46 lists all menus and items in the Active Alarms group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the Active Alarms category menus and items. For detailed information regarding alarm handling, refer to “Alarm Monitoring” on page 59 and “Alarm Control” on page 115.Active Alarm 1The Active Alarm 1 menu provides details regarding the highest priority active alarm.

Alarm Name. Alarm Name= is a status only item that identifies the name of Active Alarm 1.

Alarm Type. Alarm Type= is a status only item that identifies the alarm type (fault, problem or warning) of Active Alarm 1.

Alarm Date and Time. This is a status only item that indicates the date and time of occurrence of Active Alarm 1.Active Alarm 2The Active Alarm 2 menu provides details regarding the second highest priority active alarm.



Alarm Date and Time. This is a status only item that indicates the date and time of occurrence of Active Alarm 2.Active Alarm 3The Active Alarm 3 menu provides details regarding the third highest priority active alarm.



Alarm Date and Time. This is a status only item that indicates the date and time of occurrence of Active Alarm 3.Active Alarm 4The Active Alarm 4 menu provides details regarding the fourth highest priority active alarm.



Alarm Date and Time. This is a status only item that indicates the date and time of occurrence of Active Alarm 4.

OM-137-2 45

Table 7: Active Alarm Menus


Active Alarm 1

Alarm Name - -

NoneFreeze (Fault)Smoke (Fault)

OAT Sensor (Fault)Space Sensor (Fault)Return Sensor (Fault)Disch Sensor (Fault)Duct Hi Limit (Fault)

Hi Return Tmp (Fault)Hi Disch Tmp (Fault)Lo Disch Tmp (Fault)

Fan Fail (Fault)OA Dmpr Stuck (Fault)

Freeze (Problem)OAT Sensor (Problem)

Space Sensor (Problem)Return Sensor (Problem)Ent Fan Sens (Problem)

Lo Airflow (Problem)Heat Fail (Problem)Fan Retry (Problem)

Hi Pres-Ckt1 (Problem)Hi Pres-Ckt2 (Problem)Lo Pres-Ckt1 (Problem)Lo Pres-Ckt2 (Problem)

Frost-Ckt1 (Problem)Frost-Ckt2 (Problem)

Comp #1 Alm (Problem)Comp #2 Alm (Problem)Comp #3 Alm (Problem)Comp #4 Alm (Problem)Comp #5 Alm (Problem)Comp #6 Alm (Problem)

PumpDown-Ckt1 (Problem) PumpDown-Ckt2 (Problem)

Ckt1 Clg Ena (Problem)Ckt2 Clg Ena (Problem)

GenC Clg Ena (Problem)HtgB Htg Ena (Problem)

Ckt1 Comm Fail (Problem)Ckt2 Comm Fail (Problem)

GenC Comm Fail (Problem)HtgB Comm Fail (Problem)

ERecB Comm Fail (Problem)Airflow Switch (Warning)

Dirty Filter (Warning)Drty FnlFltr (Warning)Ckt1 H/W (Warning)Ckt2 H/W (Warning)

GenC H/W (Warning)HtgB H/W (Warning)

Alarm Type - -

-Fault-Active

Problem-ActiveWarning-Active

Alarm Date and Time - - dd-mmm-yy/hh:mm:ss

46 OM-137-2

Active Alarm 2

Alarm Name Same As Active Alm 1

Alarm Type - -

-Fault-Active

Problem- ActiveWarning- Active

Alarm Date and Time dd-mmm-yy/hh:mm:ss

Active Alarm 3


Alarm Type - -

-Fault- Active


Alarm Date and Time dd-mmm-yy/hh:mm:ss

Active Alarm 4


Alarm Type - -

-Fault- Active



Table 7: Active Alarm Menus (Continued)


OM-137-2 47

Previous AlarmsMenus in the Previous Alarms category contain alarm information for up to 8 previous alarms. Table 8 lists all menus and items in the Previous Alarms group or category. The “Range” column in the table lists all possible values for each item. The factory settings for the adjustable parameters are shown in the “Factory Default Value” column. The following are brief descriptions of the Previous Alarms category menus and items. For detailed information regarding alarm handling, refer to “Alarm Monitoring” on page 59 and “Alarm Control” on page 115.Previous Alarm 1The Previous Alarm 1 menu provides details regarding the most recently cleared previous alarm.

Alarm Name. Alarm Name= is a status only item that identifies the name of Previous Alarm 1.

Alarm Type. Alarm Type= is a status only item that identifies the alarm type (fault, problem or warning) of Previous Alarm 1.

Alarm Date and Time. This is a status only item that indicates the date and time of occurrence of Previous Alarm 1.Previous Alarm 2 through Previous Alarm 8The Previous Alarm 2 through the Previous Alarm 8 menus provide details regarding the second through eighth most recently cleared previous alarm. The description of these menus is identical to Previous Alarm 1.

Table 8: Previous Alarm Menus


Previous Alarm 1

Alarm Name - - Same As Active Alm 1

Alarm Type - -

-

Fault- Clear

Problem- Clear

Warning- Clear

Alarm Date and Time - dd-mmm-yy/hh:mm:ss

Previous Alarm 2


Alarm Type - - Same As Previous Alm 1


Previous Alarm 3




Previous Alarm 4




Previous Alarm 5




Previous Alarm 6




Previous Alarm 7




Previous Alarm 8




48 OM-137-2

Remote Keypad Display OptionNote: A unit may be equipped with a remote keypad/dis-

play option. When this is the case either the local unit keypad/display or the remote keypad/display is active. When the selector switch on the remote key-pad/display control board in the unit is switched to the “local” setting, the local keypad/display is active and the remote keypad/display is disabled (the “local” LED on the board is ON and the “remote” LED on the board is OFF). When the selector switch is switched to the “remote” setting, the remote keypad/display is active and the local keypad/display is disabled (the “local” LED on the board is OFF and the “remote” LED on the board is ON). Note: When the selector switch position is changed, the selected keypad/display goes through the “normal” power up sequence before becoming active. This generally takes about 60 seconds.

The operation of the remote keypad is identical to that of the local keypad/display as described in the previous sections.

CAUTIONUnit can be started from a remote location. Injury to others can occur.

When the remote keypad is enabled, the potential exits for the unit to be started from a remote loca-tion. Make sure the keypad/display selector switch is in the "local" position ("local" LED on the remote keypad/display control board is ON and the "remote" LED is OFF) or that remote keypad is physically disconnected before servicing the unit. If the local unit keypad/display is blank, it is most likely that the remote keypad display is active.

OM-137-2 49

Operator’s GuideThe following “Operator’s Guide” sections provide information regarding the day-to-day operation of the MicroTech II Applied Rooftop Unit Controller. Topics covered are such common tasks as scheduling, displaying and clearing alarms, and setting the controller for manual operation. Programmable parameters that affect the operation being described are listed at the beginning of each applicable sub-section. The factory default values for these parameters are shown in italic letters.For detailed information regarding the control processes and their programmable parameters, refer to “Description of Operation” on page 70.

Determining Unit StatusThe System menu includes several parameters that can be used to determine the overall status of the unit. There are five key items in this menu that summarize the current operating condition of the unit. These are: UnitStatus=, Clg Capacity=, Htg Capacity=, Clg Status=, and Htg Status= and are described in the following sections.

Unit StatusThe UnitStatus= parameter in the System menu is very useful because the item summarizes the overall operating condition of the unit. Each of the possible conditions is referred to as an “operating state”. The following are the possible operating states displayed by the UnitStatus= parameter.

• Off• Calib• Startup • Recirc• Fan Only• Econo• Cooling• MWU• Heating• Min DAT• UnocEcon• UnocClg• UnocHtg• Balance• Man Ctrl

The unit makes transitions between these operating states as conditions change. For detailed information regarding these states, refer to “Operating States and Sequences” on page 70.

Clg CapacityClg Capacity= is a status item which indicates the percentage of the unit maximum cooling capacity currently

operating. When the unit is equipped with chilled water cooling, 0-100% is displayed as the cooling valve actuator strokes from the closed to open position. When the unit is equipped with compressorized cooling, the percentage value changes incrementally based on the number operating cooling stages.

Htg CapacityHtg Capacity= is a status item which indicates the percentage of the unit maximum heating capacity currently operating. When the unit is equipped with modulating heat, 0-100% is displayed as the heating valve actuator strokes from the closed to open position. When the unit is equipped with staged heat, the percentage value changes incrementally based on the number operating heating stages

Clg StatusClg Status= is a status item which indicates whether or not cooling (economizer and/or mechanical) is currently allowed. If cooling is disabled, the reason is indicated. The following are descriptions of the various “Clg Status” states.All ClgThe Clg Status= parameter indicates “All Clg” when both of the following conditions are true:1. The unit is equipped with an economizer and the out-

door air is suitable for free cooling (OA Ambient= parameter in the OA Damper menu indicates “Low”).

2. The outdoor air is warm enough to allow mechanical cooling operation (OA Temp= parameter in the Temper-atures menu has risen above the OATComp Lock= parameter by more that the OATLock Diff= setting in the Zone Cooling menu).

In this state the unit uses the economizer, mechanical cooling or both as required to maintain the cooling set points.EconoThe Clg Status= parameter indicates “Econo” when both of the following conditions are true:1. The unit is equipped with an economizer and the out-

door air is suitable for free cooling (OA Ambient= parameter in the OA Damper menu indicates “Low”).

2. The outdoor air is too cool to allow mechanical cooling operation (OA Temp= parameter in the Temperatures menu has dropped below the OATComp Lock= setting in the Zone Cooling menu).

In this state the unit only uses the economizer to maintain the cooling set points. Mechanical cooling operation is disabled.Mech ClgThe Clg Status= parameter indicates “Mech Clg” when both of the following conditions are true:

50 OM-137-2

1. The unit is not equipped with an economizer or the out-door air is not suitable for free cooling (OA Ambient= parameter in the OA Damper menu indicates “High”).

2. The outdoor air is warm enough to allow mechanical cooling operation (OA Temp= parameter in the Temper-atures menu has risen above the OATComp Lock= parameter by more that the OATLock Diff= setting in the Zone Cooling menu).

In this state the unit only uses mechanical cooling to maintain the cooling set points. Economizer operation is disabled, and the outdoor air damper is maintained at the Eff Min OA Pos= value.Off AmbThe Clg Status= parameter indicates “Off Amb” when both of the following conditions are true:1. The unit is not equipped with an economizer or outdoor

air is not suitable for free cooling (OA Ambient= param-eter in the OA Damper menu indicates “High”).

2. The outdoor air is too cool to allow mechanical cooling operation (OA Temp= in the Temperatures menu has dropped below the OATComp Lock= setting in the Zone Cooling menu).

In this state both economizer and mechanical cooling operation is disabled.For applications that use an economizer, the “Off Amb” state should not occur if the economizer changeover and mechanical cooling lockout set points are adjusted properly. If it does occur, it may indicate a problem with the enthalpy sensing device.Off AlmThe Clg Status= parameter indicates “Off Alm” when cooling related alarms cause all cooling circuits to be completely disabled and economizer operation is not available. For detailed information regarding cooling alarms and their effect on the unit operation, Refer to “Alarm Control” on page 115. All cooling is disabled during the “Off Alm” state.Off SwThe Clg Status= parameter indicates “Off Sw” when the field cooling enable terminals 101 to 105 on terminal block TB2 in the main control panel are not made (binary input MCB-BI3 is off). Refer to the “Manual Cooling and Heating Enable/Disable” section of IM 696, MicroTech Applied Rooftop Unit Controller. All cooling is disabled during the “Off Sw” state.Off ManThe Clg Status= parameter indicates “Off Man” when cooling is disabled via the Ctrl Mode= parameter in the System menu. This occurs when the Ctrl Mode= parameter is set to either “Heat Only” or “Fan Only.” All cooling is disabled during the “Off Man” state.

Off NetThe Clg Status= parameter indicates “Off Net” when cooling is disabled by a network signal affecting the Appl Mode= parameter in the System menu. This is the case when the Appl Mode= parameter is set to either “Heat Only” or “Fan Only.” All cooling is disabled during the “Off Net” state.Off NoneThe Clg Status= parameter indicates “Off None” when the unit is equipped with no cooling of any kind.

Htg StatusHtg Status= is a status item which indicates whether or not heating is currently allowed. If heating is disabled, the reason is indicated. The following are descriptions of the various “Htg Status” states.Htg EnaThe Htg Status= parameter indicates “Htg Ena” when the unit is equipped with some kind of heating and the outdoor air is cool enough to allow heating operation and heat is not disabled for some other reason. (OA Temp= parameter in the Temperatures menu has dropped below the OATHtg Lock= parameter by more that the OATLock Diff= setting in the Zone Heating menu). In this state the unit uses the heat as required to maintain the heating set points.Off AmbThe Htg Status= parameter indicates “Off Amb” when the unit is equipped with heat and the outdoor air is too warm to allow heating operation (OA Temp= parameter in the Temperatures menu has risen above the OATHtg Lock= setting in the Zone Heating menu). In this state heating operation is disabled.Off AlmThe Htg Status= parameter indicates “Off Alm” when heating related alarms cause all heating to be completely disabled. For detailed information regarding heating alarms and their effect on the unit operation, refer to “Alarm Control” on page 115. All heating is disabled during the “Off Alm” state.Off SwThe Htg Status= parameter indicates “Off Sw” when the field heating enable terminals 101 to 106 on terminal block TB2 in the main control panel are not made (binary input MCB-BI4 off). Refer to the “Manual Cooling and Heating Enable/Disable” section of IM 696, MicroTech Applied Rooftop Unit Controller. Heating is disabled during the “Off Sw” state.Off ManThe Htg Status= parameter indicates “Off Man” when heating is disabled via the Ctrl Mode= parameter in the System menu. This occurs when the Ctrl Mode= parameter is set to either “Cool Only” or “Fan Only.” Heating is disabled during the “Off Man” state.

OM-137-2 51

Off NetThe Htg Status= parameter indicates “Off Net” when heating is disabled by a network signal affecting the Appl Mode= parameter in the System menu. This occurs when the Appl Mode= parameter is set to either “Cool Only” or “Fan Only.” Heating is disabled during the “Off Net” state.Off NoneThe Htg Status= parameter indicates “Off None” when the unit is equipped with no heating.

Auto/Manual OperationThe System menus includes two parameters that determine whether cooling, heating, both cooling and heating or neither are enabled during unit operation. These are the Ctrl Mode= and Appl Mode= parameters. The Occupancy menu includes five parameters that relate to the occupied/unoccupied condition (start/stop) of the unit. These are the Occupancy=, Occ Mode=, Occ Src=, Bypass Time=, and Emerg Override= parameters. These are described in the following sections.

Ctrl Mode

The unit cooling and heating can be set up for automatic heat/cool, cool only, heat only, fan only, or network cool/heat operation by setting the Control Mode. The unit can also be manually disabled via the Control Mode. The following are descriptions of the six available Control Mode selections.OffWhen the Control Mode is set to “Off”, the UnitStatus= is “Off Man” and the unit is completely disabled.Heat CoolWhen the Control Mode is set to “Heat/Cool”, both cooling and heating operation are allowed to operate as required to maintain the cooling and heating set points.Cool OnlyWhen the Control Mode is set to “Cool Only”, cooling operation is allowed to operate to maintain the cooling set points. Heating operation is disabled (Htg Status= is “Off Man”).Heat OnlyWhen the Control Mode is set to “Heat Only”, heating operation is allowed to operate to maintain the heating set points. Cooling operation is disabled (Clg Status= is “Off Man”).

Fan OnlyWhen the Control Mode is set to “Fan Only”, the fans are allowed to operate but cooling and heating operation is disabled (Clg Status= and Htg Status= are “Off Man”).AutoWhen the Control Mode is set to “Auto”, the heat/cool, cool only, heat only, and fan only decision is determined by the Appl Mode= parameter, which is set via a network signal as described below. The Appl Mode= parameter has no effect on unit operation unless the Control Mode is set to “Auto.”

Appl Mode

The unit heating and cooling can be set up for automatic heat/cool, heat only, cool only or fan only operation based on a network signal by setting the Ctrl Mode= parameter to “Auto.” With the Ctrl Mode= parameter set to “Auto”, the heat/cool, cool only, heat only, and fan only decision is determined by the Application Mode. The Application Mode is set by a network signal. The following sections describe the five available Application Mode selections.

Note: The Application Mode has no effect on the unit operation unless the Ctrl Mode= parameter is set to “Auto.”

OffWhen the Application Mode is set to “Off”, the UnitStatus= is “Off Net” and the unit is completely disabled, including

WARNINGElectric shock and moving machinery hazard. Can cause personal injury or death.

When the unit is in any Off operating state, power is not removed from the unit controller or components. Remove power by turning off the disconnect-switch before servicing line voltage equipment or entering the unit.

Table 9: Programmable Parameters

Keypad/Display IDParameter Name

Menu Name Item Name

System Ctrl Mode= Off Control Mode



Menu Name Item Name

System Appl Mode= Heat/Cool Application Mode

52 OM-137-2

unoccupied heating (night set back) and unoccupied cooling (night set up) operation.Heat/CoolWhen the Application Mode is set to “Heat/Cool”, both cooling and heating operation are allowed to operate as required to maintain the cooling and heating set points.Cool OnlyWhen the Application Mode is set to “Cool Only”, cooling operation is allowed to operate as required to maintain the cooling set points. Heating operation is disabled (Htg Status= is “Off Net”).Heat OnlyWhen the Application Mode is set to “Heat Only”, heating operation is allowed to operate as required to maintain the heating set points. Cooling operation is disabled (Clg Status= is “Off Net”).Fan OnlyWhen the Application Mode is set to “Fan Only”, the fans are allowed to operate but cooling and heating operation is disabled (Clg Status= and Htg Status= are “Off Net”).

OccupancyOccupancy= is a status item which indicates whether the unit is in an occupied or unoccupied mode of operation. The following are descriptions of the various “Occupancy” states.OccThe Occupancy= parameter indicates “Occ” when the unit is in the occupied mode. In this mode, the unit generally starts and runs continuously, cooling and heating as required to maintain the occupied temperature set points.1 The unit is in the occupied mode if any of the following conditions are true:1. The Occ Mode= parameter is set to “Occ.”2. The OccMode= parameter is set to “Auto” and a field

supplied external time clock or a tenant override switch signal in the form of a set of dry contacts is closed across terminals 101 and 102 on the unit field terminal block TB2 (binary input MCB-BI1 on). Note: Pacing the unit S7 switch into the “On” position makes terminals 101 and102 on TB2.For detailed information refer to “External Time Clock or Tenant Override (Non-Timed)” in IM 696, MicroTech II Applied Rooftop Unit Controller.

3. The Occ Mode= parameter is set to “Auto” and the unit internal time clock schedule, optimal start function, one time event schedule, or an optional network schedule indicates an occupied period.

UnoccThe Occupancy= parameter indicates “Unocc” when the unit is in the unoccupied mode. In the unoccupied mode, the unit is off and remains off unless unoccupied cooling (night set up or purge) or unoccupied heating (night set back) operation is activated. Refer to “Unoccupied Control” on page 114. The unit is in the unoccupied mode if the Occ Mode= parameter is set to “Unocc” or to “Auto” and none of three items listed above in the “Occ” section are true:

Note: The unit reverts to unoccupied mode if the calibrate function is active. For more information on cali-brate mode, refer to “Calibrate Mode” on page 64.

Tnt OvrdThe Occupancy= parameter indicates “Tnt Ovrd” when the unit is in the tenant override mode. In the tenant override mode the unit starts up and function as it does in occupied mode.1 The unit is in the tenant override mode if the Tnt Ovrd= parameter in the occupancy menu is set to a non-zero value. For details regarding how the Tnt Ovrd= is set, refer to “Tenant Override” on page 55.

Occ Mode

The unit can be set up for automatic or manual occupied/unoccupied operation by setting the Occupancy Mode. The following are descriptions of the four available Occupancy Mode selections.AutoWhen the Occupancy Mode is set to “Auto”, the unit operates automatically. This means that the Occupancy= parameter changes automatically between “Occ”, Unocc” and “Bypass”.The Occupancy= parameter indicates “Occ” and the unit starts if any of the following are true:1. The current time of day crosses a start time in the inter-

nal time scheduling function.2. The external time clock terminals 101 and 102 on termi-

nal block TB2 are made. Note: The terminals can be made by a field supplied switch or normally open set of contacts or by placing the unit S7 switch in the “On” position. Refer to “External Time Clock or Tenant Over-ride” in IM 696, MicroTech II Applied Rooftop Control-ler.

3. The unit optimal start function is activated.4. The one time event schedule function is activated.5. A network scheduling function indicates occupied

operation.

1. The unit will not start regardless of the occupancy mode when the UnitStatus= parameter indicates “Off Sw”, “Man Ctrl”, “Off Alm”, “Off Net”, or “Off Man”. For a description of these operating states, refer to “Operating State Descrip-tions” on page 71.



Menu Name Item Name

Occupancy Occ Mode= Auto Occupancy Mode

OM-137-2 53

The Occupancy= parameter indicates “Unocc” and the unit stops if all of the following are true:1. The current time of day crosses a stop time in the inter-

nal time scheduling function or the time scheduling function has never been activated.

2. The external time clock terminals 101 and 102 on termi-nal block TB2 are not made. Note: The terminals can be made by a field supplied switch or normally open set of contacts or by placing the unit S7 switch in the “On” position. Refer to “External Time Clock or Tenant Over-ride” in IM 696, MicroTech II Applied Rooftop Control-ler.

3. The unit optimal start function is inactive.4. The one time event schedule is inactive.5. Any network scheduling function indicates unoccupied

operation.Note: The unit can start up and run while the Occupancy= parameter indicates “Unocc” if the unoccupied heating (night set back) or unoccupied cooling (night set up or purge) functions are active. Refer to “Unoccupied Control” on page 114.Note: The Occupancy= parameter indicates “Unocc” and the unit stops if the Calibrate function is activated. Refer to “Calibrate Mode” on page 64.The Occupancy= parameter indicates “Tnt Ovrd” and the unit starts if the Tnt Ovrd= parameter in the Occupancy menu is set to a non-zero value1. For details regarding how the Tnt Ovrd= parameter is set, refer to “Tenant Override“.OccWhen the Occupancy Mode is set to “Occ”, the Occupancy= parameter indicates “Occ” and the unit starts and runs continuously in the occupied mode1. Any scheduling commands are prevented from shutting down the unit.

Note: The Occupancy= parameter indicates “Unocc” and the unit stops if the Calibrate function is activated. Refer to “Calibrate Mode” on page 64.

UnoccWhen the Occupancy Mode is set to “Unocc”, the Occupancy= parameter indicates “Unocc” and the unit is off and remains off unless unoccupied cooling (night set up or purge) or unoccupied heating (night set back) operation is activated. Refer to “Unoccupied Control” on page 1141. Tnt OvrdWhen the Occupancy Mode is set to “Tnt Ovrd”, the Tnt Ovrd= parameter in the Occupancy menu is set to the Tnt Ovrd= value in the Timer Settings menu. The Occupancy= parameter indicates “Tnt Ovrd” and the unit starts and operates as in the occupied mode until the Tnt Ovrd= parameter times out. Any scheduling commands are prevented from shutting down the unit while the tenant override operation is active.1

Note: Once the Occupancy Mode is set to “Tnt Ovrd” and the Tnt Ovrd= parameter in the Occupancy menu is set to the Tnt Ovrd= value in the Timer Settings menu, the Occupancy Mode automatically reverts to the “Auto” setting.

Note: The Occupancy= parameter indicates “Unocc” and the unit stops if the Calibrate function is activated. Refer to “Calibrate Mode” on page 64.


54 OM-137-2

OccSrcOccSrc= is a status item which indicates the input source or function that is responsible for setting the Occupancy= parameter to “Occ.” There are a number of things that can change the Occupancy= parameter to “Occ” and the Occ Src= parameter is very helpful in determining which function has started the unit.NoneThe Occ Src= parameter indicates “None” when the Occupancy= parameter indicates “Unocc” or “Tnt Ovrd.” Int SchedThe Occ Src= parameter indicates “Int Sched” when the Occupancy= parameter indicates “Occ” due to the unit internal schedule or one event schedule indicating an occupied period. Refer to “Scheduling” on page 56.Net SchedThe Occ Src= parameter indicates “Net Sched” when the Occupancy= parameter indicates “Occ” due to a network schedule indicating an occupied period.Occ ModeThe Occ Src= parameter indicates “Occ Mode” when the Occupancy= parameter indicates “Occ” due to the Occupancy Mode being manually set to “Occ.”Remote SwThe Occ Src= parameter indicates “Remote Sw” when the Occupancy= parameter indicates “Occ” due to a field supplied external time clock or a tenant override switch signal in the form of a set of dry contacts is closed across terminals 101 and 102 on the unit field terminal block TB2 (binary input MCB-BI1 on). For detailed information refer to “External Time Clock or Tenant Override (Non-Timed)” in IM 696, MicroTech II Applied Rooftop Unit Controller.

Tenant Override

There are two types of tenant override functions: timed and non-timed. Timed override uses the Tenant Override Timer and Tenant Override Time Increment to place the unit into tenant override mode. Non-timed override uses a simple field supplied SPST switch between override and unoccupied operation. Timed Tenant OverrideThe tenant-override button provided with the optional zone temperature sensor packages is used to override unoccupied

operation for a pre programmed time period. This time period is set with the Tenant Override Time Increment. This value can be adjusted from 0 to 300 minutes (default is 120 minutes).When an occupant presses and releases the tenant override button on the zone temperature sensor (ZNT1), the Tenant Override Timer is set equal to the Tenant Override Time Increment. (The button must be held for at least 1 second but not more than 30 seconds.) The unit then starts and runs in the tenant override mode which is the same as occupied mode except that it is temporary.1 The Tenant Override Timer begins timing out and the unit runs until the timer expires. If the tenant override button is pressed again while the unit is operating in tenant override mode, the Tenant Override Timer is reset to the Tenant Override Time Increment and the unit continues to operate. For example, assume that the Tenant Override Time Increment is 120 minutes. One press of the override button provides at least 120 minutes of unit operation. If the button is pressed again 60 minutes later, the Tenant Override Timer is reset to 120 minutes, and a total of 180 minutes of uninterrupted operation results.

Note: The same operation occurs if, instead of pressing the override button on a zone temperature sensor, the Occupancy Mode is set to “Tnt Ovrd.” Once set to “Tnt Ovrd”, the Occupancy Mode automatically reverts to the “Auto” setting once the Tnt Ovrd Timer is set to the Tnt Ovrd Time Increment.

Non-Timed Tenant OverrideIf an field supplied external time clock or a tenant override switch signal in the form of a set of dry contacts is closed across terminals 101 and 102 on the unit field terminal block TB2 (binary input MCB-BI1 on), the unit is placed into occupied mode1. When this switch is open, the unit is controlled by any active scheduling function (internal time clock schedule, optimal start function, one time event schedule, or an optional network schedule). If there is no active scheduling function, the unit remains in the unoccupied mode. For detailed information refer to “External Time Clock or Tenant Override (Non-Timed)” in IM 696, MicroTech II Applied Rooftop Unit Controller.Operator OverrideThe Tenant Override Timer can be manually set. When the Tenant Override Timer is set to a non-zero value, the unit starts and runs in the tenant override mode regardless of any scheduling features.1 The unit stops when the timer expires. The Tenant Override Timer can be set from 0-300 minutes.

Note: If the Tenant Override Timer remaining time is larger than the Tenant Override Time Increment,



Menu Name Item Name

OccupancyOcc Mode= Auto Occupancy ModeTnt Ovrd= 0 min Tenant Override Timer

Timer Settings Tnt Ovrd = 120 min Tenant Override Time Increment


OM-137-2 55

pressing the tenant override button on the space sensor has no effect. If the Tenant Override Timer remaining time is less than the Tenant Override Time Increment, pressing the tenant override button resets the Tenant Override Timer to the Tenant Override Time Increment value.

Emergency Override

The unit can be shutdown by setting the Emergency Override Mode Flag. When the Emergency Override Mode Flag is set to “Off”, the UnitStatus= parameter indicates “Off Net” and the unit remains off regardless of any time schedule or other occupied or unoccupied start commands. The only way a unit can be restarted is to set Emergency Override Mode Flag back to “Norm.” The Emergency Override Mode Flag can either be set manually at the unit keypad or via a network signal.

SchedulingThe rooftop unit can be scheduled for operation by using the following three methods:1) Unit internal time scheduling functions2) External time clock function3) Network time scheduling functionProvided the unit is not locally or remotely disabled, the unit operates when any of these scheduling functions is calling for occupied operation. Conversely, the unit enters the unoccupied mode when all of these scheduling functions are calling for unoccupied operation. Therefore, any unused scheduling functions should be set for continuous unoccupied operation. Refer also to“Auto/Manual Operation” on page 52.The next four sections: “Setting Controller Date and Time”, “Internal Daily Scheduling”, “Holiday Scheduling”, and One Event Scheduling” describe functions related to the internal unit scheduling functions. These are followed by a section describing the optimal start function which can be use with internal scheduling and network scheduling. This is followed by two sections that describe the external time scheduling and network time scheduling functions.

Setting Controller Date and Time

The MicroTech II controller uses the date and time to execute its internal scheduling functions. Once set, the battery backed internal time clock keeps the current time regardless of whether or not power is being supplied to the unit.

Note: The controller date and time may revert to an archived value if power is interrupted to the con-troller and the controller battery is defective or not installed.

The time of day can be set by entering the hour (00-23), minute (00-59), and second (00-59) into three fields of the Current Time. Note that MicroTech II uses “military” time. The day of the week is not adjustable. The Current Day is set automatically by the controller based on the Current Date. The current date can be set by entering the date (00-31), month (01-12) and year (1999-2155) into the three fields of the Current Date.

Internal Daily Scheduling

When the Occ Mode= parameter, described in “Auto/Manual Operation” on page 52, is set to “Auto”, and the unit is not disabled for other reasons, it starts and stops according to the controller internal schedule. One start and one stop time can be set for each day of the week and for designated holidays. An example of how to use the keypad to enter or modify a schedule is given in “Getting Started” on page 6.As shown in Figure 5, each daily schedule has four adjustable fields: Start Hour, Start Minute, Stop Hour, and Stop Minute. The schedule shown would cause the unit to



Menu Name Item Name

Occupancy Emerg Override= Norm Emergency Override Mode Flag



Menu Name Item Name

Time/DateTime= hh:mm:ss Current Time

Day= ddd Current DayDate= dd-mm-yyyy Current Date



Menu Name Item Name

Daily Schedule

Mon= 00:00 - 00:00 Monday ScheduleTue= 00:00 - 00:00 Tuesday ScheduleWed= 00:00 - 00:00 Wednesday ScheduleThu= 00:00 - 00:00 Thursday ScheduleFri= 00:00 - 00:00 Friday ScheduleSat= 00:00 - 00:00 Saturday ScheduleSun= 00:00 - 00:00 Sunday ScheduleHol= 00:00 - 00:00 Holiday Schedule

56 OM-137-2

start up at 6:30 a.m. and shut down at 6:00 p.m. every Monday, Tuesday and Wednesday.

Figure 5: Daily Schedule Fields

Notes:1. A unit will start based on a daily schedule only if the

Current Time= value actually crosses a start time for the given day. For example, if the current day start and stop time were set to 06:00 - 18:00 at 10:00 in the morning on that day, the unit would not start because Current Time= value would not cross the 06:00 start time.

2. A unit will stop based on a daily schedule only if the Current Time= value actually crosses a non-zero stop time for the given day. For example, if a unit were run-

ning based on a 06:00 - 18:00 schedule on a given day and the stop time for that day were the set to 00:00 before the Current Time= value crossed 18:00, the unit would not stop on that day.

3. For no unit operation for an entire day, the schedule fields for that day should be set to “00:00-00:00”.

4. For continuous unit operation, the start time for the first day of required operation should be set to the desired start time and the stop time for the last day of required operation should be set to the desired stop time. All start and stop times in between should be left at 00:00. For example, if a unit needed to run continuously Monday through Friday and remain off over the weekend, the following schedule settings would be used:Mon= 00:01-00:00Tue = 00:00-00:00Wed = 00:00-00:00Thu = 00:00-00:00Fri = 00:00-23:59Sat = 00:00-00:00Sun = 00:00-00:00 Hol = 00:00-00:00

**Edit ModeMon= 06:30 - 18:00Tue= 06:30 - 18:00Wed= 06:30 - 18:00

Menu Line

Item Line Being Edited

Start Hour

Start Minute

Stop Hour

Stop Minute

OM-137-2 57

Holiday Scheduling

Special operating hours can be scheduled for up to 16 holiday periods during the year by using the holiday scheduling feature. (The wildcard character “*” in the above table could be any number between 1 and 16.) Whenever a holiday period occurs, the controller uses the Holiday Schedule start and stop time for the period. For example, assume that Christmas Eve occurs on a Thursday. The building is shut down on both Christmas Eve and Christmas Day, but operates normally on the weekend. This holiday period would be scheduled by setting the Holiday Schedule to “00:00-00:00” and setting the Holiday Period to “Dec 24 - Dec 25.”If any of the 16 holiday periods are not required, the Holiday Period is set to “N/A - N/A.”

One Event Scheduling

The unit can be scheduled to operate during a specified period by using the one event scheduling feature. During the

specified period defined by the One Event Beginning Date/Time and One Event Ending Date/Time parameters the unit starts up and runs continuously regardless of any other time scheduling functions. For example, assume that a space served by the unit is occupied for a special event on March 12 from 5:00 p.m. to 10:00 p.m. when the normal time scheduling has the unit shut off after 4:00 p.m. on that date. This event can be accounted for by setting the One Event Beginning Date/Time to “Mar 12 @ 17:00” and the One Event Ending Date/Time to “Mar 12 @ 22:00.” If a one-event schedule is not required, the One Event Beginning Date/Time and One Event Ending Date/Time parameters are both set to “N/A.”

Optimal StartThe optimal start function can only be used with the unit internal time schedule or a network supplied time schedule that indicates “time-to-occupancy”. When the Optimal Start Flag is set to “Yes”, the controller calculates an early start time before each normally scheduled start. The controller uses the start history, outdoor air temperature, and space temperature to determine when the unit should start. The unit may be started by the optimal start function up to four hours before the scheduled start time.If the Ctrl Temp= parameter, which is the temperature input selected by the CtrlTemp Src= parameter, is below the Effective Heating Enable Set Point by more than half the Heating Enable Deadband setting, optimal start operation is based on the optimal start heating parameters. If the Ctrl Temp= value is above the Effective Cooling Enable Set Point by more than half Cooling Enable Deadband setting, optimal start operation is based on the optimal start cooling parameters. Unit startup occurs at the scheduled start time if the Ctrl Temp= value is in between these limits.

When heating is required, a “heating rate” that varies with the outdoor air temperature is calculated using the formula:



Menu Name Item Name

Daily Schedule Holiday= 00:00 - 00:00 Holiday ScheduleHoliday Schedule Hol *= mmm dt - mmm dt Holiday Period



Menu Name Item Name

One EventBeg= mmm dd @ hh:mm One Event Beginning

Date/Time

End= mmm dd @ hh:mm One Event Ending Date/Time

Table 18: Programmable Parameter


Menu Name Item Name

Zone CoolingEff Clg Spt= 75.0 ºF Effective Cooling Enable Set Point

Clg Deadband= 1.0 ºF Cooling Enable Deadband

Zone HeatingEff Htg Spt= 75.0 ºF Effective Heating Enable Set Point

Htg Deadband= 1.0 ºF Heating Enable Deadband

Optimal Start

Optimal Start= No Optimal Start FlagAuto Update= Yes Automatic Update Flag

Htg Rate= 0.4 ºF/min Heating RateHtg OAT= 35.0 ºF Heating Outdoor Air Temperature

Htg Zero OAT= 0 ºF Heating Outdoor Air Temperature ZeroClg Rate= 0.4 ºF/min Cooling Rate

Clg OAT= 85.0 ºF Cooling Outdoor Air TemperatureClg Zero OAT= 100 ºF Cooling Outdoor Air Temperature Zero

58 OM-137-2

The minutes before occupancy are calculated based on the following formula:

When cooling is required, a “cooling rate” that varies with the outdoor air temperature is calculated using the formula:

The minutes before occupancy are calculated using the following formula:

If the Automatic Update Flag is set to “Yes”, the controller revises the optimal start parameters after each start in which they are used and the temperature change is significant.

External Time SchedulingAn external time clock can be used to schedule unit operation. This is accomplished by a field supplied external time clock signal in the form of a set of dry contacts wired across terminals 101 and 102 on the unit field terminal block TB2 (binary input MCB-BI1). In this case, all internal daily schedules should be set to “00:00-00:00” (default setting). For details on how to connect an external time clock, refer to “Field Wiring” in IM 696, MicroTech II Applied Rooftop Unit Controller.

Network Time SchedulingA network time schedule can be used to operate the unit. In this case, all internal daily schedules should be set to “00:00-00:00” (default setting). Scheduling a unit via a network signal is supported through optional communication modules (BACnet®/IP, BACnet MS/TP and LonMark®).

Alarm MonitoringAbout AlarmsThe MicroTech II Applied Rooftop Unit Controller is programmed to monitor the unit for alarm conditions. Alarm conditions are categorized in three types: “faults”, “problems”, and “warnings.” In general, “faults” are more serious than “problems” and “problems” more serious that “warnings.” Therefore, “faults” are assigned a higher priority than “problems” and “problems” a higher priority than “warnings.” Within the three types, the alarms are prioritized. Some alarms require manual clearing and some are cleared automatically. Table 19 summarizes all alarms, listing them by type and priority, and listing the required clearing method.If an alarm condition occurs, the controller displays a message and executes the appropriate action to make the unit fail-safe. The controller displays a local message on the unit keypad/display and a remote indication via a Remote Alarm Output (binary output MCB-BO4) wired to terminals for field connection. For the meaning of each alarm, see “Alarm Control” on page 115.

Calculated Heating Rate Heating Rate Current OA Temperature Heating Outdoor Air Temperature Zero–Heating Outdoor Air Temperature Heating Outdoor Air Temperature Zero–---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------×=

Minutes Before Occupancy Effective Heating Enable Set Point Current Space Temperature–Calculated Heating Rate

------------------------------------------------------------------------------------------------------------------------------------------------------------=

Calculated Cooling Rate Cooling Rate Cooling Outdoor Air Temperature Zero Current OA Temperature–Cooling Outdoor Air Temperature Zero Cooling Outdoor Air Temperature–---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------×=

Minutes Before Occupancy Current Space Temperature Effective Cooling Enable Set Point–Calculated Cooling Rate

------------------------------------------------------------------------------------------------------------------------------------------------------------=

Table 19: Unit Alarms

Alarm Type Alarm Message Indication Alarm Reset

Fault

Freeze Freezestat condition while SAF on ManualSmoke Smoke detected by SAF and/or RAF smoke detector Manuala

OAT Sensor OAT sensor failure when Cntl Temp Src= parameter is set to “OAT” ManualSpace Sensor Space temp sensor failure when CtrlTemp Src= parameter is set to “Space” ManualReturn Sensor RAT sensor failure ManualDisch Sensor DAT sensor failure ManualDuct Hi Limit Excessive discharge compartment pressure sensed by DHL sensor Manual

Hi Return Tmp RAT exceeded the Hi Return Tmp setting ManualHi Disch Tmp DAT exceeded the Hi Disch Tmp setting ManualLo Disch Tmp DAT fell below the Lo Disch Tmp setting Manual

Fan Fail Airflow not sensed by PC7 after SAF was started ManualOA Dmpr Stuck OA Dampers < 50% open after Startup (100% OA units only) Manual

OM-137-2 59

Remote Alarm IndicationThe MicroTech II control system includes a Remote Alarm Output (MCB-B04) to provide remote indication of alarm conditions. Under normal (no active alarm) conditions, the Remote Alarm Output (MCB-B04) is closed. The LED associated with the alarm output indicates the state of the output: On indicates MCB-B04 is closed, and off indicates MCB-B04 is open. The Remote Alarm Output can be connected to a field-supplied annunciator. If an alarm occurs, the Remote Alarm Output condition changes to either an “off” or “blinking” state. Each possible alarm condition can

be set up to cause the output to either blink rapidly, blink slowly, turn off or remain on (no remote indication of the alarm). Refer to “Configuring Remote Alarm Output.” on page 63.

Note: If there are multiple active alarms, only the highest priority alarm affects this output. This is always the alarm indicated by the Active Alarm 1 menu. Refer to “Remote Alarm Output” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.

Problem

Freeze Freezestat tripped while SAF was off AutomaticOAT Sensor OAT sensor failure when CtrlTemp Src= parameter not set to “OAT” Automatic

Space Sensor Space temp sensor failure on unit with RAT sensor AutomaticReturn Sensor RAT sensor failure when CtrlTemp Src= parameter not set to “Return” AutomaticEnt Fan Sensor EFT sensor failure Automatic

Lo Airflow Excessive temperature rise sensed across heat section on single stage heat unit ManualHeat Fail Gas furnace safety lockout condition occurred Automaticb

Fan Retry Airflow not sensed by PC7 after SAF was started AutomaticHi Pres-Ckt1 HP1 or HP3 open indicating ckt # 1 high refrigerant pressure ManualHi Pres-Ckt2 HP2 or HP4 open indicating ckt # 2 high refrigerant pressure ManualLo Pres-Ckt1 LP1 remained opened after ckt #1 solenoid valve open Automaticc

Lo Pres-Ckt2 LP2 remained opened after ckt #2 solenoid valve open Automaticc

Frost-Ckt1d Evaporator coil frost condition occurred on ckt #1 Automaticc

Frost-Ckt2d Evaporator coil frost condition occurred on ckt #2 Automaticc

Comp #1 Alm Comp #1 off on low oil pressure (OP1) or motor protector (MP1) Automaticc




PumpDown-Ckt1 LP1 still closed 180 seconds into ckt #1 pumpdown operation ManualPumpDown-Ckt2 LP2 still closed 180 seconds into ckt #2 pumpdown operation Manual

Ckt1 Clg Ena Clg enable input to CCB1 off when cooling was on ManualCkt2 Clg Ena Clg enable input to CCB2 off when cooling was on Manual

GenC Clg Ena Clg enable input to GCB1 off when cooling was on ManualHtgB Htg Ena Htg enable input to EHB1 off when heating was on Manual

Ckt1 Comm Fail Comm failure occurred between MCB and CCB1 AutomaticCkt2 Comm Fail Comm failure occurred between MCB and CCB2 Automatic

GenC Comm Fail Comm failure occurred between MCB and GCB1 AutomaticHtgB Comm Fail Comm failure occurred between MCB and EHB1 Automatic

ERecB Comm Fail Comm failure occurred between MCB and ERB1 Automatic

Warning

Airflow Switch PC7 sensed airflow when unit was off ManualDirty Filter Pressure drop across first filter section exceeded the setting of PC5 Manual

Dirty FnlFltr Pressure drop across final filter section exceeded the setting of PC6 ManualCkt1 H/W Clg enable input to CCB1 on when cooling off ManualCkt2 H/W Clg enable input to CCB2 on when cooling off Manual

GenC H/W Clg enable input to GCB1 on when cooling off ManualHtgB H/W Htg enable input to EHB1 on when heating off Manual

a. The SAF and RAF smoke detectors must be manually reset after tripping. This can be accomplish be cycling control system power (S1 Switch).b. A manual reset of the flame safeguard control FSG is required before the Heat Fail problem clears.c. Manual clearing is required if this alarm occurs three times within a 24-hour period (2:00 a.m. of one day until 2:00 a.m. of the next). The oil pressure safety devices require a

manual reset on the device.d. Not applicable on units equipped with hot gas bypass.

Table 19: Unit Alarms (Continued)

Alarm Type Alarm Message Indication Alarm Reset

60 OM-137-2

Figure 6: Active and Previous Alarm Menu Display

Local Alarm Indication (Keypad/Display)Alarm information is provided via the unit keypad/display by four “active” and eight “previous” alarm menus.Up to four active alarms are displayed in the Active Alarm 1, Active Alarm 2, Active Alarm 3, and Active Alarm 4 menus. The highest priority active alarm is displayed in the Active Alarm 1 menu, the second highest priority active alarm in the Active Alarm 2, the third highest priority active alarm in the Active Alarm 3 and the forth highest priority active alarm in the Active Alarm 4 menu. If it happens that there are more than four active alarms, the additional alarms do not appear until one of these four active alarms are cleared.When an active alarm is cleared the remaining active alarms are resorted such that the highest priority active alarm remaining is displayed in Active Alarm 1, the second highest priority active alarm remaining is displayed in Active Alarm 2 and so forth. Figure 6 shows the typical display of an active alarm menu. The first line of the display is the menu line, the second line indicates the alarm name, the third line indicates the alarm “type” (fault, problem, or warning) and the forth line indicates the date and time the alarm occurred. Whenever there is an active alarm, a red alarm LED on the unit keypad turns on. If there are no active alarms, this LED remains off.When an active alarm is cleared, it is stored in the Previous Alarm 1 menu. Any alarm that might be in the Previous Alarm 1 menu is moved to the Previous Alarm 2 menu, any alarm that might be in the Previous Alarm 2 menu is moved to the Previous Alarm 3 menu and so forth. Any alarm that might be in the Previous Alarm 8 menu is permanently remove from the keypad. Figure 6 shows a typical display of a previous alarm menu. The first line of the display is the menu line, the second line indicates the alarm name, the third line indicates the alarm “type” (fault, problem, or warning) and the forth line indicates the date and time the alarm occurred.Displaying AlarmsActive Alarms. When an active alarm exists the red LED on the keypad is on. The active alarm or alarms can be viewed as follows:

1. Pressing the Alarm key while the red LED on the key-pad is on changes the display to the Active Alarm 1 menu.

2. Pressing the Right Arrow key changes the display to the Active Alarm 2 menu. Pressing the Right Arrow key again changes the display to the Active Alarm 3 menu. Pressing the Right Arrow key again changes the display to the Active Alarm 4 menu.

3. Pressing the Left Arrow key changes the display back to the Active Alarm 3 menu. Repeating this key two more times changes the display back to the Active Alarm 1 menu.

Previous Alarm. When active alarms are cleared, they are stored in the previous alarm menus. The previous alarm menus can be viewed as follows:

1. Pressing the Back/Cancel key changes the display to back to the main menu if not already there.

2. Assuming the blinking cursor is positioned on the Sys-tem Summary menu, pressing the Down Arrow (-) key six times changes the cursor position to the Previous Alarms menu.

3. Pressing the Enter/Save key changes the display to the Previous Alarm 1 menu.

4. Pressing the Right Arrow key changes the display to the Previous Alarm 2 menu. Pressing the Right Arrow key again changes the display to the Previous Alarm 3

Active Alarm 1Dirty FilterWarning-Active12-Mar-00 04:50:49

Menu Line

Alarm Name Item Line

Alarm Type Item Line

Alarm Date/Time Item Line

Previous Alarm 1Dirty FilterWarning-Clear12-Mar-00 05:15:34

OM-137-2 61

menu. Pressing the Right Arrow key five more times changes the display to the Previous Alarm 8 menu.

5. Pressing the Left Arrow key changes the display back to the Active Alarm 7 menu. Repeating this six more times changes the display back to the Previous Alarm 1 menu.

Clearing Alarms. Before any active alarm is cleared, the alarm conditions that caused it must have returned to normal. When the alarm conditions are no longer present, an active alarm may be cleared either automatically or manually.

Note: Some of the safety devices that detect alarm condi-tion require a manual reset at the device before the alarm can be cleared. Refer to Table 19 on page 59 for listing of possible alarms and to determine whether an alarm is manual or automatic reset.

An automatic reset active alarm immediately clears when the alarm conditions that caused it disappear. A manual reset active alarm is cleared using the keypad/display as follows.1. The active alarm to be cleared is first displayed. Refer to

“Displaying Alarms” on page 61.

2. Pressing the Clear Alarm key while the active alarm to be cleared is in the display sends a clear command to the

controller. This clears the active alarm and returns the unit to normal operation if no other alarms are active.

Remote Alarm ClearingAlthough it is always recommended that active alarms be cleared at the unit via the keypad/display, there are other methods that effectively clear active alarms. Three such methods are described in the following sections.Unit System Switch (S1)Cycling the main controller system switch (S1) located in the unit main control panel has the effect of clearing the active alarm menus. The disadvantage of clearing alarms in this manor is that the active alarm data is not placed into the previous alarm buffer and alarm information is lost.

Note: Turning off the unit power disconnect switch has the same effect.

Manual Unit Enable/Disable Input Disabling the unit via the manual unit enable/disable input (this occurs when a field supplied and installed switch across terminals 101 and 104 on the unit field terminal block (TB2) is changed from the on (closed) to off (open) position. Refer to the “Manual Unit Enable/Disable” section of IM 696, MicroTech II Applied Rooftop Unit Controller.Network SignalThe active alarms can be cleared via a network signal through optional communication modules (including BACnet®/IP, BACnet MS/TP and LonMark®).

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Configuring Remote Alarm Output.Table 20: Programmable Parameters


Menu Name Item Name

Alarm Out Faults

Freeze= Fast Freeze Fault Remote Output SetupSmoke= Fast Smoke Fault Remote Output Setup

OAT Sensor= Fast OAT Sensor Fault Remote Output SetupSpace Sensor= Fast Space Sensor Fault Remote Output SetupReturn Sensor= Fast Return Sensor Fault Remote Output Setup Disch Sensor= Fast Disch Sensor Fault Remote Output SetupDuct Hi Limit= Fast Duct Hi Limit Fault Remote Output Setup

Hi Return Tmp= Fast Hi Return Tmp Fault Remote Output SetupHi Disch Tmp= Fast Hi Disch Tmp Fault Remote Output SetupLo Disch Tmp= Fast Lo Disch Tmp Fault Remote Output Setup

Fan Fail= Fast Fan Fail Fault Remote Output SetupOA Dmpr Stuck= Fast OA Dmpr Stuck Fault Remote Output Setup

Alarm Out Problems

Freeze= Slow Freeze Problem Remote Output SetupOAT Sensor= Slow OAT Sensor Problem Remote Output Setup

Space Sensor= Slow Space Sensor Problem Remote Output SetupReturn Sensor= Slow Return Sensor Problem Remote Output SetupEnt Fan Sensor= Slow Ent Fan Sensor Problem Remote Output Setup

Lo Airflow= Slow Lo Airflow Problem Remote Output SetupHeat Fail= Slow Heat Fail Problem Remote Output SetupFan Retry= Slow Fan Retry Problem Remote Output Setup

Hi Pres-Ckt1= Slow Hi Pres-Ckt1 Problem Remote Output SetupHi Pres-Ckt2= Slow Hi Pres-Ckt2 Problem Remote Output SetupLo Pres-Ckt1= Slow Lo Pres-Ckt1 Problem Remote Output SetupLo Pres-Ckt2= Slow Lo Pres-Ckt2 Problem Remote Output Setup

Frost-Ckt1= Slow Frost-Ckt1 Problem Remote Output SetupFrost-Ckt2= Slow Frost-Ckt2 Problem Remote Output Setup

Comp #1 Alm= Slow Comp 1 Alm Problem Remote Output SetupComp #2 Alm= Slow Comp 2 Alm Problem Remote Output SetupComp #3 Alm= Slow Comp 3 Alm Problem Remote Output SetupComp #4 Alm= Slow Comp 4 Alm Problem Remote Output SetupComp #5 Alm= Slow Comp 5 Alm Problem Remote Output SetupComp #6 Alm= Slow Comp 6 Alm Problem Remote Output Setup

PumpDown-Ckt1= Slow PumpDown-Ckt1 Problem Remote Output SetupPumpDown-Ckt2= Slow PumpDown-Ckt2 Problem Remote Output Setup

Ckt1 Clg Ena= Slow Ckt1 Clg Ena Problem Remote Output SetupCkt2 Clg Ena= Slow Ckt2 Clg Ena Problem Remote Output Setup

GenC Clg Ena= Slow GenC Clg Ena Problem Remote Output SetupHtgB Htg Ena= Slow HtgB Htg Ena Problem Remote Output Setup

Ckt1 Comm Fail= Slow Ckt1 Comm Fail Problem Remote Output SetupCkt2 Comm Fail= Slow Ckt2 Comm Fail Problem Remote Output Setup

GenC Comm Fail= Slow GenC Comm Fail Problem Remote Output SetupHtgB Comm Fail= Slow HtgB Comm Fail Problem Remote Output Setup

ERecB Comm Fail= Slow ERecB Comm Fail Problem Remote Output Setup

Alarm Out Warnings

Airflow Switch= Off Airflow Switch Warning Remote Output SetupDirty Filter= Off Dirty Filter Warning Remote Output Setup

Dirty FnlFltr= Off Dirty FnlFltr Warning Remote Output SetupCkt1 H/W= Off Ckt1 H/W Warning Remote Output SetupCkt2 H/W= Off Ckt2 H/W Warning Remote Output Setup

GenC H/W= Off GenC H/W Warning Remote Output SetupHtgB H/W= Off HtgB H/W Warning Remote Output Setup

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Each possible alarm condition can be configured to cause the Remote Alarm Output (MCB-B04) to blink rapidly, blink slowly, turn off, or remain on (no remote indication of the alarm). This allows the action of the Remote Alarm Output to be “tailored” according to the specific requirements of the application. When there are no active alarms within the controller the Remote Alarm Output is “on” continuously. If an alarm output setup parameter is set to “Slow”, the Remote Alarm Output cycles on and off at a slow rate when the alarm occurs. If an alarm output setup parameter is set to “Fast”, the Remote Alarm Output cycles on and off at a rapid rate when the alarm occurs. If an alarm output setup parameter is set to “Off”, the Remote Alarm Output turns off when the alarm occurs. If an alarm output setup parameter is set to “On”, the Remote Alarm Output remains on when the alarm occurs.For example, it may be necessary that only alarms that shut a unit off completely (faults) be indicated remotely. In this case all of the “fault” alarms are set to “Slow”, “Fast” or “Off.” All others are set to “On.” Refer to “Remote Alarm Output” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit ControllerSetting Alarm Limits

Three of the alarm faults have adjustable limits that are used to trigger the alarm. These are the Hi Disch Tmp, Lo Disch Tmp and Hi Return Tmp faults. Although the default settings should be suitable for most applications, the alarm limits can be set as necessary via the unit keypad/display. The default settings are shown in the table above.

Unit Configuration/Service ParametersCalibrate Mode

Calibrate Mode is a special service mode used to calibrate control actuator feedback signals and to zero static pressure

sensor inputs. When the Calibrate Mode Flag is set to “Yes”, the position feedback potentiometers on the outdoor air damper, discharge fan inlet vane, return or exhaust fan inlet vane, modulating cooling valve and modulating heating valve actuators are automatically calibrated. All the unit static pressure transducers are also calibrated (or zeroed). The following is a description of the Calibrate Mode procedure.When the Calibrate Mode Flag is set to “Yes”, the Occupancy= parameter is overridden and is set to “Unocc” and accordingly the unit shuts off. When the unit is off the outdoor air dampers, discharge vanes, return or exhaust vanes, modulating cooling valve, and modulating heating valve actuators are driven to the 100% open position for three minutes. After three minutes, the controller records the analog input feedback values from the actuators as equivalent to their fully open positions. The controller then drives the actuators to the opposite or fully “closed” position for three minutes. After three minutes, the controller records the analog input feedback values from the actuators as equivalent to their fully closed positions. The controller also records the analog input voltage signals from all connected pressure transducers as equivalent to 0 “W.C.

Note: It is best to calibrate the unit with all the sensing tubing to the static pressure sensors disconnected. This assures that the sensors are truly seeing 0 “WC when calibrated.

After the Calibrate Mode procedure is complete, the Ctrl Mode= parameter is set to “Off” which means the unit remains off until the Ctrl Mode= parameter is set to something other than “Off” as described in “Auto/Manual Operation” on page 52

Note: If the Calibrate Mode Flag is set to “Yes” while the Manual Control= parameter in the Manual Control menu is set to “Yes”, the Manual Control= parame-ter reverts to “No.” Similarly, if the Fan Balance= parameter in the Fan Balance menu is set to “On”, it reverts to “Off” if the Calibrate Mode Flag is set to “Yes.”

Zone (Space) Temperature Sensor

An optional zone (space) temperature sensor can be installed in the field and wired to the unit. When the optional sensor is installed, the Space Sensor Present Flag should be set to “Yes.” When the optional sensor is not installed, the Space Sensor Present Flag must be set to “No” to deactivate alarm functions associated with an open circuit at the space



Menu Name Item Name

Alarm Limits

Hi Disch Alm= 170 ºF High Discharge Air Temperature Alarm Limit

Lo Disch Alm= 40 ºF Lo Discharge Air Temperature Alarm Limit

Hi Return Alm= 120 ºF High Return Air Temperature Alarm Limit



Menu Name Item Name

Unit Configuration Calibrate Mode= No Calibrate Mode Flag



Menu Name Item Name

Unit Configuration Space Sensor= Yes Space Sensor Present Flag

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temperature analog input to the controller. The factory setting for the Space Sensor Present Flag is “Yes.” The optional space temperature sensor is required to take advantage of the MicroTech II unoccupied heating (night setback) and cooling (night setup and purge) functions. These functions are disabled when the Space Sensor Present Flag is set to “No.” Also, discharge air temperature set point reset based on space temperature, optimal start and the option of setting the CtrlTemp Src= parameter to “Space” are not available when the Space Sensor Present Flag is set to “No.”Refer to “Zone Temperature Sensor Packages” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.

Miscellaneous Service Parameters

The Unit Configuration menu contains several miscellaneous control parameters as listed in the table above. These parameters are generally the type that are set at the factory and might be adjusted when the equipment is started up and generally do not required further adjustment. The following sections describe these parameters.EFT SensorWhen a unit is equipped with gas or electric heat, it is equipped with an entering fan temperature (EFT) sensor. This sensor senses the temperature of the air entering the discharge air fan and is compared to the unit discharge air temperature to obtain an indication of the temperature rise across the gas or electric heat section. The controller uses this information to assure the heat rise across the heater does not exceed the safe limit for the heat exchanger. When the entering fan temperature sensor is installed the Entering Fan

Sensor Present Flag is set to “Yes.” When the entering fan temperature sensor is not installed the Entering Fan Sensor Present Flag is set to “No.” Setting this parameter to “No” disables the alarm function associated with an open circuit at the EFT temperature sensor input.2nd P SensorThe Second Pressure Sensor Present Flag is used to indicate whether or not an optional static pressure sensor is installed in the “second sensor” input location. When this parameter is set to “Duct”, the controller assumes there is a duct static pressure sensor installed in the “second sensor” location. In this case, the controller controls the unit discharge inlet vanes or VFD based on the lower of the two input values. When this parameter is set to “Bldg”, the controller assumes there is a building static pressure sensor installed in the “second sensor” location. In this case the unit return inlet vanes or VFD (VAV or CV units) are controlled to maintain the building static pressure at a building pressure set point. When this parameter is set to “None”, the controller assumes there is not a second static pressure sensor installed and ignores the associated analog input. For detailed information regarding discharge and return fan capacity control, refer to “Discharge Fan Capacity Control” on page 108 and “Return Fan Capacity Control” on page 109.DF CapCtrlThe Discharge Fan Capacity Control Flag is used to select the type of discharge fan capacity control on a VAV unit. If this parameter is set to “DuctPres”, the discharge fan capacity is controlled to maintain the duct static pressure at the duct static pressure set point. If this parameter is set to “Position”, duct static pressure control is overridden and the discharge fan capacity is controlled to the Remote Discharge Fan Capacity Set Point. For detailed information regarding discharge fan capacity control, refer to “Discharge Fan Capacity Control” on page 108.Remote DF CapThe the discharge fan capacity is controlled to maintain the Remote Discharge Fan Capacity Set Point when the Discharge Fan Capacity Control Flag is set to “Position”. Duct static pressure control of the discharge fan capacity is overridden. The Remote Discharge Fan Capacity Set Point is normally adjusted via a network signal but can also be adjusted via the keypad/display in the absence of a network tie to the parameter. For detailed information regarding discharge fan capacity control, refer to “Discharge Fan Capacity Control” on page 108.RF/EF CtrlThe Return/Exhaust Fan Capacity Control Flag is used to select the type of return or exhaust fan capacity control to be used. When this parameter is set to “Tracking”, the return fan capacity is controlled based on an adjustable tracking relationship between the discharge fan and return fan capacity. If this parameter is set to “Bldg”, then the return or exhaust fan capacity is controlled independently of the



Menu Name Item Name

Unit Configuration

EFT Sensor= No Entering Fan Sensor Present Flag

2nd P Sensor= None Second Pressure Sensor Present Flag

DF CapCtrl= DuctPresDischarge Fan

Capacity Control Flag

Remote DF Cap= 25%Remote Discharge Fan Capacity Set

Point

RF/EF Ctrl= TrackingReturn/Exhaust Fan


Rem RF/EF Cap= 25%

Remote Return/Exhaust Fan Capacity Set Point

Eng Units= English Engineering Units Control Flag

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discharge fan capacity to maintain the building static pressure at a building static pressure set point. If this parameter is set to “Position”, then the return or exhaust fan capacity is controlled to the Remote Return/Exhaust Fan Capacity Set Point. For detailed information regarding return or exhaust fan capacity control, refer to“Return Fan Capacity Control” on page 109 or “Energy Recovery” on page 105.Rem RF/EF CapThe the return or exhaust fan capacity is controlled to maintain the Remote Return/Exhaust Fan Capacity Set Point when the Return/Exhaust Fan Capacity Control Flag is set to “Position”. The Remote Return/Exhaust Fan Capacity Set Point is normally adjusted via a network signal but can also be adjusted via the keypad/display in the absence of a network tie to the parameter. For detailed information regarding return or exhaust fan capacity control, refer to“Return Fan Capacity Control” on page 109 or “Energy Recovery” on page 105.Eng UnitsThe Engineering Units Control Flag is used to select the system of engineering units used for displaying data on the keypad. If this parameter is set to “English”, the keypad data is displayed in inch-pound (I-P) units. If this parameter is set to “SI Canada”, the keypad data is displayed in the International System of Units (SI) used in Canada. If this parameter is set to “SI Europe”, the keypad data is displayed in the International System of Units (SI) used in Europe.

Control Timer Settings

Several MicroTech II internal control timers can be adjusted via the keypad/display Timer Settings menu. The following sections describe these timers.ServiceMany of the internal control timers can be temporarily sped up by using the Fast Service Timer. When set to a time value, the Fast Service Timer begins counting down. While this

parameter is counting down the following normal unit timers are set to the values below:

• Startup Initialization Timer — 20 seconds• Cooling Interstage Timer — 2 minutes• Heating Interstage Timer — 20 seconds

These timers return to their normal settings if the Fast Service Timer is manually set to 0 or when it counts down to 0.

Caution: This fast timers feature is meant to be used only by a knowledgeable service technician to facili-tate testing the unit.

RecirculateThe Recirculate State Timer defines the duration of the Recirc operating state applicable on units with return air (100% OA units have no Recirc operating state). Whenever a unit with return air is started or restarted, it always transitions through a “start sequence” which includes the Startup, followed by the Recirc operating state. During the Recirc operating state, the unit fans run while the outdoor air dampers remain closed. Heating and cooling operation are disabled during the Recirc operating state to allow the “system” air temperature conditions to equalize before temperature control begins. Once in the Recirc operating state, the unit remains there until the Recirculate State Timer expires. Low DATThe Low Discharge Temperature Ignore Timer sets the duration of a time period upon unit start up during which the Lo Disch Tmp fault is ignored. This may be particularly important in colder climates when a unit has been off for a significant time period during which the unit, including the discharge air temperature sensor, has become very cold. This time period allows the unit to run long enough to warm the discharge sensor above the alarm limit, preventing nuisance unit alarm shutdown. For detailed information regarding the Lo Disch Tmp fault refer to “Alarm Control” on page 115.Max MWUThe Maximum Morning Warm-up Timer sets a maximum duration for the MWU operating state applicable on units with return air (100% OA units have no MWU operating state). Whenever a unit with return air leaves the Recirc operating state, it enters the MWU operating state if the Ctrl Temp= parameter value is cold. The unit remains in the MWU operating state until either the Ctrl Temp= parameter value warms up or until the Maximum Morning Warm-up Timer expires. For detailed information regarding MWU operation, refer to “Heating: One Stage” on page 93, “Heating: Multistage” on page 94, or “Heating: Modulating” on page 96, as applicable.Tnt OvrdThe Tenant Override Time Increment sets the time period for which the unit operates each time the tenant override button on the optional space temperature sensor is pressed or the



Menu Name Item Name

Timer Settings

Service= 0 min Fast Service Timer

Recirculate= 3 min Recirculate State Timer

Low DAT= 3 minLow Discharge

Temperature Ignore Timer

Max MWU= 90 min Maximum Morning Warm-up Timer

Tnt Ovrd= 120 min Bypass Time Increment

Start Init= 120 min Startup Initialization Timer

Post Heat= 0 min Post Heat Timer

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Occ Mode= parameter is set to “Tnt Ovrd.” The Tnt Ovrd= parameter in the Occupancy menu is set or reset to this value when the tenant override button is pressed or the Occ Mode= parameter is set to “Tnt Ovrd.” The unit then operates until the Tnt Ovrd= parameter counts down to 0. For detailed information regarding bypass operation, refer to “Tenant Override” on page 55. Start InitThe Startup Initialization Timer defines the duration of the Startup operating state. When a unit is started or restarted, it always transitions through a “start sequence” that begins with the Startup operating state. During the Startup operating state, the unit fans remain off and heating and cooling are disabled. On units equipped with return air, the outdoor air damper actuator is driven closed. On units equipped with 100% outdoor air hoods, the outdoor air dampers are driven fully open. Discharge and return fan inlet vane actuators (if present) are driven to a 17% minimum startup position. Refer to “Operating States and Sequences” on page 70.Post HeatThe Post Heat Timer sets the duration of the “post heat” function available on VAV units. When a VAV unit changes from heating to cooling operation, it may be necessary to drive the unit airflow to a minimum position before allowing the VAV boxes to change to their cooling mode of operation. In some cases if this is not done, nuisance Duct Hi Limit fault shutdown may result. This can be accomplished by setting Post Heat Timer to a non-zero value in conjunction with utilizing the VAV Box Output signal (MCB-BO12). For detailed information regarding “post heat” operation, refer to “Discharge Fan Capacity Control” on page 108. For detailed information regarding the VAV Box Output, refer to “VAV Box Output” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.

Manual Output Control

The Manual Control menu is a special service menu that can be used to control many of the outputs on the main control board (MCB) in a manual mode. This can be used to test the operation of the various devices controlled by the outputs. This is very useful in determining whether a problem is the result of a wiring problem or defective device rather than a problem within the main controller.Manual ControlThe Manual Control Mode Flag is used to turn the manual control mode of operation on and off. When this parameter is set to “No” the unit operates normally. When this parameter is set to “Yes” normal operation of the control outputs is overridden and the condition of each output is defined by setting the remaining items within the Manual Control menu. All alarms are inactive when the Manual Control Mode Flag is set to “Yes” except the Duct Hi Limit fault. If the Duct Hi Limit fault occurs while the Manual Control Mode Flag is set to “Yes”, the unit is shut off on the fault, the Manual Control Mode Flag reverts to “No”, and the Ctrl Mode= parameter in the System menu reverts to “Off.” This means the unit remains off until the Ctrl Mode= parameter is



Menu Name Item Name

Manual Control

Manual Control = No Manual Control Mode Flag

Discharge Fan = Off Manual Discharge Fan Control Flag

RF/EF Fan = OffManual

Return/Exhaust Fan Control Flag

Fan Operation = Off Manual Fan Operation Output Control Flag

Alarm = Normal Manual Remote Alarm Output Control Flag

OA Damper = Auto Manual OA Damper Control Flag

Mod Cooling = AutoManual Modulating

Cooling Valve Control Flag

Mod Heating = AutoManual Modulating

Heating Valve Control Flag

VAV Output = Heat Manual VAV Box Output Control Flag

Disch Vanes = AutoManual Discharge

Vane Actuator Control Flag

RF/EF Vanes = AutoManual

Return/Exhaust Vane Actuator Control Flag

Disch VFD = Auto Manual Discharge VFD Control Flag

RF/EF VFD = AutoManual

Return/Exhaust VFD Control Flag

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changed to something other than “Off.” Refer to “Auto/Manual Operation” on page 52.

Note: If the Calibrate Mode= parameter in the Unit Con-figuration menu is set to “Yes” while the Manual Control Mode Flag is set to “Yes”, the Manual Con-trol Mode Flag reverts to “No.”

Discharge FanThe Manual Discharge Fan Control Flag is used to manually turn the discharge air fan on and off. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “On” the discharge air fan is turned on. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Off” the discharge air fan is turned off.RF/EF FanThe Manual Return/Exhaust Fan Control Flag is used to manually turn the return or exhaust fan on and off. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “On” the return or exhaust fan is turned on. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Off” the return or exhaust fan is turned off.Fan OperationThe Manual Fan Operation Output Control Flag is used to manually turn the Fan Operation Output (MCB-BO3) on and off. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “On” the Fan Operation Output is turned on. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Off” the Fan Operation Output is turned off. For detailed information regarding the Fan Operation Output, refer to “Fan Operation Output” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.AlarmThe Manual Remote Alarm Output Control Flag is used to manually turn the Remote Alarm Output (MCB-BO4) on and off. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Normal” the Remote Alarm Output is turned on. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Alarm” the Remote Alarm Output is turned off. For detailed information regarding the Remote Alarm Output, refer to “Remote Alarm Output” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.OA DamperThe Manual OA Damper Control Flag is used to manually drive the outdoor air dampers open and closed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Open” the open outdoor damper output (MCB-BO6) is turned on and the outdoor air dampers stroke open continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Close” the close outdoor damper output (MCB-BO5) is turned on and the outdoor air dampers stroke closed continuously. When the Manual

Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the open and close outdoor damper outputs remain off and the outdoor air dampers remain at their current position.Mod CoolingThe Manual Modulating Cooling Valve Control Flag is used to manually drive the modulating cooling valve open and closed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Open” the open cooling valve output (MCB-BO8) is turned on and the cooling valve strokes open continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Close” the close cooling valve output (MCB-BO7) is turned on and the cooling valve strokes closed continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the open and close cooling valve outputs remain off and the cooling valve remains at its current position.Mod HeatingThe Manual Modulating Heating Valve Control Flag is used to manually drive the modulating heating valve open and closed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Open” the open heating valve output (MCB-BO10) is turned on and the heating valve strokes open continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Close” the close heating valve output (MCB-BO9) is turned on and the heating valve strokes closed continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the open and close heating valve outputs remain off and the heating valve remains at its current position.VAV OutputThe Manual VAV Box Output Control Flag is an adjustable item used to manually turn the VAV Box Output (MCB-BO12) on and off. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Cool” the VAV Box Output is turned on. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Heat” the VAV Box Output is turned off. For detailed information regarding the VAV Box Output, refer to “VAV Box Output” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.Disch VanesThe Manual Discharge Vane Actuator Control Flag is used to manually drive the discharge fan inlet vanes open and closed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Open” the open discharge inlet vanes output (MCB-BO14) is turned on and the vanes stroke open continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Close” the close discharge inlet vanes output (MCB-BO13) is turned on and the vanes stroke closed continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the open and close discharge inlet vanes outputs remain off and the vanes remain at their current position.

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RF/EF VanesThe Manual Return/Exhaust Vane Actuator Control Flag is used to manually drive the return air or exhaust fan inlet vanes open and closed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Open” the open return or exhaust inlet vanes output (MCB-BO16) is turned on and the vanes stroke open continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Close” the close return or exhaust inlet vanes output (MCB-BO15) is turned on and the vanes are stroked closed continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the open and close return or exhaust inlet vanes outputs remain off and the vanes remain at their current position.Disch VFDThe Manual Discharge VFD Control Flag is used to manually increase and decrease the discharge air fan VFD speed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Faster” the increase discharge fan VFD speed output (MCB-BO14) is turned on and the VFD speed increases continuously. When Manual Control Mode Flag is set to “Yes” and this parameter is set to

“Slower” the decrease discharge fan VFD speed output (MCB-BO13) is turned on and the VFD speed decreases continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the increase and decrease discharge fan VFD speed outputs remain off and the VFD remains at its current position.RF/EF VFDThe Manual Return/Exhaust VFD Control Flag is used to manually increase and decrease the return air or exhaust fan VFD speed. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Faster” the increase return or exhaust fan VFD speed output (MCB-BO-16) is turned on and the VFD speed increases continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Slower” the decrease return or exhaust fan VFD speed output (MCB-BO15) is turned on and the VFD speed decreases continuously. When the Manual Control Mode Flag is set to “Yes” and this parameter is set to “Auto” the increase and decrease return or exhaust fan VFD speed outputs remain off and the VFD remains at its current position.

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Description of OperationThe following sections describe how the various discharge air temperature control unit processes function to maintain temperature, ventilation and pressure control. The “Operating States and Sequences” section provides an overall description of unit operation. The subsequent sections provide detailed descriptions of the various control processes and how the related set points and parameters affect them. The related set points and parameters are listed at the beginning of each applicable sub-section. The default keypad programmable values are shown in italic letters.

Note: Not all the features covered in this section apply to all units depending on the specific unit options. The applicable items should be read and understood before making set point or control parameter changes.

Operating States and SequencesAbout Operating StatesOperating states define the current overall status of the rooftop unit. The operating state can be displayed and the unit operating condition can be quickly determined by viewing the UnitStatus= parameter in the System menu. Each operating state summarizes the following information:

• Discharge and return/exhaust fan status• Outdoor air damper status• Discharge airflow capacity• Return/exhaust airflow capacity• Heating system status• Cooling system status• Fan Operation Output status (MCB-BO3)• VAV Box Output status (MCB-BO12)

Table 27 shows the all the normal operating states and the status information they summarize.

Table 27: Operating States

Operating State

Discharge/ Return Fans

Exhaust Fan(s)

OA Dampers

Discharge Airflow

Capacity

Return Airflow

Capacity

Exhaust Airflow

CapacityHeat

EnabledMechanical

Cooling Enabled

Fan Output (MCB-BO3)

VAV Box Output

(MCB-BO12)

Off Off Off Closed 0% 0% 0% No No Opena Closed or Openb

Startup Off Off Closedg 0% 0% 0% No No Closed Open

Recirc On Off Closed Modulating Modulating 0% No No Closed Open

Fan Only On Off Minimum Modulatingc Modulatingc 0% No No ClosedClosed or

Opend

Econo On Cycling Modulating Modulating Modulating Modulating No No Closed Closed

Cooling On CyclingMinimum or

Opene Modulating Modulating Modulating No Yes Closed Closed

MWU On Off Closed Modulating Modulating 0% Yes No Closed OpenHeating On Off Minimum Modulating Modulating 0% Yes No Closed Open

Min DAT On Off Minimum Modulatingc Modulatingc 0% Yes No ClosedClosed or

Opend

UnocEcon On Cycling Modulating Modulating Modulating Modulating No No Closed Open

UnocClg On CyclingClosed or

Openf Modulating Modulating Modulating No Yes Closed Open

UnocHtg On Off Closed Modulating Modulating 0% Yes No Closed Open

a. If the DF CapCtrl= parameter in the Unit Configuration menu is set to “DuctPress”, the output turns off (open) 30 seconds after the unit airflow switch (PC7) opens. In this case if PC7 is closed, the Fan Operation Output remains on (closed). If the DF CapCtrl= parameter in the Unit Configuration menu is set to “Position”, the output turns off (open) 3 minutes after the unit enters the Off state. In this case the output remains off until the unit is re-started.

b. The VAV Box Output is normally in the closed (cool) position in this operating state unless airflow is detected. If airflow is detected, the VAV Box Output switches to the open (heat) position

c. The discharge and return airflow is driven to minimum for an adjustable post heat time period when the Post Heat= parameter is set to a non-zero value when the unit enters the Fan Only or Min DAT operating state from either the Recirc or any heating operating state. Refer to “Post Heat” in the “Discharge Fan Airflow Control” section of this man-ual.

d. The VAV Box Output is normally in the closed (cool) position in this operating state. However, if the VAV Box Output is in the open (heat) position upon entering this operating state, it remains in the open (heat) position for a time period defined by the Post Heat= parameter or unit the discharge inlet vane position drops below 17% (VFD speed below 25%).

e. When the OA Ambient= parameter indicates “Low”, the economizer outdoor air dampers is fully open; when the OA Ambient= parameter indicates “High”, the economizer outdoor air dampers are at Eff Min OA Pos= value.

f. When the OA Ambient= parameter indicates “Low”, the outdoor air dampers are fully open; when the OA Ambient= parameter indicates “High”, the outdoor air dampers are fully closed.

g. Except on 100% OA units. Dampers are driven fully open during the startup operating state in this case.

70 OM-137-2

Operating State DescriptionsThe following sections describe each of the unit operating states.OffThere are five different Off operating states. In any of the Off operating states the unit is shut down. The fans are off, the outdoor air dampers are closed, any fan inlet vanes or VFD are driven to 0%. Cooling and heating are disabled. The Fan Operation Output (MCB-BO3) is open and the VAV Box Output (MCB-BO12) is in the closed (cool) position unless airflow is detected by the PC7 airflow switch, in which case it is in the open (heat) position.

Note: If the DF CapCtrl= parameter in the Unit Configu-ration menu is set to “DuctPress”, the Fan Opera-tion Output turns off 30 seconds after the unit airflow switch (PC7) opens. In this case if PC7 is closed, the Fan Operation Output remains closed. If the DF CapCtrl= parameter in the Unit Configura-tion menu is set to “Position”, the Fan Operation Output turns off three minutes after the unit enters the Off state. In this case the Fan Operation Output remains off until the unit is re-started.

The five different Off operating states are described in the following sections:

Off Unoc . Generally, the unit operating state is Off Unoc when it is being scheduled on and off by a time clock function and the time schedule indicates an unoccupied period. Specifically, the operating state is Off Unoc when the Occupancy= parameter indicates “Unocc” and none of the unoccupied unit operation functions are active. For details regarding the Occupancy= parameter refer to “Occupancy” on page 53. For details regarding unoccupied unit operation functions refer to “Unoccupied Control” on page 114.

Off Net . The unit operating state is Off Net when the Appl Mode= parameter is set to “Off” via a network signal and the Ctrl Mode= parameter is set to “Auto.” For detailed information regarding the Appl Mode= and Ctrl Mode= parameter, refer to “Auto/Manual Operation” on page 52.The unit operating state is also Off Net when the Emerg Override= parameter in the Occupancy menu is set to “Off.” Refer to “Emergency Override” on page 56.

Off Sw. The unit operating state is Off Sw when a field supplied and installed switch across terminals 101 and 104 on the unit field terminal block (TB2) is in the on or closed position (binary input MCB-BI2 on). Refer to “Manual Unit Enable/Disable” in IM 696, MicroTech II Applied Rooftop Unit Controller.

Off Alm. The unit operating state is Off Alm when an active alarm of the “fault” type has a unit shut down. Refer to “Alarm Monitoring” on page 59 for a description of “fault” alarms.

Off Man. The unit operating state is Off Man when the Ctrl Mode= parameter is set to “Off.” For detailed information regarding the Ctrl Mode= parameter, refer to “Ctrl Mode” on page 52.Startup When a unit is commanded to start it always enters the Startup operating state from the Off operating state. The unit remains in the Startup operating state for an adjustable time period defined by the Start Init= parameter in the Timer Settings menu (default value is 180 seconds) before entering the Recirc operating state. During the Startup operating state the unit is prepared for startup. The fans remain off, the outdoor air dampers are driven closed, any fan inlet vanes are driven to a fixed 17% minimum position (VFD remains at 0% speed). Cooling and heating remain disabled. The Fan Operation Output (MCB-BO3) is closed and the VAV Box Output (MCB-BO12) is in the open (heat) position.For more information regarding the Startup operating state, refer to “Startup Control” on page 74.RecircUnits with return air always enter the Recirc operating state after the completion of the Startup operating state. In the Recirc operating state fans are started and operate while the outdoor air dampers remain closed. This allows temperature conditions throughout the unit and space to equalize before temperature control begins. Cooling and heating remain disabled. The Fan Operation Output (MCB-BO3) is closed, the VAV Box Output (MCB-BO12) is in the open (heat) position and in VAV applications normal duct static pressure or position control is maintained. The Recirc operating state is particularly important for applications in which the return air temperature sensor is being used for heat/cool changeover control. The unit remains in the Recirc operating state until the Recirculate State Timer expires. This timer is adjustable from 2 to 60 minutes with the Recirculate= parameter in the Timer Settings menu.

Note: 100% outdoor air units do not transition through the Recirc operating state.

For more information regarding the Recirc operating state, refer to “Startup Control” on page 74.Fan OnlyThe unit enters the Fan Only operating state during occupied operation when cooling and heating are either not required based unit on the heat/cool changeover function or are disabled. During the Fan Only operating state, the outdoor air dampers are either 100% open on a 100% outdoor air unit or are controlled to the Eff Min OA Pos= parameter in the OA Damper menu. Cooling and heating operation is disabled. The Fan Operation Output (MCB-BO3) is closed, the VAV Box Output (MCB-BO12) is normally in the close (cool) position and in VAV applications normal duct static pressure or position control is maintained.

OM-137-2 71

Note: The VAV Box Output can be in the open (heat) position during the Fan Only operating state when “post heat” operation is active. For detailed infor-mation regarding “post heat” operation, refer to “Post Heat Operation” on page 109.

EconoThe unit enters the Econo operating state when cooling is required during occupied operation when economizer operation is enabled. During the Econo operating state, mechanical cooling and heating are disabled. The outdoor and return air dampers are modulated to maintain the discharge air temperature at the Eff Clg Spt= parameter in the Discharge Cooling menu. The Fan Operation Output (MCB-BO3) is closed, the VAV Box Output (MCB-BO12) is in the closed (cool) position and in VAV applications normal duct static pressure or position control is maintained.

Note: 100% outdoor air units do not transition through the Econo operating state.

For detailed information regarding economizer operation, refer to “Economizer” on page 78.CoolingThe unit enters the Cooling operating state during occupied operation when cooling is required and the economizer is either disabled, not present, or already fully opened. During the Cooling operating state, the outdoor air dampers are fully open if the unit is a 100% outdoor air unit or if economizer operation is enabled. The outdoor air dampers are controlled to the Eff Min OA Pos= parameter if economizer operation is disabled or not present. Mechanical cooling is supplied as required to maintain the discharge air temperature at the Eff Clg Spt= in the Discharge Cooling menu. The Fan Operation Output (MCB-BO3) is closed, the VAV Box Output (MCB-BO12) is in the closed (cool) position and in VAV applications normal duct static pressure or position control is maintained. Heating is disabled.For detailed information regarding the cooling operation, refer to “Cooling: Multistage” on page 82 or “Cooling: Modulating” on page 92 as applicable.MWUWhen the unit transitions from unoccupied to occupied operation and heating is required to warm the Ctrl Temp= parameter up to the Eff Htg Spt= setting in the Zone Heating menu, the unit enters the MWU (Morning Warm-up) operating state after the Startup and Recirc operating states are complete. The MWU operating state is similar to the Heating operating state except that the outdoor air dampers are held closed rather than controlled to the Eff Min OA Pos= parameter. Once entering the MWU operating state, the unit remains there until either the Ctrl Temp= parameter warms up to the Eff Htg Spt= setting in the Zone Heating menu or until a maximum morning warm-up time period expires. This time period is defined by the Max MWU= parameter in the Timer Settings menu. The Fan Operation Output (MCB-BO3) is closed, the VAV Box Output (MCB-

BO12) is in the open (heat) position and in VAV applications normal duct static pressure or position control is maintained. Cooling is disabled.

Note: 100% outdoor air units do not transition through the MWU operating state.

For detailed information regarding morning warm-up heating operation, refer to “Heating: One Stage” on page 93, “Heating: Multistage” on page 94, or “Heating: Modulating” on page 96 as applicable.HeatingThe unit enters the Heating operating state when heating is required during occupied operation. During the Heating operating state, the outdoor air dampers are either 100% open if the unit is a 100% outdoor air unit or controlled to the Eff Min OA Pos= parameter. Cooling is disabled. The Fan Operation Output (MCB-BO3) is closed, the VAV Box Output (MCB-BO12) is in the open (heat) position and in VAV applications normal duct static pressure or position control is maintained. For detailed information regarding heating operation, refer to “Heating: One Stage” on page 93, “Heating: Multistage” on page 94, or “Heating: Modulating” on page 96 as applicable.Min DATThe unit enters the Min DAT operating state during occupied operation when neither cooling nor heating is required based on the unit heat/cool changeover function but the discharge air temperature falls below the Eff Clg Spt= parameter in the Discharge Cooling menu. The Min DAT operating state prevents cold discharge air temperatures during what would normally be the Fan Only operating state. During the Min DAT operating state, the outdoor air dampers are either 100% open if the unit is a 100% outdoor air unit or are controlled to the Eff Min OA Pos= parameter. Cooling is disabled. The Fan Operation Output (MCB-BO3) is closed, the VAV Box Output (MCB-BO12) is normally in the closed (cool) position and in VAV applications normal duct static pressure or position control is maintained.

Note: The VAV Box Output can be in the open (heat) position during the MinDAT operating state when “post heat” operation is active. For detailed infor-mation regarding “post heat” operation, refer to “Post Heat Operation” on page 109.

Note: The Min DAT operating state is available on units with modulating or multistage heating only.

For detailed information regarding the Min DAT operating state, refer to “Discharge Air Low Limit Control” on page 96 (multistage heat) or “Discharge Air Low Limit Control” on page 99 (modulating heat) as applicable.UnocEconThe unit enters the UnocEcon operating state if the outdoor air is suitable for free cooling when “purge” or unoccupied

72 OM-137-2

cooling (night setup) operation is required. During the UnocEcon operating state, the outdoor air dampers are modulated to maintain the discharge air temperature at the Eff Clg Spt= parameter in the Discharge Cooling menu. Mechanical cooling is disabled. The Fan Operation Output (MCB-BO3) is closed, the VAV Box Output (MCB-BO12) is in the open (heat) position to allow VAV boxes to open fully and in VAV applications normal duct static pressure or position control is maintained. Heating is disabled.

Note: 100% outdoor air units do not transition through the UnocEcon operating state

For detailed information regarding unoccupied economizer operation, refer to “Unoccupied Cooling (Night Setup)” on page 114 and “Purge” on page 115.UnocClgThe unit enters the UnocClg operating state when unoccupied cooling (night setup) operation is required and the economizer is either disabled, not present, or already fully opened. During the UnocClg operating state, the outdoor air dampers are fully open if the unit is a 100% outdoor air unit or if economizer operation is enabled. The outdoor air dampers are at 0% if economizer operation is disabled or not present. The Fan Operation Output (MCB-BO3) is closed, the VAV Box Output (MCB-BO12) is in the open (heat) position to allow VAV boxes to open fully and in VAV applications normal duct static pressure or position control is maintained. Heating is disabled.For detailed information regarding the unoccupied cooling operation, refer to “Unoccupied Cooling (Night Setup)” on page 114.UnocHtgThe unit enters the UnocHtg operating state when unoccupied heating (night setback) operation is required. During the UnocHtg operating state, the outdoor air dampers are closed. The Fan Operation Output (MCB-BO3) is closed, the VAV Box Output (MCB-BO12) is in the open (heat) position to allow VAV boxes to open fully and in VAV applications normal duct static pressure or position control is maintained. Cooling is disabled.For detailed information regarding the unoccupied heating operation, refer to “Unoccupied Heating (Night Setback)” on page 114.UnocFanOThe UnocFanO operating state is not a “typical” operating state. If night set back operation is activated while the unit

heating is disabled or if the unit is not equipped with heating equipment, the unit with enter the UnocFanO operating state in lieu of the UnocHtg operating state. Unit operation is the same as describe for the Fan Only operating state except that the outdoor air dampers are controlled as in the UnocHtg operating state.The unit will also enter the UnocFanO operating state if cooling or heating are disable while in the UnocEcon, UnocClg or UnocHtg operating states. If entering the UnocFanO operating state from the UnocEcon or UnocClg operating state, the outdoor dampers are control as describe for the UnocClg operating state.For detailed information regarding the unoccupied heating or cooling operation, refer to “Unoccupied Control” on page 114.BalanceThe unit enters the Balance operating state when the Fan Balance= parameter in the Fan Balance menu is set to “On”. The function is used to set the discharge fan and return fan capacity tracking relationship on a VAV unit when the DF CapCtrl= parameter in the Unit Configuration menu is set to “Tracking”. Heating and cooling operation are disabled during the Balance operating state.

Note: The Fan Balance= parameter cannot be set to “On” when the unit is in the Off, Startup or Recirc operat-ing states.

For detailed information regarding balance operation refer to “Automatic Discharge/Return Fan Balancing Procedure” on page 110.Man CtrlThe unit enters the Man Ctrl operating state when the Manual Control= parameter in the Manual Control menu is set to “Yes”. During manual operation, all the unit control functions are disabled and the main control board (MCB) outputs can be turned on and off manually by setting the parameters contained in the Manual Control menu.For detailed information regarding manual unit control, refer to “Manual Output Control” on page 67.

Operating State Sequence ChartOperating states and the transitions between them help to describe the unit sequences of operation. Figure 7 shows all of the operating state transitions that can occur as a result of normal control. Depending on the unit options, some operating states may not apply.

OM-137-2 73

Figure 7: Operating State Sequence Chart

Startup ControlA rooftop unit can startup and run for a variety of reasons. Examples are the internal time schedule function, an external time clock signal, a tenant override signal or the unoccupied heating (night setback) and cooling (night setup and purge) functions. Regardless of the reason it is started, the unit always transitions through a “controlled” startup sequence before allowing temperature control to begin.

Before Startup

When the controller receives a startup command, its operating state changes from the Off to Startup operating state. During the Startup operating state, the Fan Operation Output (MCB-BO3) is closed to indicate that the fans are about to start. On VAV units with inlet vanes, the discharge and return fan vanes are driven open to the non-adjustable Minimum Inlet Vane Position Limit. This limit is 17% and is not adjustable. The Minimum Inlet Vane Position Limit assures that the fans do not start with a completely blocked airflow path. On VAV units with VFDs, the VFDs remain at

0% speed. The unit remains in the Startup operating state until the Startup Initialization Timer expires.

Note: On 100% OA units equipped with gas heat, the Startup period may last longer than the period defined by the Startup Initialization Timer if heat is required at unit startup. For a description of this special 100% OA gas heat startup sequence, refer to “Gas Heat” on page 97.

Caution: The Startup Initialization Timer should be set so that the Startup operating state lasts long enough to allow any field-supplied equipment (such as isolation damper sets) controlled by the Fan Operation Output (MCB-BO3) to prepare for fan operation.

Fan Startup

Return Air Units The unit enters the Recirc operating state after leaving the Startup operating state. During the Recirc operating state, the

Any State OFF

Startup

Recirc

UnocClg

UnocEcon

Cooling

Economizer

Fan Only

Min DAT

Heating

MWU

UnocHtg



Menu Name Item Name

- - Minimum Inlet Vane Position Limit

Timer Settings Start Init = 3 min Startup Initialization Timer Table 29: Programmable Parameters


Menu Name Item Name

- - Fan Delay Timer

- - Airflow Check Timer

Timer Settings Recirculate= 3 min Recirculate State Timer

74 OM-137-2

fans are stated and operated with the outdoor air dampers closed to allow temperature conditions throughout the unit and space to equalize before temperature control begins. Cooling and heating remain disabled. The VAV Box Output (MCB-BO12) is in the open (heat) position to allow the VAV boxes to open fully to facilitate efficient system air circulation.As soon as the unit leaves the Startup operating state, the discharge fan starts and the following three timers are reset and start timing down: (1) the Fan Delay Timer, (2) the Airflow Check Timer, and (3) the Recirculate State Timer.When the Fan Delay Timer expires, the return fan is started (if present). The Fan Delay Timer value is a fixed four seconds. Once both fans start, the discharge fan capacity is modulated to maintain the duct static pressure or position set point (VAV units). The return fan capacity (if variable) is modulated to either track the discharge capacity, maintain the building static pressure or position set point as applicable. For detailed information regarding return fan capacity control, refer to “Return Fan Capacity Control” on page 109.The Fan Fail fault and the Fan Retry problem which indicate loss of airflow are prevented from occurring after leaving the Startup operating state until the Airflow Check Timer expires. The Airflow Check Timer value is a fixed two minutes. This is to prevent nuisance unit airflow sensing related faults (particularly on VAV units) while the airflow is increasing.Once in the Recirc operating state, the unit remains there until the Recirculate State Timer and Airflow Check Timer expire. After the unit leaves the Recirc operating state, the operating state entered is a function of the current occupied/unoccupied as well as the current temperature conditions. The Heat/Cool Changeover section describes the heating/cooling changeover function, which dictates whether the unit enters a heating, cooling or the Fan Only operating state. 100% Outdoor Air UnitsIf the unit is equipped with a 100% outdoor air hood, the Recirc operating state is bypassed and the fans are started as the unit directly enters either a heating or the Fan Only operating state after leaving the Startup operating state.As soon as the unit leaves the Startup operating state, the discharge fan starts and the Airflow Check Timer is reset and starts timing down. This timer value is a fixed two minutes.Once the discharge fan starts, the discharge fan capacity is modulated to maintain the duct static pressure or position set point (VAV units). The Fan Fail fault and the Fan Retry problem which indicate loss of airflow are prevented from occurring after leaving the Startup operating state until the Airflow Check Timer expires. This is to prevent nuisance unit airflow sensing related faults (particularly on VAV units) while the airflow is increasing.

After the unit leaves the Startup operating state, the operating state entered is a function of the current occupied/unoccupied as well as the current temperature conditions. The following section describes the heating/cooling changeover function, which dictates whether the unit enters a heating, cooling or the Fan Only operating state.

Note: While the Airflow Check Timer is timing down and, therefore, while the Fan Fail fault and the Fan Retry problem alarms are being ignored, the unit will not be allowed to enter a cooling operating state.

Heat/Cool ChangeoverIn general, a unit configured for discharge air temperature control either operates to deliver the cooling discharge temperature set point using economizer and/or mechanical cooling or the heating discharge air temperature set point using the heating equipment. Cooling and heating never operate simultaneously. The following sections describe the unit heat/cool changeover function.

Temperature Control

Control TemperatureThe “Control Temperature” is defined as the unit temperature input used to make the heat/cool changeover decision. This determines whether or not cooling or heating is enabled. Normally the return air temperature input is used as the “Control Temperature.” Alternatively, if the unit is equipped with modulating or multistage heat, the outdoor air temperature input can be selected as the “Control Temperature”. If an optional space temperature sensor is installed, the space temperature input may be selected as the



Menu Name Item Name

Zone Cooling

CntlTemp Src= Return Control Temperature Source

Eff Clg Spt= ____ °F Effective Cooling Enable Set Point

Occ Clg Spt= 75.0 ºF Cooling Enable Set Point

Clg Deadband= 1.0 ºF Cooling Enable Dead Band

Zone Heating


Eff Htg Spt= ____ °F Effective Heating Enable Set Point

Occ Htg Spt= 70.0 ºF Heating Enable Set Point

Htg Deadband= 1.0 ºF Heating Enable Dead Band

OM-137-2 75

“Control Temperature.” The current value of the “Control Temperature” can be displayed be viewing the Ctrl Temp= parameter in the Temperatures menu.When the Control Temperature Source is set to “Return”, the unit return air temperature sensor acts as the “Control Temperature.” When the Control Temperature Source is set to “Space”, the unit space air temperature sensor acts as the “Control Temperature.” When the Control Temperature Source is set to “OAT”, the outdoor air temperature sensor acts as the “Control Temperature.” For most applications, the return air temperature sensor, when present, is the best “Control Temperature.”Once enabled by the “Control Temperature” cooling or heating capacity control operates as described in “Economizer” on page 78, “Cooling: Multistage” on page 82, “Cooling: Modulating” on page 92, “Heating: One Stage” on page 93, “Heating: Multistage” on page 94, or “Heating: Modulating” on page 96 as applicable. The following sections describe in detail how the “Control Temperature” enables cooling and heating operation.

Note: Although enabled based on the “Control Tempera-ture”, cooling or heating operation can be disabled for other reasons. Refer to “Clg Status” on page 50 and “Htg Status” on page 51.

Set Points and Dead BandsIn determining whether heating or cooling operation is enabled, the controller compares the “Control Temperature” input with separate cooling and heating enable set points. When the “Control Temperature” is greater than the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band, cooling operation is enabled. When the “Control Temperature” is below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band, heating operation is enabled. Separate cooling and heating enable dead bands assure that the unit does not cycle rapidly between cooling and heating.When the “Control Temperature” is between the two effective set points and dead bands, cooling and heating operation are disabled and the unit runs in the Fan Only operating state. If the unit is equipped with modulating or multistage heat, the unit can operate the heat in this case based on a discharge temperature low limit function if the discharge air temperature gets too cold. Refer to “Discharge

Air Low Limit Control” on page 96 (multistage heat) or “Discharge Air Low Limit Control” on page 99 (modulating heat) as applicable.The Effective Cooling Enable Set Point and Effective Heating Enable Set Point are not adjustable from the keypad. They are set equal to the Cooling Enable Set Point and Heating Enable Set Point respectively. This means the Effective Cooling Enable Set Point and the Effective Heating Enable Set Point parameters must be adjusted indirectly by changing the Cooling Enable Set Point and Heating Enable Set Point.Cooling and heating can never be simultaneously enabled because the controller prevents the set points and dead bands from being set so that the Cooling Enable Dead Band and Heating Enable Dead Band overlap. In doing this, the controller always gives the Effective Cooling Enable Set Point the highest priority. Regardless of whether the cooling set point is lowered, the heating set point is raised or either of the dead bands are raised, the controller automatically lowers the Effective Heating Set Point enough to prevent the dead bands from overlapping.Illustrative Heat/Cool Changeover SequenceThe following is an illustration of the heat/cool changeover function. Refer to Figure 8 on page 77.When the “Control Temperature” rises above the Effective Cooling Enable Set Point by more than half of the Cooling Enable Dead Band (Point A), cooling operation is enabled (economizer and mechanical). Cooling operation then remains enabled until the “Control Temperature” begins to drop and falls below the Effective Cooling Enable Set Point by more than half of the Cooling Enable Dead Band (Point B), at which point cooling operation is disabled (economizer and mechanical). The unit enters the Fan Only or MinDAT operating state. When the “Control Temperature” drops below the Effective Heating Enable Set Point by more than half of the Heating Enable Dead Band (Point C), heating operation is enabled. Heating operation then remains enabled until the “Control Temperature” begins to rise and rises above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band (Point D), at which point the unit returns to the Fan Only or MinDAT operating state.

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Figure 8: Illustrative Heat/Cool Changeover Operating Sequence

0-30% Outdoor Air Damper ControlMinimum Ventilation Control

Whenever the unit is in the Fan Only, Cooling, Heating or Min DAT operating state, the outdoor air dampers are prevented from closing below the Minimum Outdoor Damper Position Set Point. During the Off, Startup, Recirc, and MWU operating states, the outdoor air dampers are driven continuously to 0%.Unoccupied OperationWhenever the unit is operating in the unoccupied operating states UnocClg or UnocHtg, the outdoor air dampers are driven continuously to 0%.

No Minimum OA ResetWith the 0-30% OA Damper arrangement, the Minimum Outdoor Damper Position Reset Flag can only be set to “None”. The dampers are always control to the Minimum Outdoor Damper Position Set Point except as noted in the previous section when they are continuously driven to 0%.Network OA ResetWhen the Minimum Outdoor Damper Position Reset Flag is set to “None”, the Minimum Outdoor Damper Position Set Point can be reset between 0-30% via a network signal.

100% Outdoor Air Damper ControlWhen a unit is equipped with a 100% outdoor air hood, the outdoor air dampers are driven open continuously whenever the unit enters the Startup operating state. If they are not open (above 50%) at the end of the Startup operating state or any time afterward while the fans are running, the unit is shutdown on the OA Dmpr Stuck fault. When the unit is shut down, the dampers remain open for 30 seconds after the unit airflow switch opens up indicating loss of airflow.

Note: The dampers remain open in the event that the air-flow switch does not open after the fans are shut down.

A

B

C

D

Cooling Enable Dead Band

FanOnly (or Min DAT)

Heating Enable Dead Band

Cooling Enabled

Heating Enabled

Time

Con

trol T

empe

ratu

reEffective CoolingEnable Set Point

Effective HeatingEnable Set Point



Menu Name Item Name

OA Damper

MinOA Type= NoneMinimum Outdoor Damper Position

Reset Flag

MinOA Pos= 10%Minimum Outdoor

Damper Position Set Point

OM-137-2 77

EconomizerTemperature Control

Entering Econo Operating StateIf a unit is equipped with a 0-100% modulating economizer, and the outdoor air is suitable for free cooling as described in “Economizer Changeover Method” on page 79, the unit attempts to satisfy the cooling load by using outdoor air before using mechanical cooling. In this case, when the Ctrl Temp= parameter is above the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band and the Disch Air= parameter is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band, the controller enters the Econo state.When the unit is in the Econo operating state, the outdoor air dampers are modulated as required to maintain the Effective Discharge Cooling Set Point.

Note: Unless it is reset via one of the discharge air set point reset methods described in “Cooling Dis-charge Set Point Reset” on page 100, the Effective Discharge Cooling Set Point is set by the controller equal to the Discharge Cooling Set Point.

The controller uses three PID control loop parameters to modulate the dampers as the discharge air temperature changes. Theses are the Economizer Cooling Proportional Band, Economizer Cooling Integral Time and Economizer Cooling Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.

Economizer to Cooling Operating StateThe transition from the Econo to Cooling operating state occurs when the economizer is unable to satisfy the cooling load and mechanical cooling is available. Normally, this occurs when the OA Damper Pos= parameter indicates more than 95% open and the discharge air temperature is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band for longer than the Cooling Interstage Timer.To allow for the transition from the Econo to Cooling operating state in the event the outdoor air dampers get stuck or there is a problem with the damper actuator feedback circuit and the OA Damper Pos= parameter does not reach 95%, the controller continually estimates the position of the dampers. This estimate is based on the accumulative damper drive open versus drive close time compared to the nominal stroke of the actuator. If the controller position estimate reaches 100% open and the discharge air temperature is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band for longer than the Cooling Interstage Timer, the unit makes the transition from the Econo to Cooling operating state regardless of the current OA Damper Pos= parameter indication.If the OA Ambient= value changes from “Low” to “High” at any time while the unit is in the Econo operating state, the transition from the Econo to Cooling operating state occurs if mechanical cooling is enabled. The outdoor air dampers are driven to the Effective Minimum Outdoor Damper Position Set Point (refer to “Minimum Ventilation Control” on page 79).Whenever a unit is in the Cooling operating state and the OA Ambient= parameter indicates “Low”, the outdoor air dampers are driven continuously open. They remain there as long as the OA Ambient= parameter indicates “Low”. If mechanical cooling is no longer necessary, the unit leaves the Cooling and re-enters the Econo operating state and damper modulation resumes.

Note: The unit remains in the Cooling operating state for at least one Cooling Interstage Timer period.

Econo to Fan Only Operating StateThe unit will leave the Econo operating state and enter the Fan Only operating state when the Ctrl Temp= value falls below the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band. The unit will also leave the Econo operating state and enter the Fan Only operating state if the OA Damper Pos= parameter indicates that the outdoor dampers have been at the Effective Minimum Outdoor Damper Position Set Point for one Cooling Interstage Timer period and the Disch Air= parameter is below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band.The unit will also leave the Econo operating state and enter the Fan Only operating state if all cooling is disabled for any reason.



Menu Name Item Name

Zone CoolingEff Clg Spt= ___ ºF Effective Cooling

Enable Set Point


Discharge CoolingEff Clg Spt= ___ ºF Effective Discharge

Cooling Set Point

Clg Db= 1.0 ºF Discharge Cooling Dead Band

Compressor Setup Stage Timer= 5 min Cooling Interstage Timer

Economizer Setup

Clg Propbd= 30.0 ºF Economizer Cooling Proportional Band

Clg IntTime= 100 sec Economizer Cooling Integral Time

Clg Period= 30 sec Economizer Cooling Period

78 OM-137-2

Economizer Changeover Method

There are three methods of determining whether or not the outdoor air is suitable for free cooling. Two of them sense enthalpy (dry bulb temperature and humidity) and one senses outdoor air dry bulb temperature only.Enthalpy ChangeoverThe two optional enthalpy changeover methods use external control devices. One device compares the outdoor air enthalpy with a set point; the other compares the outdoor air enthalpy with the return air enthalpy. All units with economizers are at least equipped with the outdoor air enthalpy version. The comparative version is optional. In either case a binary input (MCB-BI11) is delivered to the controller indicating whether or not outdoor air is suitable for free cooling. When the outdoor air is suitable for free cooling (MCB-BI11 on), the OA Ambient= parameter indicates “Low” and the economizer operates as described in “Economizer” on page 78. When the outdoor air is not suitable for free cooling (MCB-BI11 off), the OA Ambient= parameter indicates “High” and economizer operation is disabled.To use either of these enthalpy methods, the Economizer Changeover Flag must be set to “Enthalpy.” In this case, the Economizer Changeover Set Point is ignored. For detailed information regarding the external enthalpy controls, refer to the “Unit Options” section of the model-specific installation manual (refer to Table 1 on page 4).Dry Bulb Temperature ChangeoverWhen a unit is equipped with an economizer, an internal dry-bulb temperature changeover strategy can be selected. When this method is selected, the controller compares the OA Temp= value to the Economizer Changeover Set Point. The enthalpy control input is ignored in this case.To use the dry bulb method, the Economizer Changeover Flag must be set to “Dry Bulb.” The controller then uses the Economizer Changeover Set Point to determine whether or not outdoor air may be used for cooling. If the OA Temp= value is less than or equal to this set point, economizer cooling is enabled (OA Ambient= parameter indicates “Low”). If the OA Temp= value rises above this set point by more than the Economizer Changeover Differential,

economizer cooling is disabled (OA Ambient= parameter indicates “High”) and the outdoor air dampers are driven to the Effective Minimum Outdoor Damper Position Set Point (refer to “Minimum Ventilation Control“ below).

Minimum Ventilation Control

During normal occupied operation, the outdoor air dampers are prevented from closing below the Effective Minimum Outdoor Damper Position Set Point. This is to ensure that a minimum amount of ventilation air is always supplied to the space.


Keypad/Display IDParameter NameMenu

Name Item Name

OA Damper

EconChgovr= Enthalpy Economizer Changeover Flag

EconChgovrT= 60 ºF Economizer Changeover Set Point

EconChgovrDiff= 1ºF Economizer Changeover Differential



Menu Name Item Name

OA Damper

Eff Min OA Pos= ___%Effective Minimum Outdoor Damper Position Set Point

MinOA Type= NoneMinimum Outdoor Damper Position

Reset Flag

DesignFlow= No DesignFlow Flag

MinOA Pos= 10%Minimum Outdoor

Damper Position Set Point

MinOA Flow= 2000 CFM Minimum Outdoor Airflow Set Point

MinOA @Max Sig= 50%

Outdoor Damper Position Set Point at Maximum External

Signal

Min Signal= 0% Minimum External OA Reset Signal

Max Signal= 100% Maximum External OA Reset Signal

MinOA ResetMax= 50%

Effective Minimum Outdoor Damper Position Set Point

Maximum Limit

Max Fan Diff= 50% Maximum Fan Capacity Differential

Min Fan Diff= 20% Minimum Fan Capacity Differential

Reset T Limit= 0°F OA Reset Temperature Limit

DesignFlow Setup

Wait Time= 0 sec DesignFlow Wait Time

Modband= 50% DesignFlow Modulation Band

Max Step= 5% DesignFlow Maximum Step

Deadband= 6% DesignFlow Deadband

OM-137-2 79

Note: During the Off, Startup, Recirc, and MWU operat-ing states, the Effective Minimum Outdoor Damper Position Set Point is set to 0%.

The Effective Minimum Outdoor Damper Position Set Point can be reset between the Minimum Outdoor Damper Position Set Point and the Effective Minimum Outdoor Damper Position Set Point Maximum Limit in a number of ways. These are described as follows:Unoccupied OperationWhenever the unit is operating in the unoccupied operating states UnocEcon, UnocClg, or UnocHtg, the Effective Minimum Outdoor Damper Position Set Point is set to 0%.No Minimum OA ResetWhen the Minimum Outdoor Damper Position Reset Flag is set to “None” and the DesignFlow Flag is set to “No”, the Effective Minimum Outdoor Damper Position Set Point is set equal to the Minimum Outdoor Damper Position Set Point.External OA ResetThe Effective Minimum Outdoor Damper Position Set Point can be reset via a field supplied analog voltage or current signal. This signal can be in the range of 0-10 VDC or 0-20 mA. When the Minimum Outdoor Damper Position Reset Flag is set to “Ext V” or “Ext mA”, the Effective Minimum Outdoor Damper Position Set Point varies linearly between the Minimum Outdoor Damper Position Set Point and the Outdoor Damper Position Set Point at Maximum External Signal as the field voltage or current signal varies between a minimum and maximum (or maximum and minimum) value.The range and type of field reset signal is configured using the Minimum External OA Reset Signal and the Maximum External OA Reset Signal and setting a jumper on the main control board associated with analog input MCB-AI07. The analog input jumper is placed in either the “voltage” or “current” position. When the jumper is in the “voltage” position, the range of the input signal can be from 0-10 VDC and when in the “current” position, 0-20 mA. The input range is scaled using the Minimum External OA Reset Signal and the Maximum External OA Reset Signal parameters. If for example, the field signal is to be 1-5 VDC, the Minimum External OA Reset Signal must be set to 10% since 1 VDC is 10% of the 0-10 VDC range. The Maximum External OA Reset Signal must be set to 50% since 5 VDC is 50% of the 0-10 VDC range.

Note: The previous example demonstrated “direct acting” reset where the Effective Minimum Outdoor Damper Position Set Point increases as the voltage or current signal increases. “Reverse acting” reset can be accomplished as well. In the previous exam-ple, if instead the Minimum External OA Reset Sig-nal were set to 50% and the Maximum External OA

Reset Signal where set to 10%, then the Effective Minimum Outdoor Damper Position Set Point would decrease as the voltage or current signal increases.

Refer to “External Outdoor Air Damper Reset Signal” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.

Note: The Minimum Outdoor Damper Position Reset Flag automatically reverts to “None” if the Design-Flow= parameter is set to “Yes”. This means exter-nal OA reset and Design Flow cannot be used at the same time.

Network OA ResetWhen the Minimum Outdoor Damper Position Reset Flag is set to “None” and the DesignFlow Flag is set to “No”, the Effective Minimum Outdoor Damper Position Set Point is set equal to the Minimum Outdoor Damper Position Set Point. The Minimum Outdoor Damper Position Set Point can then be set via a network signal to meet the outdoor air requirements. Discharge Fan Capacity OA ResetOn any VAV unit, a potential problem exists: At a given outdoor air damper position, the volume of outdoor air being introduced to the building varies as the discharge air volume varies. This means that, under certain conditions, an insufficient amount of outdoor air may be entering the air stream if a fixed minimum damper position is being used.To overcome this type of problem, the MicroTech II unit controller provides a discharge fan capacity outdoor air reset strategy, which automatically resets the Effective Minimum Outdoor Damper Position Set Point as the discharge fan vane position or VFD speed varies. If selected, this strategy assures that a nearly constant volume of outdoor air is entering the air stream at all times when the economizer is not active.The discharge fan capacity reset strategy is used when the Minimum Outdoor Damper Position Reset Flag is set to “Auto.” The Effective Minimum Outdoor Damper Position Set Point is then reset between the Minimum Outdoor Damper Position Set Point and 100% (limited by Effective Minimum Outdoor Damper Position Set Point Maximum Limit) to maintain a constant estimated outdoor air flow quantity as the discharge fan capacity changes. The Minimum Outdoor Damper Position Set Point value is used to determine the percentage of the unit maximum airflow that is used as the minimum outdoor air quantity. For example, if the unit maximum airflow capacity is 10,000 cfm and the Minimum Outdoor Damper Position Set Point is 10%, then the Effective Minimum Outdoor Damper Position Set Point is reset to maintain 1000 cfm of outdoor air.

80 OM-137-2

Table 35 illustrates the effect of discharge fan capacity reset on unit operation (all values are approximate) assuming that a VAV unit has a maximum airflow capacity of 10,000 cfm and that the Minimum Outdoor Airflow Set Point is set to 10%.

Note: The Minimum Outdoor Damper Position Reset Flag automatically reverts to “None” if the Design-Flow= parameter is set to “Yes”.

DesignFlow OA Airflow Measurement ResetWhen a unit is equipped with the optional DesignFlow outdoor air measuring system and the DesignFlow Flag is set to “Yes”, the Effective Minimum Outdoor Damper Position Set Point is adjusted based on the measured amount of outdoor air being brought into the unit. If that airflow is below the desired value, the Effective Minimum Outdoor Damper Position Set Point is increased and if that airflow is above the desired value, Effective Minimum Outdoor Damper Position Set Point is decreased. The Effective Minimum Outdoor Damper Position Set Point is limited between the Minimum Outdoor Damper Position Set Point and the Effective Minimum Outdoor Damper Position Set Point Maximum Limit.

Note: The DesignFlow flag can be set to “Yes” only when the unit is configured with the optional DesignFlow outdoor air measurement feature.

Note: The MinOA Type= parameter automatically reverts to “None” if the DesignFlow= parameter is set to “Yes”.

The current outdoor air for each of the two OA inlets is determined by comparing the resistance of the right and left airflow monitoring devices (input to MCB-AO7 and MCB-AO8 respectively). These resistances are compared to tabulated airflow data. The two CFM values are added together to determine the Current Flow (OA Flow=) value.At increments equal to the DesignFlow Wait Time, a Step Value is calculated. If the Flow Ratio (the ratio of the Current Flow to the Minimum Outdoor Airflow Set Point) is greater than 100% by more than half of the DesignFlow Deadband, the Effective Minimum Outdoor Damper Position Set Point is decreased by the Step Value. If the Flow Ratio is less than 100% by more than half of the DesignFlow Deadband, the Effective Minimum Outdoor Damper Position Set Point is increased by the Step Value.

The Step Value is determined using the smaller of the following two calculations:

Or

Where:

Note: The DesignFlow apparatus is calibrated at the fac-tory and does not require field calibration unless the Main Control Board (MCB) is replaced or repro-grammed or if DesignFlow components are replaced. For details regarding calibration of the DesignFlow apparatus, refer to the applicable model-specific installation and maintenance man-ual (refer to Table 1 on page 4).

Discharge/Return Fan Differential OA ResetWhen a unit is equipped with return air fan inlet vanes or a return fan VFD, it may be necessary to increase the amount of outdoor air if the difference between the discharge and return fan capacity gets to large. If this is not done the discharge air fan can potentially be “starved” for air. A discharge fan operating in a “starved” condition not only has difficulty meeting the system airflow requirements but may cause excessive vibration and/or damage to damper sets and/or the return fan motor or VFD. To overcome this type of problem, the MicroTech II unit controller provides a discharge/return fan differential OA reset strategy, which automatically resets the Effective Minimum Outdoor Damper Position Set Point as the difference between the discharge and return air fan capacity varies.The discharge/return fan OA reset strategy is automatically used when the difference between the discharge and return fan capacity exceeds the Minimum Fan Capacity Differential. When the difference is less than or equal to the Minimum Fan Capacity Differential, the Effective Minimum Outdoor Damper Position Set Point is set to the Minimum Outdoor Damper Position Set Point (unless it is reset higher by another one of the reset methods). As the fan differential varies between the Minimum Fan Capacity Differential and the Maximum Fan Capacity Differential, the Effective

Table 35: Minimum Outdoor Air Volume Control Example

Discharge Fan VFD Speed (%)

Discharge Fan Inlet Vane Position (%)

Outdoor Air Damper Position (%)

Approximate Discharge Air Volume (cf.)

Approximate Outdoor Air Intake Volume (cf.)

100 100 10 10,000 1,000

50 40 20 5,000 1,000

10 10 100 1,000 1,000

Step Value DesignFlow Maximum Step=

Step Value (Error) DesignFlow Maximum StepDesignFlow Modulation Band-------------------------------------------------------------------------=

Error Absolute Value of 100% Flow Ratio–=

OM-137-2 81

Minimum Outdoor Damper Position Set Point is reset between the Minimum Outdoor Damper Position Set Point and the Effective Minimum Outdoor Damper Position Set Point Maximum Limit.OA Reset OverrideUnder some conditions the discharge air can contain a high percentage of outdoor air when any of the available OA reset features are active. If the outdoor air is very cold, the discharge air could also become very cold, particularly if the unit is equipped with single stage heat or no heat. Therefore, very cold discharge temperatures could result unless some other provision is made for tempering the air. If no other provisions are available for tempering the air it may be necessary to override the outdoor air reset strategy if the discharge air becomes to cold.To allow for such a contingency, the MicroTech II controller is equipped with an OA Reset Temperature Limit. If the discharge air temperature drops below this adjustable limit by more than half the Clg Db= parameter in the Discharge Cooling menu, any of the OA reset functions (with the exception of the discharge/return fan differential OA reset function) are overridden and the Effective Minimum Outdoor Damper Position Set Point is reset to maintain the discharge air temperature at this limit.

Note: This temperature override function is disabled when the OA Reset Temperature Limit is set to 0°F and when the unit is in the Cooling operating state.

Once the OA reset override function is active, normal control resume as follows:1. If the Minimum Outdoor Damper Position Reset Flag is

set to “Auto”, normal control resumes if the Effective Minimum Outdoor Damper Position Set Point is more than 2% above the calculated position based on the dis-charge fan capacity OA reset function for more than two minutes. Refer to “Discharge Fan Capacity OA Reset” on page 80.

2. If the Minimum Outdoor Damper Position Reset Flag is set to “Ext mA” or “Ext V”, normal control resumes if the Effective Minimum Outdoor Damper Position Set Point is more than 2% above the calculated position based on the external OA reset function for more than two minutes. Refer to “External OA Reset” on page 80.

3. If the DesignFlow Flag is set to “Yes”, normal control resumes if the Flow Ratio exceeds 100% by more than half the DesignFlow Deadband for more than two min-utes. Refer to “DesignFlow OA Airflow Measurement Reset” on page 81.

Cooling: MultistageTemperature Control

Entering Cooling Operating StateThe unit enters the Cooling operating state from the Recirc or Fan Only operating state when the Ctrl Temp= value rises above the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band, the Disch Air= parameter is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band and economizer operation is not available. The unit enters the Cooling operating state from the Econo operating state as describe in “Economizer to Cooling Operating State” on page 78.When the unit is in the Cooling operating state, cooling stages are turned on and off to maintain the discharge air temperature at the Effective Discharge Cooling Set Point.


The controller activates the first stage of mechanical cooling as it enters the Cooling operating state. The controller then stages compressor stages up or down as required to maintain the discharge air temperature at the Effective Discharge Cooling Set Point using either the “Nearest” or “Average” control method. The control method is selected by setting the Discharge Cooling Method Flag. For details regarding the “Average” and “Nearest” control methods refer to “Nearest DAT Compressor Staging” on page 83 or “Average DAT Compressor Staging” on page 85 as applicable.



Menu Name Item Name


Enable Set Point


Discharge Cooling

Eff Clg Spt= ___ °F Effective Discharge Cooling Set Point

DAT Clg Spt= 55.0 ºF Discharge Cooling Set Point


Compressor SetupClg Method= Average Discharge Cooling

Method Flag

Stage Time= 5 min Cooling Interstage Timer

82 OM-137-2

Cooling to Econo Operating StateThe unit will transition from the Cooling to Econo operating state if economizer operation is available when the Disch Air= parameter is below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band and the cooling capacity has been at 0% for longer than the Cooling Interstage Timer period.The unit will also transition from the Cooling to Econo operating state if economizer operation is available and compressor operation be comes disabled as describe in “Low Ambient Cooling Lockout” on page 87 below. Cooling to Fan Only Operating StateThe unit will transition from the Cooling to Fan Only operating state when economizer operation is not available, the Disch Air= parameter is below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band and the cooling capacity has been at 0% for longer than the Cooling Interstage Timer period.The unit will also transition from the Cooling to Fan Only operating state if the Ctrl Temp= parameter falls below the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band.The unit will also transition from the Cooling to Fan Only operating state if compressor operation is disabled as described below in “Low Ambient Cooling Lockout” on page 87 and economizer operation is not available.Nearest DAT Compressor StagingA cooling stage change can only occur after the Cooling Interstage Timer has expired and if the discharge air temperature is above or below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band (unless the unit is shut down or when cooling is disabled). These constraints on compressor staging are essential for preventing short cycling, which can reduce compressor life by causing improper oil return and excessive heat buildup in the motor windings. After these two conditions have been met, a stage change occurs whenever such a change will result in the discharge air temperature being closer to the Effective Discharge Cooling Set Point. This method results in fewer stage changes and hence fewer changes in the discharge air temperature and airflow delivered to the zones. This method may be more desirable in an application with zones whose cooling loads can be met with discharge air temperatures close to the Effective Discharge Cooling Set Point.To determine whether or not a stage change is made, the controller first calculates a DAT Difference. The DAT Difference is the change in the discharge air temperature between the time that the last stage change was made and the Cooling Interstage Timer expires (limited to 20°F). The assumption is that the discharge air temperature changes by this amount if the previous stage change is reversed. The controller also calculates a DAT Error. The DAT Error is the current difference between the discharge air temperature and

the Effective Discharge Cooling Set Point. If the DAT Error equals half of the DAT Difference, a stage change should result in a discharge air temperature on the other side of the Effective Discharge Cooling Set Point with the same DAT Error. Therefore, the discharge air temperature should be closer to the Effective Discharge Cooling Set if the DAT Difference is less than twice the DAT Error. Compressor staging is slightly biased to maintain the discharge air temperature toward the low side.During normal operation, the number of stages cannot change while the discharge temperature is within the range around the Effective Discharge Cooling Set Point defined by the Discharge Cooling Dead Band. Typically, during periods of constant cooling load, cooling is alternately staged up and down between the two stages that cause the discharge air temperature to fluctuate closely above and below the Effective Discharge Cooling Set Point. During periods of increasing or decreasing cooling load, two or more consecutive stage-up actions or stage-down actions can occur. The following are descriptions of the four possible consecutive stage changes when the “Nearest” control method is active.

Stage-Down to Stage-Up. A stage increase occurs after a stage decrease if all of the following are true:1. Discharge Air Temperature is above the Effective Dis-

charge Cooling Set Point by more than half the Dis-charge Cooling Dead Band

2. Cooling Interstage Timer has expired3. DAT Error > (DAT difference/2)*

Stage-Up to Stage-Down: A stage decrease occurs after a stage increase if all of the following are true:1. Discharge Air Temperature is below the Effective Dis-

charge Cooling Set Point by more than half the Dis-charge Cooling Dead Band

2. Cooling Interstage Timer has expired3. DAT Error > (DAT difference/2)+1°F

Stage-Up to Stage-Up. A stage increase occurs after a stage increase if both the following are true:1. Discharge Air Temperature is still above the Effective

Discharge Cooling Set Point by more than half the Dis-charge Cooling Dead Band

2. Cooling Interstage Timer has expired

Stage-Down to Stage-Down: A stage decrease occurs after a stage decrease if both the following are true:1. Discharge Air Temperature is still below the Effective

Discharge Cooling Set Point by more than half the Dis-charge Cooling Dead Band

2. Cooling Interstage Timer has expiredNote that a stage-down from stage 1 to stage 0 can occur. During stage 0 operation, all cooling stages are off but the controller remains in the Cooling operating state. After the Cooling Interstage Timer expires, another stage-down would cause the controller to leave the Cooling operating state.

OM-137-2 83

*This retirement does not apply when staging from stage 0 to stage 1

Figure 9: Nearest Discharge Air Control Method Illustration

Nearest Discharge Control Method IllustrationThe following is an illustration of the “Nearest” compressor staging control method. This illustration is meant to show a variety of staging possibilities, not normal unit operation. Refer to Figure 9, which shows nine points on a graph of the discharge air temperature changing with time. The Cooling Interstage Timer setting is 5 minutes in this illustration.

Point 1. Assume that the controller has just staged up cooling. As a result, the discharge air temperature begins to drop and the Cooling Interstage Timer is reset.

Point 2. The Cooling Interstage Timer has not yet expired, nor is the discharge air temperature below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band, therefore, no staging action occurs.

Point 3. The Cooling Interstage Timer has expired. The discharge air temperature is below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band. However, the DAT Error is not greater than [(DAT Difference/2) +1]. Therefore, no staging action is taken.

Point 4. The Cooling Interstage Timer has expired. The discharge air temperature is below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band and the DAT Error is greater than [(DAT Difference/2) +1]. Therefore, cooling is staged down one stage. Note that the elapsed time since the last stage change in this illustration is 7.25 minutes.

Point 5. The Cooling Interstage Timer has expired. The discharge air temperature is below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band. Since the previous stage change was down, cooling is again staged down a stage.

Point 6. The Cooling Interstage Timer has expired but the discharge air temperature is within the Discharge Cooling Dead Band around the Effective Discharge Cooling Set Point. Therefore, no staging action is taken.

Point 7. The Cooling Interstage Timer has expired. The discharge air temperature is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band, however, the DAT Error is not greater than the DAT Difference/2. Therefore, no staging action is taken.

Point 8. The Cooling Interstage Timer has expired. The discharge air temperature is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band and the DAT Error is greater than DAT Difference/2. Therefore, cooling is staged up one stage. Note that the elapsed time since the last stage change in this illustration is 11.0 minutes.

Point 9. The Cooling Interstage Timer has expired. The discharge air temperature is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band. Since the previous stage change was up, cooling is again staged up a stage.

1

2 3

45

6

78

9

5 5 5 5 5

Discharge CoolingDead Band

7.25 11.0

Time (Minutes)

Dis

ch

arg

eA

irTem

pera

ture

Stage Up

No Action(Withindead bandandInterstageTimer notexpired)

No Action(DAT Error notgreater than[DAT Difference/2]+1

StageDown(Previouschangewasdown)

No Action(Within deadband)

No Action(DAT Error notgreater thanDAT Difference/2)

Stage Up(DAT Errorgreater thanDATDifference/2)

Stage Up(Previouschange wasup)

Stage Down(DAT Errorgreater than[DAT Difference]+1)

Effective DischargeCooling Set Point

84 OM-137-2

Average DAT Compressor StagingThis staging method is useful if the average discharge air temperature over time can be maintained at the Effective Discharge Cooling Set Point to meet the cooling load of one or more spaces.A cooling stage change can only occur after the Cooling Interstage Timer has expired and the discharge air temperature is above or below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band (unless the unit is shut down or cooling is disabled). These constraints on compressor staging are essential for preventing short cycling, which can reduce compressor life by causing improper oil return and excessive heat buildup in the motor windings. After these two conditions have been met, staging occurs as the controller attempts to equalize two running totals: degree-time above set point (DTA) and degree-time below set point (DTB).Approximately Every 15 seconds the controller measures the number of degrees the discharge air temperature is above the Effective Discharge Cooling Set Point. If above the set point, each new measurement is added to a running total, named DTA.Approximately Every 15 seconds the controller measures the number of degrees the discharge air temperature is below the Effective Discharge Cooling Set Point. If below the set point, each new measurement is added to a running total, named DTB.During normal operation, the number of stages does not change while the discharge temperature is within the range around the Effective Discharge Cooling Set Point defined by the Discharge Cooling Dead Band. Typically, during periods of constant cooling load, cooling is alternately staged up and down between the two stages that cause the discharge air temperature to fluctuate closely above and below the Effective Discharge Cooling Set Point. During periods of increasing or decreasing cooling load, two or more consecutive stage-up actions or stage-down actions can occur. The following are descriptions of the four possible consecutive staging changes when “Average” control is active.

Stage-Up to Stage-Down: After a stage-up occurs, the discharge air temperature usually begins to drop toward set point. DTA accumulates and continues to do so until the Effective Discharge Cooling Set Point is reached. When the discharge air temperature drops below the Effective Discharge Cooling Set Point, DTA stops accumulating and DTB starts accumulating. When DTB equals or exceeds DTA, a stage-down occurs if the Cooling Interstage Timer has expired and the discharge air temperature is below the Effective Discharge Cooling Set Point by more than half the

Discharge Cooling Dead Band. (If either staging constraint has not been met, a stage down cannot occur and DTB continues accumulating.) After the stage-down occurs, the DTA value is subtracted from both DTA and DTB. As a result, DTA is zeroed and DTB is either zeroed or reduced by the DTA amount. The Cooling Interstage Timer is reset and degree-time accumulation resumes.

Stage-Down to Stage-Up: After a stage-down occurs, the discharge air temperature usually begins to rise toward the Effective Discharge Cooling Set Point. DTB accumulates and continues to do so until the Effective Discharge Cooling Set Point is reached. When the discharge air temperature rises above the Effective Discharge Cooling Set Point, DTB stops accumulating and DTA starts accumulating. When DTA equals or exceeds DTB, a stage-up occurs if the Cooling Interstage Timer has expired and the discharge air temperature is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band. (If either staging constraint has not been met, a stage up cannot occur and DTA continues accumulating.) After the stage-up occurs, the DTB value is subtracted from both DTB and DTA. As a result, DTB is zeroed and DTA is either zeroed or reduced by the DTB amount. The Cooling Interstage Timer is reset and degree-time accumulation resumes.

Stage-Up to Stage-Up: If the cooling load increases after a stage-up occurs, the discharge air temperature may drop for a while and then rise again. Regardless of the DTA and DTB values, another stage-up occurs if the discharge air temperature is still above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band after the Cooling Interstage Timer expires. After the stage-up occurs, DTA and DTB are zeroed. The Cooling Interstage Timer is reset and degree-time accumulation resumes.

Stage-Down to Stage-Down: If the cooling load decreases after a stage-down occurs, the discharge air temperature may rise for a while and then drop again. Regardless of the DTA and DTB values, another stage-down occurs if the discharge air temperature is still below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band after the Cooling Interstage Timer expires. After the stage-down occurs, DTA and DTB are zeroed. The Cooling Interstage Timer is reset and degree-time accumulation resumes.Note that a stage-down from stage 1 to stage 0 can occur. During stage 0 operation, all cooling stages are off but the controller remains in the Cooling operating state. After the Cooling Interstage Timer expires, another stage-down would cause the controller to leave the Cooling operating state.

OM-137-2 85

Figure 10: Average Discharge Air Control Method Illustration

Average Discharge Control Method IllustrationThe following is an illustration of the “Average” compressor staging control method. This illustration is meant to show a variety of staging possibilities, not normal unit operation. Refer to Figure 10, which shows nine points on a graph of the discharge air temperature changing with time. The Cooling Interstage Timer setting is 5 minutes in this illustration.

Point 1. Assume that the controller has just staged up and that DTA and DTB are zero. As a result, the discharge air temperature drops and the Cooling Interstage Timer is reset.

Point 2. DTA (Area A) equals DTB (Area B). The discharge air temperature is below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band. However, since the Cooling Interstage Timer has not yet expired, no staging action occurs.

Point 3. The Cooling Interstage Timer has expired. DTB (Area B + Area C) is greater than DTA (Area A) and the discharge air temperature is below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band. Therefore, cooling is staged down. As a result, the discharge air temperature rises, the Cooling Interstage Timer is reset, and DTA is subtracted from both DTA and DTB. This zeros DTA and leaves DTB equal to Area C.

Point 4. The Cooling Interstage Timer has expired. The discharge air temperature is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band. However, since DTA (Area E) is not yet equal to DTB (Area C + Area D), no staging action occurs and the discharge air temperature continues to rise.

Point 5. The Cooling Interstage Timer has expired. The discharge air temperature is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band and DTA (Area E + Area F) is equal to DTB (Area C + Area D). Therefore, cooling is staged up. As a result, the discharge air temperature drops, the Cooling Interstage Timer is reset, and DTB is subtracted from both DTB and DTA. This zeros both DTA and DTB since they are equal. Note that the elapsed time since the last stage change in this illustration is 6.3 minutes.

Point 6. The Cooling Interstage Timer has expired. Because the cooling load is now increasing, the discharge air temperature does not fall below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band. No staging action occurs for two reasons: (1) the discharge air temperature is within the Discharge Cooling Dead Band and (2) DTB (Area H) is not yet equal to DTA (Area G). Even if the discharge air temperature falls below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band (as shown just after Point 6), a stage down does not occur because DTB remains less than DTA. The discharge air temperature starts rising again because the load is increasing.

Point 7. The discharge air temperature is again above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band. Since the Cooling Interstage Timer expired at Point 6, cooling is staged up. As a result, both DTA and DTB are zeroed and the Cooling Interstage Timer is reset. Note that DTA and DTB are both zeroed since two consecutive stage increase actions occurred. The discharge air temperature continues to rise, however,

5 5 5 5 5

1

23

4 5

6

78

9

A

B C D

E F

HI

J K L

M

StageUp

No Action(A = B),InterstageTimer notexpired

StageDown

NoActionStageUp [(C + D = (E + F)]and InterstageTimer is expired

No ActionInsidedeadband

Stage UpStage Up

Stage Down(L=M)

Discharge CoolingDead Band

Effective DischargeCooling Set Point

11.36.3

Time (Minutes)

Dis

char

ge A

ir Te

mpe

ratu

re

G

86 OM-137-2

because the cooling load is still increasing. Note that the elapsed time since the last stage change in this illustration is 11.0 minutes.

Point 8. The Cooling Interstage Timer has expired. Since the discharge air temperature is still above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band, another stage-up occurs. As a result, DTA (Area K) is again zeroed out (DTB remains zeroed) and the Cooling Interstage Timer is reset. The cooling load has leveled out, and the discharge air temperature drops.

Point 9 . The Cooling Interstage Timer has expired at the same time that DTB (Area M) becomes equal to DTA (Area L). Therefore, cooling is staged down, the Cooling Interstage Timer is reset and DTA is subtracted from both DTA and DTB. This zeros both DTA and DTB since they are equal.

Low Ambient Cooling Lockout

Mechanical cooling is disabled when the outdoor air temperature is below the Low Ambient Cooling Lockout Set Point. When this occurs, the Clg Status= parameter indicates either “Econo” or “Off Amb” if all cooling is not disabled for some other reason. When the outdoor air temperature rises above the Low Ambient Cooling Lockout Set Point by more than the Low Ambient Cooling Lockout Differential, compressorized cooling is re-enabled. The Clg Status= parameter indicates either “All Clg” or “Mech Clg” if all cooling is not disabled for some other reason.

Caution: Unless the unit is equipped with the SpeedTrol low ambient condenser fan control option, the Low Ambient Cooling Lockout Set Point should never be set below 45°F.

Compressor Staging

On units equipped with compressorized cooling, there are many different compressor staging configurations available,

depending upon unit size. For specific output staging information for the possible configurations, refer to the “Cooling Control Boards (CCB1, CCB2 or GCB1)” section of IM 696, MicroTech II Applied Rooftop Unit Controller.In most cases the unit can be configured to either cross-load the two cooling circuits or to stage up one circuit before the other. In either case, when possible, compressors are staged up and down to equalize run hours. Also, in most of the available unit staging configurations, circuit # 1 or circuit #2 can be designated as the “lead” circuit or the unit can be set for automatic “lead/lag” of the circuits. The circuit lead/lag, cross-circuit loading and lead-circuit loading functions are described in the following sections.Circuit Lead/Lag4 Compressors/4 Stages or 6 Compressor/6 Stages. The “lead” refrigeration circuit can be selected by setting the Circuit Lead/Lag Flag. When the Circuit Lead/Lag Flag is set to “Auto”, the “lead” refrigeration circuit alternates each time cooling is staged down until all the compressors are off. The refrigeration circuit with the compressor with the fewest run hours becomes the “lead.”When the Circuit Lead/Lag Flag is set to “#1”, circuit #1 always acts as the “lead.” When the Circuit Lead/Lag Flag is set to “#2”, circuit #2 always acts as the “lead.”

Caution: Automatic lead/lag or circuit #2 lead operation should not be used if the unit is equipped with the hot gas bypass option on circuit #1 only.

2 Compressors/3 Stages or 3 Compressors/4 Stages. Circuit lead/lag operation does not apply to these staging configurations and the Circuit Lead/Lag Flag has no affect on the unit operation.

2 Compressors/4 Stages, 2 Compressors/6 Stages, 4 Compressors/8 Stages. The “lead” refrigeration circuit can be selected by setting the Circuit Lead/Lag Flag. When the Circuit Lead/Lag Flag is set to “Auto”, the “lead” refrigeration circuit alternates each time cooling is staged down until all compressors are off. The refrigeration circuit with the lower run hours then becomes the “lead.” When the Circuit Lead/Lag Flag is set to “#1” circuit #1 always acts as the “lead.” When the Circuit Lead/Lag Flag is set to “#2” circuit #2 always acts as the “lead.”

Note: In these cooling staging configurations, circuit #1 run hours are considered equal to the run hours of compressor #1 and circuit #2 run hours are consid-ered equal to the run hours of compressor #2.

Caution: Automatic lead/lag or circuit #2 lead operation should not be used if the unit is equipped with the hot gas bypass option on circuit #1 only.

Cross Circuit LoadingWhen the Circuit Staging Method Flag is set to “Cross Circ”, the two circuits are loaded and unloaded as evenly as possible. There are some differences in “Cross Circuit”



Menu Name Item Name

Zone Cooling

OATComp Lock= 55.0 ºF Low Ambient Cooling Lockout Set Point

OATLock Diff= 3.0 °FLow Ambient Cooling

Lockout Set Point Differential



Menu Name Item Name

Compressor SetupLead Circuit= # 1 Circuit Lead/Lag Flag

CompCtrl= Cross Circ Circuit Staging Method Flag

OM-137-2 87

staging method depending on the unit compressor stage configuration.

4 Compressors/4 Stages or 6 Compressor/6 Stages. When a capacity increase is required and the number of operating compressors in both circuits is the same, the compressor in the “lead” circuit with the fewest run hours that is not operating is turned on. When a capacity increase is required and the number of compressors in the two circuits is not the same, the compressor with the fewest run hours in the circuit with the fewest operating compressors is turned on.When a capacity decrease is required and the number of operating compressors in both circuits is the same, the operating compressor with the highest run hour total in the “lag” circuit is turned off. When a capacity decrease is required and the number of operating compressors in the two circuits is not the same, the operating compressor with the most run hours in the circuit with most operating compressors is turned off.

Note: A disabled circuit remains at zero capacity. If the other circuit is enabled, the circuit capacity is con-trolled similar to the Lead-Loading method.

2 Compressors/4 Stages, 2 Compressors/6 Stages or 4 Compressors/8 Stages. When a capacity increase is required, the circuit operating at the lower capacity is staged up. If both circuits are operating at the same capacity, the “lead” circuit is staged up if not already at its maximum.When a capacity decrease is required, the circuit operating at the higher capacity is staged down. If both circuits are operating at the same capacity, the “lag” circuit is staged down.

Note: A disabled circuit remains at zero capacity. If the other circuit is enabled, it acts as the “lead” and the circuit capacity is controlled similar to the Lead-Loading method.

2 Compressors/3 Stages. With this staging configuration, the compressors are always controlled in the same way. There are no circuit “lead/lag”, “compressor run hour” or “Cross Circuit” variations to the staging sequence. Starting with 0% capacity, when a capacity increase is required, the “small” compressor on circuit #1 is turned on. When a further increase is required, the “large” compressor on circuit # 2 is turned on and the “small” compressor on circuit #1 is turned off. For the final capacity increase, the “small” compressor on circuit #1 is turned on while the “large” compressor on circuit #2 remains on.

Note: If the “small” compressor on circuit #1 is disabled, the “large” compressor on circuit # 2 operates when cooling is required and the cooling capacity is set to 66%. If the “large” compressor on circuit # 2 is dis-abled, the “small” compressor on circuit # 1 oper-ates when cooling is required and the cooling capacity is set to 33%.

3 Compressors/4 Stages. Units without low ambient capability (SpeedTrol) - Starting with 0% cooling capacity, when a capacity increase is required, the small compressor on circuit #1 with the fewest run hours is turned on (25%). When a further capacity increase is required, the large compressor on circuit #2 is turned on and the operating compressor on circuit #1 is turned off (50%). When a further capacity increase is required, the small compressor on circuit #1 with the fewest run hours is turned on (75%). For the final capacity increase the remaining compressor on circuit #1 is turned on (100%).Starting with 100% capacity, when a capacity decrease is required, the small compressor on circuit #1 with the most run hours is turned off (75%). When a further capacity decrease is required, the remaining small compressor on circuit #1 is turned off (50%). When a further capacity decrease is required, the large compressor on circuit #2 is turned off and the small compressor on circuit #1 with the fewest run hours is turned on (25%). When a further capacity decrease is required, the operating small compressor on circuit #1 is turned off (0%).

Note: If one of the “small” compressors on circuit #1 is disabled, the staging sequence remains the same except that the last stage increase would be unavail-able and the capacity would be limited to 75%. If both of the “small” compressors on circuit #1 are disabled, the “large” compressor on circuit #2 (50% capacity) would cycle on and off to maintain the load. If the “large” compressor on circuit #2 is dis-abled, the two “small” compressors on circuit #1 would cycle on and off (based on run hours) to maintain the load.

Units with low ambient capability (SpeedTrol) - Starting with 0% cooling capacity, when a capacity increase is required, the small compressor on circuit #1 with the fewest run hours is turned on (25%). When a further capacity increase is required, the remaining compressor on circuit #1 is turned on (50%). When a further capacity increase is required, the large compressor on circuit #2 is turned on and the small compressor on circuit #1 with the most run hours is turned off (75%). When a further capacity increase is required, the small compressor on circuit #1 that is not operating is turned on (100%). Starting with 100% capacity, when a capacity decrease is required, the small compressor on circuit #1 with the most run hours is turned off (75%). When a further capacity decrease is required, the large compressor on circuit #2 is turned off and the small compressor on circuit #1 that is not operating is turned on (50%). When a further capacity decrease is required, the small compressor on circuit #1 with the most run hours is turned off (25%). When a further capacity decrease is required, the operating small compressor on circuit #1 is turned off (0%).

88 OM-137-2

Lead Circuit LoadingWhen the Circuit Staging Method Flag is set to “Lead Load”, one circuit is loaded completely before the first compressor in the second circuit is turned on, and one circuit is unloaded completely before the other circuit begins to be unloaded. There are some differences in “Lead Load” staging method depending on the unit compressor stage configuration.

4 Compressors/4 Stages or 6 Compressor/6 Stages. When a capacity increase is required and the number of operating compressors is 0, the compressor in the “lead” circuit with the fewest run hours is turned on. When a capacity increase is required, the “lead” circuit is staged up if not already fully loaded. If the “lead” circuit is fully loaded, the compressor in the “lag” circuit with the fewest run hours is turned on. When a further capacity increase is required, the “lag” circuit is staged up. When a capacity decrease is required, the operating compressor in the “lag” circuit with the most run hours is turned off. This continues until the “lag” circuit is fully unloaded. When a further capacity decrease is required, the operating compressor in the “lead” circuit with the most run hours is turned off. This continues until the “lead” circuit is fully unloaded.

Note: A disabled circuit remains at zero capacity. If the other circuit is enabled, it acts as the “lead” and the circuit capacity is controlled using the Lead-Load-ing method.

2 Compressors/4 Stages, 2 Compressors/6 Stages or 4 Compressors/8 Stages. When a capacity increase is required and the “lead” circuit is not at maximum, the “lead” circuit is staged up. When a capacity increase is required and the “lead” circuit is already at its maximum, the “lag” circuit is staged up. When a capacity decrease is required and the “lag” circuit is not at zero capacity, the “lag” circuit is staged down. When a capacity decrease is required and the “lag” circuit is at zero capacity, the “lead” circuit is staged down.

Note: A disabled circuit remains at zero capacity. If the other circuit is enabled, it acts as the “lead” and the circuit capacity is controlled using the Lead-Load-ing method.

2 Compressors/3 Stages . With this staging configuration, the compressors are always controlled in the same way. There are no circuit “lead/lag”, “compressor run hour” or “Lead Load” variations to the staging sequence. Starting with 0% capacity, when a capacity increase is required, the “small” compressor on circuit #1 is turned on. When a further increase is required, the “large” compressor on circuit #2 is turned on and the “small” compressor on circuit #1 is turned off. For the final capacity increase, the

“small” compressor on circuit #1 is turned on while the “large” compressor on circuit #2 remains on.

Note: If the “small” compressor on circuit #1 is disabled, the “large” compressor on circuit #2 operates when cooling is required and the cooling capacity is set to 66%. If the “large” compressor on circuit #2 is dis-abled, the “small” compressor on circuit #1 oper-ates when cooling is required and the cooling capacity is set to 33%.

3 Compressors/4 Stages. Units without low ambient capability (SpeedTrol) - Starting with 0% cooling capacity, when a capacity increase is required, the large compressor on circuit #2 is turned on (Clg Capacity= value is set to 50%). When a further capacity increase is required, the small compressor on circuit #1 with the fewest run hours is turned on (75%). For the final capacity increase the remaining compressor on circuit #1 is turned on (100%).Starting with 100% capacity, when a capacity decrease is required, the small compressor on circuit #1 with the most run hours is turned off (75%). When a further capacity decrease is required, the remaining small compressor on circuit #1 is turned off (50%). When a further capacity decrease is required, the large compressor on circuit #2 is turned off (0%).

Note: If one of the “small” compressors on circuit #1 is disabled, the staging sequence remains the same except that the last stage increase would be unavail-able and the capacity would be limited to 75%. If both of the “small” compressors on circuit #1 are disabled, the “large” compressor on circuit #2 (50% capacity) would cycle on and off to maintain the load. If the “large” compressor on circuit #2 is dis-abled, the two “small” compressors on circuit #1 would cycle on and off (based on run hours) to maintain the load.

Units with low ambient capability (SpeedTrol) - Lead Circuit Loading is not valid on the 3 Compressors/4 Stages configuration. The staging sequence is always as described for units with low ambient capability (SpeedTrol) in the Cross Circuit Loading section.Generic Condensing Unit StagingWhen a unit is equipped with a DX cooling coil and is interfaced with a field supplied condensing unit, it is equipped with a generic condenser control board (GCB1) for controlling the cooling stages on the condensing unit. In this case, circuit lead/lag, cross-circuit loading and lead-circuit loading are not applicable. The outputs on the condenser control board (GCB1) are simply staged up and down sequentially as the cooling capacity changes.

OM-137-2 89

Air-cooled Condenser Fan Control

On units equipped with compressorized cooling and an air-cooled condensing section, there are up to four steps of condenser fan operation per cooling circuit depending on the size of the unit. The fans in each circuit are started and stopped based on outdoor air temperature when circuit is operating. The first condenser fan step in each operating circuit is turned on when the OA Temp= value rises above the First Condenser Fan Set Point and is turned off when the OA Temp= value falls below the First Condenser Fan Set Point by more than the Condenser Fan Differential. The second condenser fan step in each operating circuit is turned on when the OA Temp= value rises above the Second Condenser Fan Set Point and is turned off when the OA Temp= value falls below the Second Condenser Fan Set Point by more than the Condenser Fan Differential. The third condenser fan step in each operating circuit is turned on when the OA Temp= value rises above the Third Condenser Fan Set Point and is turned off when the OA Temp= value falls below the Third Condenser Fan Set Point by more than the Condenser Fan Differential. The fourth condenser fan step in each operating circuit is turned on when the OA Temp= value rises above the Fourth Condenser Fan Set Point

and is turned off when the OA Temp= value falls below the Fourth Condenser Fan Set Point by more than the Condenser Fan Differential.The condenser fan set points must be set to specific values that depend on the unit model sized according toTable 40 (R22) or Table 41 (R407)

Table 40: Condenser Fan Ambient Setpoints - Units with R22 Refrigerant



Menu Name Item Name

Compressor Setup

Cond Fan1 Spt= 0°F First Condenser Fan Set Point

Cond Fan2 Spt= 55°F Second Condenser Fan Set Point

Cond Fan3 Spt= 65°F Third Condenser Fan Set Point

Cond Fan4 Spt= 75°F Fourth Condenser Fan Set Point

Cond Fan Diff= 5°F Condenser Fan Differential

Unit Size

Cond. Fan # 1 Setpoint

(°F)


(°F)


(°F)


(°F)

015 0 60 NA NA

018 0 60 NA NA

020 0 60 NA NA

025 0 65 NA NA

030 0 65 NA NA

036 0 70 NA NA

040 0 65 NA NA

045 0 65 NA NA

050 0 60 NA NA

060 0 25 70 NA

070 (Recip) 0 25 70 NA

070(Scroll) 0 40 70 NA

075 0 65 75 0

080 0 65 75 0

090 0 65 75 0

105 0 0 58 70

115 0 0 55 75

125 0 65 35 80

135 0 55 25 65

90 OM-137-2

Table 41: Condenser Fan Ambient Setpoints - Units with R407 Refrigerant

Evaporative Condenser Fan Control


When a unit is equipped with an evaporative condensing section, there are up to three steps of condenser fan operation per cooling circuit. This option may include a single VFD used to control the speed of the first condenser fan on both circuits. The VFD is controlled directly via a communication interface between the main controller and the VFD. The

following describes the condenser fan control for units with and without the optional VFD.Condenser Fan Operation without VFDWhen the first compressor on the “lead” cooling circuit is turned on, condenser fan step one is turned on as soon as the Sump Temp= value rises above the Maximum Condenser Sump Temperature. The unit then stages up and down between condenser fans steps 0, 1, 2 and 3 as the Sump Temp= value changes. If the Condenser Fan Stage Timer has expired since the last stage change and the Sump Temp= value rises above the Maximum Condenser Sump Temperature, the condenser fan step is increased. If the Condenser Fan Stage Timer has expired since the last stage change and the Sump Temp= value drops below the Minimum Condenser Sump Temperature, the condenser fan step is decreased. When at least one compressor is operating on the both circuits, the condenser fan step on the “lag” circuit is set equal to that of the “lead” circuit so that the condensers fans on both circuits step up and down together.

Note: If the condenser fan operation steps to 0, it is not required that the Condenser Fan Stage Timer has expired before staging back up to step 1 when the Sump Temp= value rises again above the Maximum Condenser Sump Temperature.

Condenser Fan Operation with VFDWhen the evaporative condenser option includes a VFD, the condenser fan staging is similar to that describe above with the following exceptions:1. When the first compressor on the “lead” cooling circuit

is turned on, the first fan on both circuits (they are both controlled by the same VFD) are turned on immediately regardless of the Sump Temp= value and whether or not a compressor is running on the “lag” circuit.

2. When operating, the speed of the VFD varies according to the following formula:

VFD Speed = Minimum Condenser Fan Speed + (Sump Temperature - Minimum Condenser Sump Temperature) X (100% - Minimum Condenser Fan Speed) / (Maximum Condenser Sump Temperature - Minimum Condenser Sump Temperature)

Evaporative Condenser Sump Pump ControlWhen a unit is equipped with an evaporative condensing section, water is pumped from a sump beneath the condenser tubes to nozzles above the condenser coil that spray water onto the banks of condenser coil tubes. The controller starts the sump pump whenever the unit enters the Cooling operating state by turning on a “cooling enable” output on the MCB (MCB-BO7). This output energizes a sump pump relay that in turn energizes the sump pump contactor. A low water switch monitors the water level in the sump. The pump remains running as long as this switch indicates an acceptable water level and the sump pump relay is energized.

Unit Size

Cond. Fan # 1

Setpoint (°F)


(°F)


(°F)


(°F)

015 0 60 NA NA

018 0 0 NA NA

020 0 0 NA NA

025 0 65 NA NA

030 0 65 NA NA

036 0 65 NA NA

040 0 60 NA NA

045 0 55 NA NA

050 0 50 NA NA

060 0 15 70 NA

070 0 30 70 NA

075 0 65 75 0

080 0 65 75 0

090 0 65 75 0

105 0 0 52 70

115 0 0 45 75

125 0 55 30 80

135 0 45 20 65


Menu Name Menu Item

Evap Condensing

Min Fan Speed= 25% Minimum Condenser Fan Speed

Min SumpT= 75°F Minimum Condenser Sump Temperature

Max SumpT= 85°F Maximum Condenser Sump Temperature

Sump Dump Spt Sump Dump Set Point

Stage Time= 10 min Condenser Fan Stage Timer

OM-137-2 91

If the sump temperature gets too cold, the sump is emptied to prevent freezing. If the SumpTemp= value drops below the Sump Dump Set Point, output 8 on the cooling control boards (CCB1-B08 & CCB2-B08) is energized, opening the sump dump valve, emptying the sump. When the SumpTemp= value rises back above the Sump Dump Set Point by more than a fixed 3° F differential, the sump valve is closed allowing the sump to be refilled.

Circuit PumpdownNormal Circuit PumpdownDuring normal cooling circuit operation, the circuit is pumped down when the last compressor in the circuit is shut down due to normal staging. It is also pumped down if the entire circuit is shut down due to any alarms other than Hi Pres-Ckt1, Hi Pres-Ckt2, Comp# 1 Alm, Comp# 2 Alm, Comp# 3 Alm, Comp# 4 Alm, Comp# 5 Alm, and Comp# 6 Alm.When pumpdown is required for a circuit, the Liquid Line Solenoid Valve for that circuit is closed (output turned off) and a compressor on that circuit operates until the circuit low pressure switch opens at which time the compressor is turned off. If the low pressure switch does not open within 180 seconds, pumpdown is terminated by turning off the compressor and the PumpDown-Ckt1 (or PumpDown-Ckt2) problem alarm is generated.Manual Circuit PumpdownCompressors in a Circuit are Operating: Circuit pumpdown is manually initiated if either the master pumpdown switch (PS3) in the main control panel or the circuit pumpdown switch (PS1-Circuit #1 or PS2-Circuit #2) in the condenser control panel is placed in the Pumpdown (Off) position.

Compressors in a Circuit are not Operating: Circuit pumpdown is manually initiated if either the master pumpdown switch (PS3) or the circuit pumpdown switch (PS1-Circuit #1 or PS2-Circuit #2) is cycled from the Auto (On) to the Pumpdown (Off) position twice in less than 20 seconds and the low pressure switch is closed. When pumpdown is initiated for a circuit, the liquid line solenoid valve for that circuit is closed (output turned off) and a compressor on that circuit operates until the circuit low pressure switch opens at which time the compressor is turned off. If the low pressure switch does not open within 180 seconds, pumpdown is terminated by turning off the compressor and the PumpDown-Ckt1 (or PumpDown-Ckt2) problem is generated.

Cooling: ModulatingTemperature Control

Entering Cooling Operating StateThe unit enters the Cooling operating state from the Recirc or Fan Only operating state when the Ctrl Temp= value rises above the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band, the Disch Air= parameter is above the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band and economizer operation is not available. The unit enters the Cooling operating state from the Econo operating state as describe in “Economizer to Cooling Operating State” on page 78.When the unit is in the Cooling operating state, cooling capacity is modulated to maintain the discharge air temperature at the Effective Discharge Cooling Set Point.


Chilled Water: Valve Control. When a unit is equipped with chilled water cooling and is in the Cooling operating state, the chilled water valve is modulated to maintain the discharge air temperature at the Effective Discharge Cooling Set Point. The controller modulates the chilled water valve using three PID control loop parameters to modulate the valve as the discharge air temperature changes. Theses are the Cooling Proportional Band, Cooling Integral Time and Cooling Period. Although these parameters can be adjusted, for most applications, the factory default values for these



Menu Name Item Name


Enable Set Point


Discharge Cooling

Eff Clg Spt= ___ ºF Effective Discharge Cooling Set Point

DAT Clg Spt= 55°F Discharge Cooling Set Point


Chilled Water Setup

Clg Propbd= 30.0 ºF Cooling Proportional Band

Clg IntTime= 100 sec Cooling Integral Time

Clg Period= 30 sec Cooling Period

Stage Timer= 5 min Cooling Interstage Timer

92 OM-137-2

parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.

Chilled Water: Face and Bypass Damper Control. When a unit is equipped with chilled water face and bypass damper control and is in the Cooling operating state, the chilled water valve is driven fully open and the face and bypass dampers are modulated to maintain the discharge air temperature at the Effective Discharge Cooling Set Point. The controller modulates the face and bypass dampers using three PID control loop parameters as the discharge air temperature changes. Theses are the Cooling Proportional Band, Cooling Integral Time and Cooling Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.Cooling to Econo Operating StateThe unit will transition from the Cooling to Econo operating state if economizer operation is available when the Disch Air= parameter is below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band and the chilled water valve has been closed (or the face and bypass dampers have been closed to the face) for longer than the Cooling Interstage Timer period.The unit will also transition from the Cooling to Econo operating state if economizer operation is available and mechanical cooling operation be comes disabled as describe in “Low Ambient Cooling Lockout” on page 87. Cooling to Fan Only Operating StateThe unit will transition from the Cooling to Fan Only operating state when economizer operation is not available, the Disch Air= parameter is below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band and the chilled water valve has been closed (or the face and bypass dampers have been closed to the face) for longer than the Cooling Interstage Timer period.The unit will also transition from the Cooling to Fan Only operating state if the Ctrl Temp= parameter falls below the Effective Cooling Enable Set Point by more than half the Cooling Enable Dead Band.The unit will also transition from the Cooling to Fan Only operating state if mechanical cooling operation is disabled as described in “Low Ambient Cooling Lockout” on page 87 and economizer operation is not available.

Heating: One StageTemperature Control

Entering Heating Operating StateThe unit enters the Heating operating state from the Fan Only operating state when the Ctrl Temp= value falls below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band. When the unit is in the Heating operating state, the single heating stage is turned on and remains on.

Note: The Effective Heating Enable Set Point is set by the controller equal to the Heating Enable Set Point.

Heating to Fan Only Operating StateThe unit transitions from Heating to Fan Only and the single heat stage is turned off when the Ctrl Temp= value rises above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band. The unit will also transition from the Heating to Fan Only operating state if heating operation is disabled as described below in “High Ambient Heating Lockout” on page 94.

Note: Unlike units equipped with a modulating or multi-stage heat source, there is no minimum discharge temperature low limit function (MinDAT) available with the single stage (or no heat) unit configuration. This should be considered when setting or resetting the Eff Min OA Pos= parameter as described in “Minimum Ventilation Control” on page 77 (0-30% outdoor air units) or “Minimum Ventilation Con-trol” on page 79 (economizer units).


Keypad/Display ID Parameter Name

Menu Name Item Name

Zone Heating



Occ Htg Spt= 70.0 °F Heating Enable Set Point

Htg Deadband= 1.0 °F Heating Enable Dead Band

OM-137-2 93

Morning Warm-up Control

On return air units, morning warm up operation occurs after the transition from unoccupied to occupied mode when the Ctrl Temp= value is below Effective Heating Enable Set Point by more than half the Heating Enable Dead Band. Under these conditions, the controller enters the MWU operating state after the normal startup sequence.


The MWU operating state is similar to the Heating state; the only difference is that the Eff Min OA Pos= parameter is set to 0% during MWU. The unit remains in the MWU operating state until either the Ctrl Temp= value is equal to or greater than the Effective Heating Enable Set Point or the duration of the MWU operating state exceeds the Maximum Morning Warm-up Timer setting. In either case, since the Ctrl Temp= value has not risen above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band when this occurs, the controller enters the Heating operating state.The Maximum Morning Warm-up Timer parameter is provided to ensure that the required minimum ventilation air is being supplied after a known time regardless of the space temperature condition. For example, if actual occupancy is at 8:00 a.m. and unit startup is scheduled for 6:30 a.m., a Maximum Morning Warm-up Timer setting of 90 minutes would ensure that the outdoor air dampers open to minimum position when building occupancy begins.

Note: The morning warm-up function does not occur on units equipped with 100% OA hoods.

High Ambient Heating Lockout

Heating is disabled when the outdoor air temperature is greater than the High Ambient Heating Lockout Set Point. When this occurs, the Htg Status= parameter in the System and Zone Heating menu indicates “Off Amb” if heating is not disabled for some other reason. When the outdoor air temperature drops below the High Ambient Heating Lockout Set Point by more than the High Ambient Heating Lockout Differential, heating operation is re-enabled.

Heating: MultistageTemperature Control

Entering Heating Operating StateThe unit enters the Heating operating state from the Fan Only operating state when the Ctrl Temp= value falls below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band, and the Disch Air= parameter is below the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead BandWhen the unit is in the Heating operating state, heating stages are turned on and off to maintain the discharge air temperature at the Effective Discharge Heating Set Point.

Note: Unless it is reset via one of the discharge air set point reset methods described in “Heating Dis-charge Set Point Reset” on page 103, the Effective



Menu Name Item Name

Zone Heating





Timer Settings Max MWU= 90 min Maximum Morning Warm-up Timer



Menu Name Item Name

Zone HeatingOATHtg Lock= 55.0 ºF High Ambient Heating

Lockout Set Point

OATLock Diff= 1.0 °F High Ambient Heating Lockout Differential



Menu Name Item Name

Zone HeatingEff Htg Spt= ____ °F Effective Heating

Enable Set Point


Discharge Heating

Eff Htg Spt= ___ °F Effective Discharge Heating Set Point

DAT Htg Spt= 55.0 ºF Discharge Heating Set Point

Htg Db= 1.0 ºF Discharge Heating Dead Band

Heating Setup Stage Time= 5 Min Heating Interstage Timer

94 OM-137-2

Discharge Heating Set Point is set by the controller equal to the Discharge Heating Set Point.

A heating stage change can only occur after the Heating Interstage Timer has expired and if the discharge air temperature is above or below the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead Band. When the discharge air temperature is below the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead Band and the Heating Interstage Timer has expired, the heating capacity is increased by one stage. When the discharge air temperature is above the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead Band and the Heating Interstage Timer has expired, the heating capacity is decrease by one stage.

Effective Discharge Heating Set Point Limiting. On units equipped with multistage electric heat, the Effective Discharge Heating Set Point is limited by a factory set 60°F maximum heater temperature rise limit. The controller does not allow the Effective Discharge Heating Set Point to be set higher than 60°F above the current temperature entering the discharge fan as indicated by the Ent Fan= parameter in the Temperatures menu.Heating to Fan Only Operating StateThe unit will transition from the Heating to Fan Only operating state when the Disch Air= parameter is above the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead Band and the heating capacity has been at 0% for longer than the Heating Interstage Timer period.The unit will also transition from the Heating to Fan Only operating state if the Ctrl Temp= parameter rises above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band.The unit will also transition from the Heating to Fan Only operating state if heating operation is disabled as described below in “High Ambient Heating Lockout” on page 96.


On return air units, morning warm up operation occurs after the transition from unoccupied to occupied mode when the Ctrl Temp= value is below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band. Under these conditions, the controller enters the MWU operating state after the normal startup sequence.


The MWU operating state is similar to the Heating state; the only difference is that the Eff Min OA Pos= parameter is set to 0% during MWU. The unit remains in the MWU operating state until either the Ctrl Temp= value is equal to or greater than the Effective Heating Enable Set Point or the duration of the MWU operating state exceeds the Maximum Morning Warm-up Timer setting. In either case, since the Ctrl Temp= value has not risen above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band when this occurs, the controller enters the Heating operating state.The Maximum Morning Warm-up Timer parameter is provided to ensure that the required minimum ventilation air is being supplied after a known time regardless of the space temperature condition. For example, if actual occupancy is at 8:00 a.m. and unit startup is scheduled for 6:30 a.m., a Maximum Morning Warm-up Timer setting of 90 minutes would ensure that the outdoor air dampers open to minimum position when building occupancy begins.




Menu Name Item Name

Zone Heating






OM-137-2 95


Heating is disabled when the outdoor air temperature is greater than the High Ambient Heating Lockout Set Point. When this occurs, the Htg Status= parameter in the System and Zone Heating menu indicates “Off Amb” (unless heating is disabled for some other reason). When the outdoor air temperature drops below the High Ambient Heating Lockout Set Point by more than the High Ambient Heating Lockout Differential, heating operation is re-enabled.

Discharge Air Low Limit Control

If heating is enabled and there is no heating load (normally Fan Only operating state), the controller activates the unit staged electric heating equipment as required to prevent the discharge air temperature from becoming too cool if the Min DAT Control Flag is set to “Yes.” If the discharge air temperature falls below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band, the unit operating state changes from Fan Only to Min DAT. Because there is no actual overall heating load, the VAV Box Output (MCB-BO12) remains closed (cool) during the Min DAT operating state. The closed VAV Box Output can be used to signal heat/cool VAV boxes that the unit is delivering air at the cooling set points. Except for controlling to the Effective Discharge Cooling Set Point, Min DAT temperature control is identical to the Heating operating state.The Min DAT operating state is very useful for applications requiring high minimum outdoor air amounts to satisfy indoor air quality requirements. If the outdoor air temperature is very cold, the discharge air temperature could become unacceptably cold in these units. Because the economizer dampers maintain their minimum position

during the Min DAT operating state, minimum ventilation requirements are not violated.

Heating: ModulatingTemperature Control

Entering Heating Operating StateThe unit enters the Heating operating state from the Fan Only operating state when the Ctrl Temp= value falls below the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band and the Disch Air= parameter is below the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead Band.When the unit is in the Heating operating state, heating capacity is modulated to maintain the discharge air temperature at the Effective Discharge Heating Set Point.

Note: Unless it is reset via one of the discharge air set point reset methods described in “Heating Dis-charge Set Point Reset” on page 103, the Effective Discharge Heating Set Point is set by the controller equal to the Discharge Heating Set Point.

There are several different modulating heating types available with this equipment. There are some differences in



Menu Name Item Name

Zone HeatingOATHtg Lock= 55.0 °F High Ambient Heating

Lockout Set Point




Menu Name Item Name

Discharge CoolingEff Clg Spt= 55.0 °F Effective Discharge

Cooling Set Point

Clg Db= 1.0 °F Discharge Cooling Dead Band

Discharge Heating Min DAT Ctrl= Yes Min DAT Control Flag



Menu Name Item Name

Zone HeatingEff Htg Spt= ___ °F Effective Heating

Enable Set Point

Htg Db= 1.0 °F Heating Enable Dead Band

Discharge Heating


DAT Htg Spt= 100 °F Discharge Heating Set Point

Htg Db= 1.0 °F Discharge Heating Dead Band

Min DAT Ctrl= Yes Min DAT Control Flag

Heating Setup

Stage Timer= 5 min Heating Interstage Timer

F&BP Ctrl= OpenValve Face and Bypass Method Flag

F&BP Chgovr= 37 °FFace and Bypass

Changeover Temperature

Htg Propbd= 30.0 °F Heating Proportional Band

Htg IntTime= 100 sec Heating Integral Time

Htg Period= 30 sec Heating Period

Discharge Cooling Eff Clg Spt= ___ °F Effective Discharge Cooling Set Point

96 OM-137-2

the control sequence depending on the heat type installed. The different types are described in the following sections.Steam or Hot Water Heat: Valve ControlWhen a unit equipped with steam or hot water heating is in the Heating operating state, the steam or hot water valve is modulated to maintain the discharge air temperature at the Effective Discharge Heating Set Point. The controller uses three PID control loop parameters to modulate the hot water or steam valve as the discharge air temperature changes. These are the Heating Proportional Band, Heating Integral Time and Heating Period. These parameters can be adjusted, but the factory default values provide the best control for most applications. For detailed information on tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.Steam or Hot Water Heat: Face and Bypass Damper ControlWhen a unit equipped with steam or hot water with face and bypass damper heating is in the Heating operating state, there are two methods available for controlling the heating arrangement. These are the “Open Valve” and “Modulating Valve” methods and are described in the following sections.

Open Valve Method. When the Face and Bypass Method Flag is set to “OpenValve” and the unit enters the Heating operating state, the steam or hot water valve is driven fully open. The face and bypass dampers are then modulated to maintain the discharge air temperature at the Effective Discharge Heating Set Point. The controller uses three PID control loop parameters to modulate the face and bypass dampers as the discharge air temperature changes. These are the Heating Proportional Band, Heating Integral Time and Heating Period. These parameters can be adjusted, but the factory default values provide the best control for most applications. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.

Modulating Valve Method. When the Face and Bypass Method Flag is set to “Mod Valve”, the steam or hot water valve is driven fully open when the unit enters the Heating operating state if the outdoor air temperature is below the Face and Bypass Changeover Temperature setting. The face and bypass dampers are then modulated to maintain the discharge air temperature at the Effective Discharge Heating Set Point. If the outdoor air temperature is above the Face and Bypass Changeover Temperature setting, the face and bypass dampers are driven fully open to the “face” when the unit enters the Heating operating state. The steam or hot water valve is then modulated to maintain the discharge air temperature at the Effective Discharge Heating Set Point. The controller uses three PID control loop parameters to modulate the heating valve or face and bypass dampers as the discharge air temperature changes. These are the Heating Proportional Band, Heating Integral Time and Heating Period. These parameters can be adjusted, but the factory

default values provide the best control for most applications. For detailed information on tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.Gas HeatWhen a unit is equipped with modulating gas heating and is in the Heating operating state, the gas valve is modulated to maintain the discharge air temperature at the Effective Discharge Heating Set Point. Differences in the control of modulating gas heat, particularly when the unit is equipped with a 100% OA hood, are described in the following sections.

Effective Discharge Heating Set Point Limiting. On units equipped with modulating gas heat, the Effective Discharge Heating Set Point is limited according to a maximum heat exchanger temperature rise limit. This factory set limit varies depending on the unit burner model and can be found on the gas heat data plate attached to the unit. The controller does not allow the Effective Discharge Heating Set Point to be set above the current temperature entering the discharge fan, as indicated by the Ent Fan= parameter in the Temperatures menu, by more than this maximum heat exchanger temperature rise limit.

Units with Return Air. When the unit enters the Heating operating state, the controller first holds the gas valve at the minimum fire position (5% or 33% depending on the burner model) until the Heating Interstage Timer expires. Then, the controller modulates the gas valve to maintain the discharge air temperature at the Effective Discharge Heating Set Point. The controller uses three PID control loop parameters to modulate the valve as the discharge air temperature changes. These are the Heating Proportional Band, Heating Integral Time and Heating Period. These parameters can be adjusted, but the factory default values provide the best control for most applications. For detailed information on tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.

100% OA Units. If a unit is equipped with a 100% OA hood and high-turndown (5%) modulating gas heat, and heat is required at unit startup, the furnace enters a special burner startup sequence as the unit enters its Startup operating state. Pre-firing the burner allows the gas heat pre-purge sequence to occur and the burner to fire and warm up so that tempered air is available immediately when the fans start. The special sequence occurs if the Heat Status= parameter in the System or Zone Heating menu indicates “Htg Ena” and either of the following conditions are true:1. The Ctrl Temp= value is below Effective Heating

Enable Set Point by more than half the Heating Enable Dead Band.

2. Min DAT Control Flag is set to “Yes” and the outdoor air temperature is below the Effective Discharge Cool-ing Set Point by more than half the Discharge Heating Dead Band.

OM-137-2 97

When the special gas heat startup sequence is activated upon entering the Startup operating state, the burner 90 pre-purge cycle is started at the same time as a four-minute timer. The burner starts and operates at the minimum fire position (5%) during this four-minute time period after the completion of the pre-purge cycle. When the four-minute timer expires, the burner variable orifice is modulated to a “preheat firing rate” according to the formula above, where:Preheat Firing Time is the time increment that the variable orifice “increase” output relay (MCB-BO10) is energized to achieve the “preheat firing rate.” Thirty seconds is the maximum.Variable Orifice Travel Time is the amount of time it takes the burner variable orifice to drive from the fully closed to fully open position (30 seconds-fixed).Applicable Discharge Air Temperature Set Point is either the Effective Discharge Heating Set Point or Effective Discharge Cooling Set Point. It is the Effective Discharge Heating Set Point if the Ctrl Temp= value is below Effective Heating Enable Set Point by more than half the Heating Enable Dead Band. It is the Effective Discharge Cooling Set Point if the Ctrl Temp= value is above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band, the Min DAT Control Flag is set to “Yes” and the outdoor air temperature is below the Effective Discharge Cooling Set Point by more than half the Discharge Heating Dead Band. Refer to “Discharge Air Low Limit Control” on page 99.Maximum Heat Exchanger Temperature Rise is the maximum temperature rise across the heat exchanger for safe operation. This number varies with burner model and the baffle position and is programmed into the controller at the factory. This value can be found on the gas heat data plate attached to the unit. Refer also to “Software Identification and Configuration” on page 129.Outdoor Air Temperature is the current outdoor air temperature input to the controller.Once modulated to the “preheat firing rate”, the burner remains at this rate for a fixed thirty second time period to allow the heat exchanger to warm-up before the unit leaves the Startup and enters the Heating operating state at which time the fans are started. After entering the Heating operating state, the burner remains at the “preheat firing rate” for a fixed four minute time period to allow the temperature to stabilize at this rate before “normal” gas heat control begins. When the unit enters the Heating operating state and “normal” gas heat control begins, the controller then modulates the gas valve to maintain the discharge air

temperature at the Effective Discharge Heating Set Point. The controller uses three PID control loop parameters to modulate the gas valve as the discharge air temperature changes. These are the Heating Proportional Band, Heating Integral Time and Heating Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.Heating to Fan Only Operating StateThe unit will transition from the Heating to Fan Only operating state when the Disch Air= parameter is above the Effective Discharge Heating Set Point by more than half the Discharge Heating Dead Band and the heating valve has been closed (or the face and bypass dampers have been closed to the face) for longer than the Heating Interstage Timer period.The unit will also transition from the Heating to Fan Only operating state if the Ctrl Temp= parameter rises above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band.The unit will also transition from the Heating to Fan Only operating state if heat operation is disabled as described in “High Ambient Heating Lockout” on page 99.


On return air units, morning warm up operation occurs after the transition from unoccupied to occupied mode when the Ctrl Temp= value is below Effective Heating Enable Set Point by more than half the Heating Enable Dead Band.

Preheat Firing Time Variable Orifice Travel Time Applicable Discharge Air Temperature Set Point Outdoor Air Temperature–Maximum Heat Exchanger Temperature Rise

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------×=



Menu Name Item Name

Zone Heating



Occ Htg Spt= 70.0 ºF Heating Enable Set Point



98 OM-137-2

Under these conditions, the controller enters the MWU operating state after the normal startup sequence.


The MWU operating state is similar to the Heating state; the only difference is that the Eff Min OA Pos= parameter is set to 0% during MWU. The unit remains in the MWU state until either the Ctrl Temp= value is equal to or greater than the Effective Heating Enable Set Point or the duration of the MWU state exceeds the Maximum Morning Warm-up Timer. In either case, since the Ctrl Temp= value has not risen above the Effective Heating Enable Set Point by more than half the Heating Enable Dead Band when this occurs, the controller enters the Heating operating state.The Maximum Morning Warm-up Timer parameter is provided to ensure that the required minimum ventilation air is being supplied after a known time regardless of the space temperature condition. For example, if actual occupancy is at 8:00 a.m. and unit startup is scheduled for 6:30 a.m., a Maximum Morning Warm-up Timer setting of 90 minutes would ensure that the outdoor air dampers open to minimum position when building occupancy begins.



Heating is disabled whenever the outdoor air temperature is greater than the High Ambient Heating Lockout Set Point. When this occurs, the Htg Status= parameter in the System and Zone Heating menu indicates “Off Amb” if heating is not disabled for some other reason. When the outdoor air

temperature drops below the High Ambient Heating Lockout Set Point by more than the High Ambient Heating Lockout Differential, heating operation is re-enabled.

Discharge Air Low Limit Control

If heating is enabled and there is no heating load (normally Fan Only state), the controller activates the unit modulating heating equipment as required to prevent the discharge air temperature from becoming too cool if the Min DAT Control Flag is set to “Yes.” If the discharge air temperature falls below the Effective Discharge Cooling Set Point by more than half the Discharge Cooling Dead Band, the unit operating state changes from Fan Only to Min DAT. Because there is no actual overall heating load, the VAV Box Output (MCB-BO12) remains closed (cool) during the Min DAT state. The closed VAV Box Output can be used to signal heat/cool VAV boxes that the unit is delivering air at the cooling set points. Except for controlling to the Effective Discharge Cooling Set Point rather than the Effective Discharge Heating Set Point, Min DAT temperature control is identical to that for the Heating state.The Min DAT operating state is very useful for applications that require large amounts of minimum outdoor air to accommodate indoor air quality requirements. If the outdoor air temperature is very cold, the discharge air temperature could otherwise become unacceptably cold in these units. Because the economizer dampers maintain their minimum position during the Min DAT state, minimum ventilation requirements are not violated.



Menu Name Item Name

Zone HeatingOATHtg Lock= 55.0 ºF High Ambient Heating

Lockout Set Point




Menu Name Item Name

Discharge CoolingEff Clg Spt= 55.0 ºF Effective Discharge

Cooling Set Point


Discharge Heating Min DAT Ctrl= Yes Min DAT Control Flag

OM-137-2 99

Discharge Set Point ResetCooling Discharge Set Point Reset

By automatically varying the discharge air temperature to suit the cooling load, discharge air temperature reset can make discharge air control systems more energy efficient. A variety of reset strategies are available (some require field wiring). The Effective Discharge Cooling Set Point can be reset between the Minimum Discharge Cooling Set Point and Maximum Discharge Cooling Set Point in a number of ways. These are described as follows:No Discharge Temperature ResetWhen the Cooling Reset Type Flag is set to “None”, the Effective Discharge Cooling Set Point is set equal to the Discharge Cooling Set Point.Temperature Based Discharge Temperature ResetThe Effective Discharge Cooling Set Point can be reset in response to three temperature sensor inputs: space, return air, or outdoor air. When any of these methods are used, the Effective Discharge Cooling Set Point is determined based on the selected temperature sensor input.When the Cooling Reset Type Flag is set to “Space”, the Effective Discharge Cooling Set Point is reset based on the current space air temperature input. The space temperature

sensor is optional and must be present to allow for reset based on space temperature.

Note: The Cooling Reset Type Flag reverts to “None” if the Space Sensor problem occurs or if the Space Sensor= parameter in the Unit Configuration menu is set to “No”.

When the Cooling Reset Type Flag is set to “Return”, the Effective Discharge Cooling Set Point is reset based on the current return air temperature input.

Note: A unit equipped with the 100% OA hood option does not have a return air temperature sensor and, therefore, “Return” cannot be selected.

When the Cooling Reset Type Flag is set to “OAT”, the Effective Discharge Cooling Set Point is reset based on the current outdoor air temperature input.

Note: The Cooling Reset Type Flag reverts to “None” if the OAT Sensor problem occurs.

An example of discharge temperature reset based on outdoor air temperature is illustrated in Figure 11 on page 101 (Cooling Reset Type Flag is set to “OAT” in this example). When the current outdoor air temperature is greater than or equal to the Minimum Cooling Set Point Reset Value (90°F in this example), the Effective Discharge Cooling Set Point is set equal to the Minimum Discharge Cooling Set Point (55°F in this example). This is shown as Point C in Figure 11. When the current outdoor air temperature is less than or equal to the Maximum Cooling Set Point Reset Value (70°F in this example), the Effective Discharge Cooling Set Point is set equal to the Maximum Discharge Cooling Set Point (65 °F in this example). This is shown as Point A in Figure 11. When the current outdoor air temperature is between the Minimum Cooling Set Point Reset Value and the Maximum Cooling Set Point Reset Value, the Effective Discharge Cooling Set Point varies linearly between the Minimum Discharge Cooling Set Point and Maximum Discharge Cooling Set Point. This is shown as Point B in Figure 11.

Note: The Minimum Cooling Set Point Reset Value and Maximum Cooling Set Point Reset Value are dis-played on the keypad/display without engineering units. The values represent temperature (°F or °C) when the Cooling Reset Type Flag is set to “Space”, “Return”, or “OAT.” The values represent percent-age (%) when the Cooling Reset Type Flag is set to “Ext mA”, “Ext V” or “Airflow.”



Menu Name Item Name

Discharge Cooling

Eff Clg Spt= ___ °F Effective Discharge Cooling Set Point

DA Clg Spt= 55.0 °F Discharge Cooling Set Point

Min Clg Spt= 55.0 °F Minimum Discharge Cooling Set Point

Max Clg Spt= 65.0 °F Maximum Discharge Cooling Set Point

Clg Reset= None Cooling Reset Type Flag

Min Clg Spt@= 90 Minimum Cooling Set Point Reset Value

Max Clg Spt@= 70 Maximum Cooling Set Point Reset Value

100 OM-137-2

Figure 11: Discharge Temperature Reset Based on Temperature

Airflow Based Discharge Temperature ResetThe Effective Discharge Cooling Set Point can be reset based on the discharge fan airflow capacity. Discharge fan capacity reset is used when the Cooling Reset Type Flag is set to “Airflow.”An example of discharge temperature reset based on airflow is illustrated in Figure 12. When the discharge fan capacity is greater than or equal to the Minimum Cooling Set Point Reset Value (100% in this example), the Effective Discharge Cooling Set Point is set equal to the Minimum Discharge Cooling Set Point. This is shown as Point C in Figure 12. When the discharge fan capacity is less than or equal to the Maximum Cooling Set Point Reset Value (30% in this example), the Effective Discharge Cooling Set Point is set equal to the Maximum Discharge Cooling Set Point. This is

shown as Point A in Figure 12. When the discharge fan capacity is between the Minimum Cooling Set Point Reset Value and the Maximum Cooling Set Point Reset Value, the Effective Discharge Cooling Set Point varies linearly between the Minimum Discharge Cooling Set Point and Maximum Discharge Cooling Set Point. This is shown as Point B in Figure 12.

Note: The Minimum Cooling Set Point Reset Value and Maximum Cooling Set Point Reset Value are dis-played on the keypad/display without engineering units. The values represent temperature (°F or °C) when the Cooling Reset Type Flag is set to “Space”, “Return” or “OAT.” The values represent percent-age (%) when the Cooling Reset Type Flag is set to “Ext mA”, “Ext V” or “Airflow.”

Figure 12: Discharge Temperature Reset Based on Discharge Fan Airflow

A

B

C

Maximum DischargeCooling Set Point = 65°F

60°F

Minimum DischargeCooling Set Point = 55°F

Minimum CoolingSet Point ResetValue

Maximum CoolingSet Point Reset

Value

60 70 80 90 100

OA Temperature (°F)

Eff

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A

B

C

MaximumDischargeCooling Set Point = 65°F

60°F

Minimum DischargeCooling Set Point = 55°F

Minimum CoolingSet Point ResetValue


Value

30 65 100

Discharge Fan Capacity (%)

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OM-137-2 101

External Discharge Temperature ResetThe Effective Discharge Cooling Set Point can be reset based on a field supplied analog voltage or current signal. This signal can be in the range of 0-10 VDC or 0-20 mA. When the Cooling Reset Type Flag is set to “Ext V” or “Ext mA”, the Effective Discharge Cooling Set Point varies linearly between the Minimum Discharge Cooling Set Point and the Maximum Discharge Cooling Set Point as the field voltage or current signal varies between a minimum and maximum (or maximum and minimum) value.The range and type of field reset signal is configured using the Minimum Cooling Set Point Reset Value and the Maximum Cooling Set Point Reset Value and setting a jumper on the main control board associated with analog input MCB-AI02. The analog input jumper is placed in either the “voltage” or “current” position. When it is in the “voltage” position, the range of the input signal can be from 0-10 VDC and when in the “current” position, 0-20 mA. The input range is scaled using the Minimum Cooling Set Point Reset Value and the Maximum Cooling Set Point Reset Value parameters. If for example, the field signal is to be 1-5 VDC, the Minimum Cooling Set Point Reset Value must be set to 10 (10%) since 1 VDC is 10% of the 0-10 VDC range. The Maximum Cooling Set Point Reset Value must be set to 50 (50%) since 5 VDC is 50% of the 0-10 VDC range.Refer to “External Discharge Air Reset Signal” in the “Field Wiring” section of IM 696, MicroTech Applied Rooftop Unit Controller.Reset based on an external signal can be “direct acting” where the Effective Discharge Cooling Set Point increases as the field signal increases or it can be “reverse acting” where the Effective Discharge Cooling Set Point decreases as the field signal increases. The following are examples of both “direct acting” and “reverse acting” reset.An example of “direct acting” discharge temperature reset based on an external 1- 5 VDC signal is illustrated in Figure 13. When the external voltage signal is less than or equal to the Minimum Cooling Set Point Reset Value (10% or 1 VDC in this example), the Effective Discharge Cooling Set Point is set equal to the Minimum Discharge Cooling Set Point (55 °F in this example). This is shown as Point A in Figure 13. When the external voltage signal is greater than or equal to the Maximum Cooling Set Point Reset Value (50% or 5 VDC in this example), the Effective Discharge Cooling Set Point is set equal to the Maximum Discharge Cooling Set Point (65 °F in this example). This is shown as Point C in Figure 13. When the external voltage signal is between the Minimum Cooling Set Point Reset Value and the Maximum Cooling Set Point Reset Value, the Effective Discharge Cooling Set Point increases linearly between the Minimum

Discharge Cooling Set Point and Maximum Discharge Cooling Set Point. This is shown as Point B in Figure 13.

Note: If the field signal exceeds 10VDC, the Cooling Reset Type Flag reverts to “None” and set point reset is disabled.

Figure 13: Direct Acting External Reset

An example of “reverse acting” discharge temperature reset based on an external 1- 5 VDC signal is illustrated in Figure 14. When the external voltage signal is less than or equal to the Maximum Cooling Set Point Reset Value (10% or 1 VDC in this example), the Effective Discharge Cooling Set Point is set equal to the Maximum Discharge Cooling Set Point (65°F in this example). This is shown as Point A in Figure 14. When the external voltage signal is greater than or equal to the Minimum Cooling Set Point Reset Value (50% or 5 VDC in this example), the Effective Discharge Cooling Set Point is set equal to the Minimum Discharge Cooling Set Point (55°F in this example). This is shown as Point C in Figure 14. When the external voltage signal is between the Maximum Cooling Set Point Reset Value and the Minimum Cooling Set Point Reset Value, the Effective Discharge Cooling Set Point decreases linearly between the Maximum Discharge Cooling Set Point and Minimum Discharge Cooling Set Point. This is shown as Point B in Figure 14.

Note: The Minimum Cooling Set Point Reset Value and Maximum Cooling Set Point Reset Value are dis-played on the keypad/display without engineering units. The values represent temperature (°F or °C) when the Cooling Reset Type Flag is set to “Space”, “Return” or “OAT.” The values represent percent-age (%) when the Cooling Reset Type Flag is set to “Ext mA”, “Ext V” or “Airflow.”

MinimumDischarge

Cooling SetPoint = 55°F

60°F

A

B

CMaximumDischargeCooling SetPoint = 65°F

Minimum CoolingSet Point Reset

Value (10%)

Maximum CoolingSet Point ResetValue (50%)

1 3 5

External Signal (Vdc)

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102 OM-137-2

Figure 14: Reverse Acting External Reset

Network Discharge Temperature ResetWhen the Cooling Reset Type Flag is set to “None”, the Effective Discharge Cooling Set Point is set equal to the Discharge Cooling Set Point. The Discharge Cooling Set Point can then be set via a network signal to meet the discharge air temperature requirements.

Heating Discharge Set Point Reset

The heating discharge set point can be reset in all heating configurations except “One Stage” or “No Heat.” By automatically varying the discharge air temperature to suit the heating load, discharge air temperature reset can make discharge air control systems more energy efficient. A

variety of reset strategies are available (some require field wiring). The Effective Discharge Heating Set Point can be reset between the Minimum Discharge Heating Set Point and Maximum Discharge Heating Set Point in a number of ways.

Note: On units equipped with modulating gas heat, the Effective Discharge Heating Set Point is limited according to a maximum heat exchanger tempera-ture rise limit. This factory set limit varies depend-ing on the heater model and can be found on the heater data plate attached to the unit. The controller does not allow the Effective Discharge Heating Set Point to be set above the current temperature enter-ing the discharge fan, as indicated by the Ent Fan= parameter in the Temperatures menu, by more than this maximum heat exchanger temperature rise limit

No Discharge Temperature ResetWhen the Heating Reset Type Flag is set to “None”, the Effective Discharge Heating Set Point is set equal to the Discharge Heating Set Point.Temperature Based Discharge Temperature ResetThe Effective Discharge Heating Set Point can be reset in response to three temperature sensor inputs: space, return air, or outdoor air. When any of these methods are used, the Effective Discharge Heating Set Point is determined based on the selected temperature sensor input.When the Heating Reset Type Flag is set to “Space”, the Effective Discharge Heating Set Point is reset based on the current space air temperature input. The space temperature sensor is optional and must be present to allow for reset based on space temperature.

Note: The Heating Reset Type Flag reverts to “None” if the Space Sensor problem occurs or if the Space Sensor= parameter in the Unit Configuration menu is set to “No”.

When the Heating Reset Type Flag is set to “Return”, the Effective Discharge Heating Set Point is reset based on the current return air temperature input.

Note: A unit equipped with the 100% OA hood option does not have a return air temperature sensor and, therefore, “Return” cannot be selected.

When the Heating Reset Type Flag is set to “OAT”, the Effective Discharge Heating Set Point is reset based on the current outdoor air temperature input.

Note: The Heating Reset Type Flag reverts to “None” if the OAT Sensor problem occurs.



Menu Name Item Name

Discharge Heating


DA Htg Spt= 100.0 ºF Discharge Heating Set Point

Min Htg Spt= 60.0 ºF Minimum Discharge Heating Set Point

Max Htg Spt= 120.0 ºF Maximum Discharge Heating Set Point

Htg Reset= None Heating Reset Type Flag

Min Htg Spt@= 60.0 Minimum Heating Set Point Reset Value

Max Htg Spt@= 20.0 Maximum Heating Set Point Reset Value

MinimumDischargeCooling SetPoint = 55°F

60°F

A

B

C

MaximumDischarge

Cooling SetPoint = 65°F

Minimum CoolingSet Point ResetValue (50%)


Value (10%)

1 3 5


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OM-137-2 103

Figure 15: Discharge Temperature Reset Based on Temperature

An example of discharge temperature reset based on outdoor air temperature is illustrated in Figure 15 (Heating Reset Type Flag is set to “OAT” in this example). When the current outdoor air temperature is greater than or equal to the Minimum Heating Set Point Reset Value (60°F in this example), the Effective Discharge Heating Set Point is set equal to the Minimum Discharge Heating Set Point (60°F in this example). This is shown as Point C in Figure 15. When the current outdoor air temperature is less than or equal to the Maximum Heating Set Point Reset Value (20°F in this example), the Effective Discharge Heating Set Point is set equal to the Maximum Discharge Heating Set Point (120°F in this example). This is shown as Point A in Figure 15. When the current outdoor air temperature is between the Minimum Heating Set Point Reset Value and the Maximum Heating Set Point Reset Value, the Effective Discharge Heating Set Point increases linearly between the Minimum Discharge Heating Set Point and Maximum Discharge Heating Set Point. This is shown as Point B in Figure 15.

Note: The Minimum Heating Set Point Reset Value and Maximum Heating Set Point Reset Value are dis-played on the keypad/display without engineering units. The values represent temperature (°F or °C) when the Heating Reset Type Flag is set to “Space”, “Return” or “OAT.” The values represent percent-age (%) when the Heating Reset Type Flag is set to “Ext mA” or “Ext V.”

External Discharge Temperature ResetThe Effective Discharge Heating Set Point can be reset based on a field supplied analog voltage or current signal. This signal can be in the range of 0-10 VDC or 0-20 mA. When the Heating Reset Type Flag is set to “Ext V” or “Ext mA”, the Effective Discharge Heating Set Point varies linearly between the Minimum Discharge Heating Set Point and the Maximum Discharge Heating Set Point as the field

voltage or current signal varies between a minimum and maximum (or maximum and minimum) value.The range and type of field reset signal is configured using the Minimum Heating Set Point Reset Value and the Maximum Heating Set Point Reset Value and setting a jumper on the main control board associated with analog input MCB-AI02. The analog input jumper is placed in either the “voltage” or “current” position. When the jumper is in the “voltage” position, the range of the input signal can be from 0-10 VDC and when in the “current” position, 0-20 mA. The input range is scaled using the Minimum Heating Set Point Reset Value and the Maximum Heating Set Point Reset Value parameters. If for example, the field signal is to be 1-5 VDC, the Minimum Heating Set Point Reset Value must be set to 10 (10%) since 1 VDC is 10% of the 0-10 VDC range. The Maximum Heating Set Point Reset Value must be set to 50 (50%) since 5 VDC is 50% of the 0-10 VDC range.Refer to “External Discharge Air Reset Signal” in the “Field Wiring” section of IM 696, MicroTech II Applied Rooftop Unit Controller.Reset based on an external signal can be “direct acting” where the Effective Discharge Heating Set Point increases as the field signal increases or it can be “reverse acting” where the Effective Discharge Heating Set Point decreases as the field signal increases. The following are examples of both “direct acting” and “reverse acting” reset.An example of “direct acting” discharge temperature reset based on an external 1- 5 VDC signal is illustrated in Figure 16. When the external voltage signal is less than or equal to the Minimum Heating Set Point Reset Value (1 VDC in this example), the Effective Discharge Heating Set Point is set equal to the Minimum Discharge Heating Set Point (60°F in this example). This is shown as Point A Figure 16. When the external voltage signal is greater than or equal to the Maximum Heating Set Point Reset Value (5

A

B

C

Maximum DischargeHeating Set Point = 120°F

90°F

Minimum DischargeHeating Set Point = 60°F

Minimum HeatingSet Point ResetValue

Maximum HeatingSet Point Reset

Value

0 20 40 60 80

OA Temperature (°F)

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104 OM-137-2

VDC in this example), the Effective Discharge Heating Set Point is set equal to the Maximum Discharge Heating Set Point (120°F in this example). This is shown as Point C in Figure 16. When the external voltage signal is between the Minimum Heating Set Point Reset Value and the Maximum Heating Set Point Reset Value, the Effective Discharge Heating Set Point increases linearly between the Minimum Discharge Heating Set Point and Maximum Discharge Heating Set Point. This is shown as Point B in Figure 16.

Figure 16: Direct Acting External Reset

An example of “reverse acting” discharge temperature reset based on an external 1- 5 VDC signal is illustrated in Figure 17. When the external voltage signal is less than or equal to the Maximum Heating Set Point Reset Value (10% or 1 VDC in this example), the Effective Discharge Heating Set Point is set equal to the Maximum Discharge Heating Set Point (120°F in this example). This is shown as Point A Figure 17. When the external voltage signal is greater than or equal to the Minimum Heating Set Point Reset Value (50% or 5 VDC in this example), the Effective Discharge Heating Set Point is set equal to the Minimum Discharge Heating Set Point (60°F in this example). This is shown as Point C in Figure 17. When the external voltage signal is between the Maximum Heating Set Point Reset Value and the Minimum Heating Set Point Reset Value, the Effective Discharge Heating Set Point decreases linearly between the Maximum Discharge Heating Set Point and Minimum Discharge Heating Set Point. This is shown as Point B in Figure 17.

Note: The Minimum Heating Set Point Reset Value and Maximum Heating Set Point Reset Value are dis-played on the keypad/display without engineering units. The values represent temperature (°F or °C) when the Heating Reset Type Flag is set to “Space”,

“Return” or “OAT.” The values represent percent-age (%) when the Heating Reset Type Flag is set to “Ext mA”, “Ext V” or “Airflow.”

Note: If the field signal exceeds 10VDC, the Cooling Reset Type Flag reverts to “None” and set point reset is disabled.

Figure 17: Reverse Acting External Reset

Network Discharge Temperature ResetWhen the Heating Reset Type Flag is set to “None”, the Effective Discharge Heating Set Point is set equal to the Discharge Heating Set Point. The Discharge Heating Set Point can then be set via a network signal to meet the discharge air temperature requirements.

Energy Recovery When a unit is equipped with an optional energy recovery wheel, energy recovery is provided by drawing outside air across half of an enthalpy wheel and drawing exhaust air across the other half. Latent and sensible heat is transferred from the hotter moist exhaust air to the colder dry outside air in winter. Latent and sensible heat is transferred from the hotter moist outside air to the cooler dry exhaust air in summer. Energy recovery control consists of starting and stopping an exhaust fan, modulating the speed of the exhaust fan, starting and stopping an enthalpy wheel, optionally controlling the speed of the enthalpy wheel and opening and closing a set of bypass dampers. The outdoor dampers are controlled in the normal manner. Refer to “100% Outdoor Air Damper Control” on page 77 or “Economizer” on page 78 as applicable. The following sections describe the control of the enthalpy wheel, exhaust fan and bypass dampers.

MinimumDischarge

Heating SetPoint = 60°F

90°F

A

B

CMaximumDischargeHeating SetPoint = 120°F

Minimum HeatingSet Point Reset

Value (10%)

Maximum HeatingSet Point ResetValue (50%)

1 3 5


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MinimumDischargeHeating SetPoint = 60°F

90°F

A

B

C

MaximumDischarge

Heating SetPoint = 120°F

Minimum HeatingSet Point ResetValue (50%)

Maximum HeatingSet Point Reset

Value (10%)

1 3 5


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OM-137-2 105

Enthalpy Wheel Control

When the Energy Recovery Control Flag is set to “Yes”, the enthalpy wheel is turned on whenever the unit exhaust fan is on and the current OA Damper Pos= parameter in the OA Damper menu indicates a value within 3% of the Effective Minimum Outdoor Damper Position Set Point. It is turned off when the exhaust fan is turned off or the OA Damper Pos= value is greater than the Effective Minimum Outdoor Damper Position Set Point by more than 3% (as when the unit is in the Econo operating state).Constant Speed Enthalpy WheelWhen the unit is equipped with a constant speed enthalpy wheel, the wheel is driven to maximum speed whenever the enthalpy wheel is on.Variable Speed Enthalpy WheelWhen the unit is equipped with the energy wheel frost protection option, it has a variable speed enthalpy wheel. The wheel is driven to maximum speed whenever the enthalpy wheel is on. The speed of the wheel may be modulated as described below to prevent wheel frosting.When there is a threat of frost on the enthalpy wheel, the wheel is slowed down or stopped so that less enthalpy transfer occurs and frosting of the wheel is avoided. Frosting can occur on the enthalpy wheel when the exhaust air leaving the wheel is saturated. This condition occurs when two lines intersect on a psychometric chart, and it does not occur when these two lines do not intersect. One of these lines is the Humidity Ratio versus the dry bulb temperature for saturated air. The other line is the exhaust air process line. The exhaust air process is defined by two points on a psychometric chart. The first point on this line is the outdoor air temperature at 95% relative humidity (point 1 in Figure 18) and the second point on the line is the return air temperature at the return air relative humidity (point 2 in Figure 18). One exhaust air process line showing frosting conditions and another showing no frost conditions is shown

in Figure 18. The controller makes a continuous calculation to determine if and at what temperatures the saturated air and exhaust air process lines intersect. When they do not intersect, the enthalpy wheel runs at full speed. When they do intersect, the enthalpy wheel is controlled to a slower speed to maintain the dry bulb temperature of the exhaust air leaving the enthalpy wheel above the higher of the two intersecting dry bulb temperatures (point ST2 in Figure 18). This is referred to as the “Intersection Point”. This prevents the wheel from operating under frosting conditions.The following describes the details involved in the frost protection function that affect the speed and start/stop of the enthalpy wheel.When the enthalpy wheel has been operating at maximum speed for at least the Enthalpy Wheel Stage Time and the exhaust air temperature leaving the wheel (ER ExhT=) drops below the Intersection Point plus the Minimum Temperature Difference, the enthalpy wheel will be slowed to its minimum speed.If the enthalpy wheel has been operating at minimum speed for at least the Enthalpy Wheel Stage Time and the exhaust air temperature leaving the wheel (ER ExhT=) is still below the Intersection Point plus the Minimum Temperature Difference, the enthalpy wheel will be stopped.If the exhaust air temperature leaving the wheel (ER ExhT=) then rises above the Intersection Point plus the Maximum Temperature Difference and the enthalpy wheel has been off for longer than the Enthalpy Wheel Minimum Off Time, the wheel will be restarted and will run at its minimum speed.If the enthalpy wheel has been at minimum speed for longer than the Enthalpy Wheel Stage Time and the exhaust air temperature leaving the wheel (ER ExhT=) is still above the Intersection Point plus the Maximum Temperature Difference the wheel will be increased to its maximum speed.

Figure 18: Variable Speed Enthalpy Wheel Frost Protection - Psychometric Chart



Menu Name Item Name

OA Damper Eff Min OA Pos= ___%Effective Minimum Outdoor Damper Position Set Point

Energy Recovery Energy Rec= No Energy Recovery

Control Flag

Energy Rec Setup

Min ExhT Diff= 2°F Minimum Temperature Difference

Max ExhT Diff= 6°F Maximum Temperature Difference

Stage Time= 5 min Enthalpy Wheel Stage Time

Min Off Time= 20 min Enthalpy Wheel Minimum Off Time

Saturated Air

Enthalpy WheelExhaust Air(FrostConditions)

Enthalpy WheelExhaust Air (NoFrost Conditions)

Saturated Air

ST1

1

ST2

2

2SaturationTemperature

Hum

idity

Rat

ion

Dry Bulb Temperature

(Intersection Point)

106 OM-137-2

Exhaust Fan Control

Building Pressure ControlWhen the unit is equipped with a 0 - 100% modulating economizer or is 100% OA with a variable capacity discharge fan, the energy recovery option includes a variable capacity exhaust fan equipped with either a VFD or variable inlet vanes. When the Energy Recovery Control Flag is set to “Yes”, the Return/Exhaust Fan Capacity Control Flag is set to “BldgPres” and the Second Pressure Sensor Present Flag is set to “Bldg”, the exhaust fan is controlled based on the building static pressure. The exhaust fan is turned on when the discharge fan is running and the Bldg Press= parameter value is above the Building Static Pressure Set Point high by more than half the Building Static Pressure Dead Band for longer than the Minimum Exhaust Fan Off Timer.

Note: If the unit is 100% OA with a constant volume dis-charge fan, the exhaust fan is turned on whenever the outdoor air dampers are open.

The exhaust fan remains on until either of the following occur:

1. The Bldg Press= parameter value drops below the Building Static Pressure Set Point by more than half the Building Static Pressure Deadband and the RF/EF Fan Cap= value has been at the Exhaust Fan Minimum Capacity Value for longer than the Minimum Exhaust Fan On Timer.

2. The discharge fan is turned off.When the exhaust fan is on, its capacity is modulated to maintain the Bldg Press= parameter value at the Building Static Pressure Set Point using three PID control loop parameters. These are the Building Static Pressure Proportional Band, Building Static Pressure Integral Time and Building Static Pressure Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.Direct Position ControlWhen the unit is equipped with a 0 - 100% modulating economizer or is 100% OA with a variable capacity discharge fan, the energy recovery option includes a variable capacity exhaust fan equipped with either a VFD or variable inlet vanes. When the Energy Recovery Control Flag is set to “Yes” and the Return/Exhaust Fan Capacity Control Flag is set to “Position”, the exhaust fan is controlled based on Remote Return/Exhaust Fan Capacity Set Point. This set point can be adjusted via network signal. The exhaust fan is turned on when the the discharge fan is running and the exhaust fan capacity is commanded above the Exhaust Fan Minimum Capacity Value for longer than the Minimum Exhaust Fan Off Timer. The exhaust fan remains on until either of the following occur:1. The Remote Return/Exhaust Fan Capacity Set Point is

commanded to the Exhaust Fan Minimum Capacity Value for longer than the Minimum Exhaust Fan On Timer.

2. The discharge fan is turned off

Note: If the unit is 100% OA with a constant volume dis-charge fan, the exhaust fan is turned on whenever the outdoor air dampers are open.

Energy Recovery Bypass Damper Control

When a unit is equipped with a 0-100% modulating economizer, the energy recovery option includes a set of



Menu Name Item Name

Bldg PressureBldgSP Spt= 1.00 “WC Building Static

Pressure Set Point

BSP Db= 0.080 “WC Building Static Pressure Dead Band

OA Damper Eff Min OA Pos=___%Effective Minimum Outdoor Damper Position Set Point

Building Static P Setup

BSP Propbd= 0.400 “WCBuilding Static

Pressure Proportional Band

BSP IntTime= 2.0 secBuilding Static

Pressure Integral Time

BSP Period= 2.0 sec Building Static Pressure Period

Energy Recovery

EF Min Cap= 5%Exhaust Fan

Minimum Capacity Value

Energy Rec= No Energy Recovery Control Flag

Min Exh On= 120 sec Minimum Exhaust Fan On Timer

Min Exh Off= 120 sec Minimum Exhaust Fan Off Timer

Unit Configuration


RF/EF Ctrl= Tracking Return/Exhaust Fan Capacity Control Flag

Rem RF/EF Cap= 25%Remote

Return/Exhaust Fan Capacity Set Point



Menu Name Item Name

OA Damper Eff MinOA Pos= ___%Effective Minimum Outdoor Damper Position Set Point

OM-137-2 107

bypass dampers that allow air to bypass the energy recovery wheel when the wheel is not operating. The dampers are driven closed for 2 minutes whenever the energy recovery wheel is turned on, forcing the entering and leaving air to go through the wheel. When the outdoor dampers are driven more than 3% above the Effective Minimum Outdoor Damper Position Set Point (as when the unit enters the Economizer operating state) the wheel is shut off and the bypass dampers are driven open for 2 minutes allowing the entering and leaving air to bypass the wheel.

Discharge Fan Capacity ControlWhen a unit is equipped with discharge fan inlet guide vanes or a discharge fan VFD, there are two optional methods for controlling the discharge fan airflow. These are duct static pressure control and position control. The following sections describe the two methods.

Duct Static Pressure Control

When the Discharge Fan Capacity Control Flag is set to “DuctPres”, the controller modulates the discharge fan capacity as required to maintain the Duct Static Pressure Set Point. To do this it uses three PID control loop parameters to modulate the discharge inlet vane position or VFD speed as the duct static pressure changes. These are Duct Static Pressure Proportional Band, Duct Static Pressure Integral Time, and Duct Static Pressure Period. Although these parameters can be adjusted, for most applications, the factory default values provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.Duct static pressure control of the discharge air fan airflow is overridden under three conditions:1. The first condition is at unit startup. The discharge air-

flow is held at minimum speed (17% for inlet vanes,

25% for VFDs) for the first thirty seconds of the Recirc operating state.

2. The second condition is when “post heat” operation is active. Refer to “Post Heat Operation“. Discharge airflow is reduced to minimum during “Post Heat” operation.

3. The third condition is when the discharge inlet vanes modulate down to 17% or the VFD speed is reduced to 25%. The controller does not allow the capacity to mod-ulate below these fixed values.

Two Duct Static Pressure SensorsWhen a unit is equipped with discharge fan inlet guide vanes or a discharge fan VFD, a second duct static pressure sensor is optional. If a second duct static pressure sensor (SPS2) is connected, the Second Pressure Sensor Present Flag can be set to “Duct.” The controller then automatically selects the lower of the two sensed pressures and uses this value to control discharge fan airflow (the Duct Press= parameter indicates the lower of the two readings). On larger buildings, this strategy can be used to assure that adequate static pressure is available throughout the VAV system.

Note: If a second duct sensor is not installed, the Second Pressure Sensor Present Flag must not be set to “Duct.”

Discharge Fan Direct Position Control

When a unit is equipped with discharge fan inlet guide vanes or a discharge fan VFD, the inlet guide vane position or VFD speed can be controlled to a specific position set point based on a network signal. When the Discharge Fan Capacity Control Flag is set to “Position”, the controller positions the discharge fan inlet vanes or VFD speed to the Remote Discharge Fan Capacity Set Point. Normal duct static pressure control is overridden in this case. If network communications is interrupted or is not present, the Remote Discharge Fan Capacity Set Point remains at the last commanded setting and then can be adjusted via the unit keypad/display. The Remote Discharge Fan Capacity Set Point can be adjusted from the fixed minimum (17% for vanes or 25% for VFD applications) to 100%. When the Discharge Fan Capacity Control Flag is set to “DuctPres”, the Remote Discharge Fan Capacity Set Point has no effect on the unit operation.



Menu Name Item Name

Duct Pressure

DuctSP Spt= 1.00 “WC

Duct Static Pressure Set Point

DSP Db= 0.080 “WC Duct Static Pressure Dead Band

Duct Static P Setup

DSP Propbd= 6.0 “WC

Duct Static Pressure Proportional Band

DSP IntTime= 12 sec Duct Static Pressure Integral Time

DSP Period= 10 sec Duct Static Pressure Period

Unit Configuration2nd P Sensor= None Second Pressure

Sensor Present Flag

DF CapCtrl= DuctPres

Discharge Fan Capacity Control Flag



Menu Name Item Name

Unit Configuration

DF CapCtrl= DuctPresDischarge Fan


Remote DF Cap= 25%Remote Discharge Fan Capacity Set

Point

108 OM-137-2

Post Heat Operation

After leaving the Recirc or Heating operating state and entering either the Fan Only or Min DAT operating state, the unit performs “post heat” operation if the Post Heat Timer is set to a non zero value. “Post heat” operation occurs within the Fan Only or MinDAT operating state. During “post heat” operation, the VAV Box Output (MCB-B012) remains open (heat) while the discharge fan capacity is forced to a minimum value (17% position for inlet vanes, 25% speed for VFD). By forcing the discharge fan capacity to a minimum value before the VAV Box Output (MCB-B012) closes (cool), “post heat” operation is designed to prevent duct over-pressurization by decreasing the duct pressure before the VAV boxes can close. For detailed information regarding the VAV Box Output, refer to the “Field Wiring” section of IM696, MicroTech II Applied Rooftop Unit Controller.“Post heat” operation remains active until either the discharge fan capacity reaches the minimum value or until the Post Heat Timer expires, whichever occurs first. When “post heat” operation ends, normal duct static pressure or position control resumes.

Note: During “post heat” operation and for 120 seconds afterward, the proof of airflow input is ignored. This is to prevent nuisance Fan Fail fault alarms that may occur if the airflow switch opens during or following “post heat” operation. The unit cannot leave the Fan Only or Min DAT operating state while the airflow switch input is being ignored.

Return Fan Capacity ControlWhen a unit is equipped with return fan inlet guide vanes or a return fan VFD, there are three optional methods for controlling the return fan capacity. These are “fan tracking” control, “direct building static pressure” control and “position” control. The following sections describe the three methods.

VaneTrol Fan Tracking Control

When a unit is equipped with both discharge and return fan inlet guide vanes or VFDs and the Return/Exhaust Fan Capacity Control Flag is set to “Tracking”, the controller uses VaneTrol fan tracking logic to control the return fan capacity. With the VaneTrol logic method, the return fan capacity (indicated by the RF/EF Fan Cap= parameter) varies with or “tracks” the discharge fan capacity (indicated by the Disch Fan Cap= parameter) as the discharge fan is controlled to maintain the duct static pressure or position set point. The result is that proper building pressure is maintained regardless of the building cooling or heating load.

Note: The Second Pressure Sensor Present Flag must be set to either “None” or “Duct” to use the fan track-ing control method.

VaneTrol logic uses two sets of four tracking parameters to control the return fan capacity. One set is used when an external exhaust fan is on (indicated when binary input MCB-BI13 is on), and the other set is used when the external exhaust fan is off or not present (indicated when binary input MCB-BI13 is off). Refer to Figure 19.To take advantage of the external exhaust fan compensation feature, the exhaust fan status must be provided to the controller through a field supplied contact closure wired to binary input MCB-BI13. For detailed information regarding this input, refer to “External Exhaust Fan Status” in the



Menu Name Item Name

Timer Settings Post Heat= 0 min Post Heat Timer



Menu Name Item Name


Sensor Present Flag

RF/EFCtrl= Tracking Return/Exhaust Fan Capacity Control Flag

Fan Tracking

DF Max w/oExh= 100% Maximum Discharge Without Exhaust

RF@DFMax w/oEx= 95% Maximum Return Without Exhaust

DF Min w/oExh= 20% Minimum Discharge Without Exhaust

RF@DFMin w/oEx= 15% Minimum Return Without Exhaust

DF Max w/Exh= 100% Maximum Discharge With Exhaust

RF@DFMax w/Ex= 60% Maximum Return With Exhaust

DF Min w/Exh= 20% Minimum Discharge With Exhaust

RF@DFMin w/Ex= 10% Minimum Return With Exhaust

OM-137-2 109

“Field Wiring” section of IM696, MicroTech II Applied Rooftop Unit Controller.

Figure 19: VaneTrol Fan Tracking Logic

The default fan tracking parameters typically require field adjustment for proper control. During unit startup, an experienced air balance technician should enter the appropriate fan tracking parameters by using the procedure describe in “Automatic Discharge/Return Fan Balancing Procedure” on page 110. This automatic balance procedure sets the eight fan tracking parameters listed in Table 63 on page 109. These then can then be manually adjusted to fine-tune the building static pressure control if necessary. These fan tracking parameters are described in the following section.When the external exhaust fan is off (binary input MCB-BI13 off) and the Disch Fan Cap= parameter value is at the Maximum Discharge Without Exhaust value, the RF/EF Fan Cap= parameter value is controlled to the Maximum Return Without Exhaust value. When the external exhaust fan is off (binary input MCB-BI13 off) and the Disch Fan Cap= parameter value is at the Minimum Discharge Without Exhaust value, the RF/EF Fan Cap= parameter value is controlled to the Minimum Return Without Exhaust value.When the external exhaust fan is on (binary input MCB-BI13 on) and the Disch Fan Cap= parameter value is at the Maximum Discharge With Exhaust value, the RF/EF Fan Cap= parameter value is controlled to the Maximum Return With Exhaust value. When the external exhaust fan is on (binary input MCB-BI13 on) and the Disch Fan Cap= parameter value is at the Minimum Discharge With Exhaust value, the RF/EF Fan Cap= parameter value is controlled to the Minimum Return With Exhaust value.Return fan tracking control is overridden under two conditions. 1. The first condition is when the return inlet vanes modu-

lates down to 17% or the VFD speed is reduced to 25%.

The controller does not allow the capacity to modulate below these fixed values.

2. The second condition is when the outdoor air dampers are completely closed. In this case the return fan capac-ity tracks the discharge fan capacity one-to-one.

Automatic Discharge/Return Fan Balancing Procedure

Determining the correct VaneTrol fan tracking parameters can be accomplished using the following balance feature procedures. Different procedures are given for applications with and without an external exhaust fan that operates intermittently while the unit is running.

Note: The discharge/return fan balancing procedure must be performed as part of the system air balancing during unit startup, and unit startup must be per-formed in accordance with the “Check, Test, and Start Procedures” section in the installation manual supplied with the unit (refer to Table 1 on page 4).

(DFMax w/oExh= 100%,RF@DFMax w/oEx= 95%)

(DFMax w/Exh= 100%,RF@DFMax w/Ex= 50%)

(DFMin w/oExh= 20%,RF@DFMin w/Ex= 60%

DFMin wEhx= 20%,RF@DFMin w/Ex= 10%

MinimumAirflow

MaximumAirflow

Exhaust Fan On

Exhaust Fan Off

Supply Airflow %

Re

turn

Air

flo

w%



Menu Name Item Name

Fan Balance

Fan Balance= Off Balance Mode Flag

Set Max w/o Exh= No Set Maximum/EF Off Flag

Set Min w/o Exh= No Set Minimum/EF Off Flag

Set Max w/ Exh= No Set Maximum/EF On Flag

Set Min w/ Exh= No Set Minimum/EF On Flag

Rem RF/EF Cap= 25% Remote Return/Exhaust Fan Capacity Set Point

110 OM-137-2

Note: If the Calibrate Mode= parameter in the Unit Con-figuration menu is set to “Yes” while the Balance Mode Flag is set to “On”, the Balance Mode Flag reverts to “Off.”

Note: The Balance Mode Flag cannot be set to “On” when the unit operating state is less than Fan Only (i.e. Off, Startup or Recirc).

Systems without an Intermittent External Exhaust Fan1. With the unit fans running, the Balance Mode Flag is set

to “On”. The controller enters the Balance operating state. Heating and cooling operation are disabled during the Balance operating state.

2. The VAV box system is manually set up for the maxi-mum airflow. Since normal duct static pressure control is maintained during the Balance operating state, the discharge fan should modulate toward full capacity.

3. When the discharge fan stabilizes maintaining the duct static pressure set point, the return fan capacity is manu-ally adjusted using the Remote Return/Exhaust Fan Capacity Set Point until the desired building static pres-sure is obtained.

4. When the system has stabilized and the desired building static pressure is achieved, the Set Maximum/EF Off Flag is set to “Yes.” This causes the controller to read and store the current discharge and return fan capacity values (as indicated by the Disch Fan Cap= and RF/EF Fan Cap= parameters) as the Maximum Discharge Without Exhaust and Maximum Return Without Exhaust fan tracking parameters (refer to “VaneTrol Fan Tracking Control” on page 109). The Set Maximum/EF Off Flag “Yes” entry automatically reverts to “No” after the values are recorded.

5. The VAV box system is then manually set up for mini-mum airflow. Since normal duct static pressure control is maintained during the Balance operating state, the discharge fan should modulate toward minimum capac-ity.

6. Step 3 is then repeated.7. When the system has stabilized and the desired building

static pressure is achieved, the Set Minimum/EF Off Flag is set to “Yes.” This causes the controller to read and store the current discharge and return fan values (as indicated by the Disch Fan Cap= and RF/EF Fan Cap= parameters) as the Minimum Discharge Without Exhaust and Minimum Return Without Exhaust fan tracking parameters (refer to “VaneTrol Fan Tracking Control” on page 109). The Set Minimum/EF Off Flag “Yes” entry automatically reverts to “No” after the val-ues are recorded.

8. The Balance Mode Flag is set back to “Off” and normal operation resumes.

Systems with an Intermittent External Exhaust Fan1. With the unit fans and the intermittent exhaust fan run-

ning (binary input MCB-BI13 on), the Balance Mode

Flag is set to “On”. The controller enters the Balance operating state. Heating and cooling operation are dis-abled during the Balance operating state.

2. The VAV box system is manually set up for maximum airflow. Since normal duct static pressure control is maintained during the Balance operating state, the dis-charge fan should modulate toward full capacity.

3. When the discharge fan stabilizes maintaining the duct static pressure set point, the return fan capacity is manu-ally adjusted using the Remote Return/Exhaust Fan Capacity Set Point until the desired building static pres-sure is obtained.

4. When the system has stabilized and the desired building static pressure is achieved, the Set Maximum/EF On Flag is set to “Yes.” This causes the controller to read and store the current discharge and return fan capacity values (as indicated by the Disch Fan Cap= and RF/EF Fan Cap= parameters) as the Maximum Discharge With Exhaust and Maximum Return With Exhaust fan track-ing parameters (refer to “VaneTrol Fan Tracking Con-trol” on page 109). The Set Maximum/EF On Flag “Yes” entry automatically reverts to “No” after the val-ues are recorded.

5. Next the external exhaust fan is shut off (binary input MCB-BI13 off) and step 3 is repeated.

6. When the system has stabilized and the desired building static pressure is achieved, the Set Maximum/EF Off Flag is set to “Yes.” This causes the controller to read and store the current discharge and return fan capacity values (as indicated by the Disch Fan Cap= and RF/EF Fan Cap= parameters) as the Maximum Discharge Without Exhaust and Maximum Return Without Exhaust fan tracking parameters (refer to“VaneTrol Fan Tracking Control” on page 109). The Set Maximum/EF Off Flag “Yes” entry automatically reverts to “No” after the values are recorded.

7. The VAV box system is then manually set up for mini-mum airflow. Since normal duct static pressure control is maintained during the Balance operating state, the discharge fan should modulate toward minimum capac-ity.

8. Step 3 is then repeated.9. When the system has stabilized and the desired building

static pressure is achieved, the Set Minimum/EF Off Flag is set to “Yes.” This causes the controller to read and store the current discharge and return fan capacity values (as indicated by the Disch Fan Cap= and RF/EF Fan Cap= parameters) as the Minimum Discharge Without Exhaust and Minimum Return Without Exhaust fan tracking parameters (refer to “VaneTrol Fan Track-ing Control” on page 109). The Set Minimum/EF Off Flag “Yes” entry automatically reverts to “No” after the values are recorded.

10. Next the external exhaust fan is turned on (binary input MCB-BI13 on) and Step 3 is repeated.

11. When the system has stabilized and the desired building static pressure is achieved, the Set Minimum/EF On

OM-137-2 111

Flag is set to “Yes.” This causes the controller to read and store the current discharge and return fan capacity values (as indicated by the Disch Fan Cap= and RF/EF Fan Cap= parameters) as the Minimum Discharge With Exhaust and Minimum Return With Exhaust fan track-ing parameters (refer to “VaneTrol Fan Tracking Con-trol” on page 109). The Set Minimum/EF On Flag “Yes” entry automatically reverts to “No” after the values are recorded.

12. The Balance Mode Flag is set back to “Off” and normal operation resumes.

Direct Building Static Pressure Control

When a unit is equipped with return or exhaust fan inlet guide vanes or VFDs they can be controlled based on building static pressure. Note that this feature requires an optional building static pressure sensor. When the Return/Exhaust Fan Capacity Control Flag is set to “BldgPres” and the Second Pressure Sensor Present Flag is set to “Bldg”, the controller modulates the return fan capacity to maintain the Building Static Pressure Set Point. To do this it uses three PID control loop parameters to modulate the return capacity as the building static pressure changes. Theses are Building Static Pressure Proportional Band, Building Static Pressure Integral Time and Building Static Pressure Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters; refer to “MicroTech II DDC Features” on page 126.Building static pressure control of the return air fan airflow is overridden under two conditions. 1. The first condition is when the return fan capacity mod-

ulate down to 17% or the VFD speed is reduced to 25%. The controller does not allow the return fan capacity to modulate below these fixed values.

2. The second condition is when the outdoor air dampers are completely closed. In this case the return fan capac-ity tracks the discharge fan capacity one-to-one. In the case of a constant volume discharge fan the return fan airflow is driven to 100%.

Return Fan Direct Position Control

When a unit is equipped with return or exhaust fan inlet guide vanes or VFDs, the inlet guide vane position or VFD speed can be controlled to a specific position set point based on a network signal. When the Return/Exhaust Fan Capacity Control Flag is set to “Position”, the controller positions the return or exhaust fan inlet vanes or VFD speed to the Remote Return/Exhaust Fan Capacity Set Point. Normal building static pressure control is overridden in this case. If network communications is interrupted or is not present, the Remote Return/Exhaust Fan Capacity Set Point remains at the last commanded setting and then can be adjusted via the unit keypad/display. The Remote Return/Exhaust Fan Capacity Set Point can be adjusted from the fixed minimum (17% for vanes or 25% for VFD applications) to 100%. When the Return/Exhaust Fan Capacity Control Flag is set to “BldgPres” or “Tracking”, the Remote Return/Exhaust Fan Capacity Set Point has no effect on the unit operation.

Note: The Return Fan Direct Position Control Function is used during the Automatic Discharge/Return Fan Balancing Procedure. Refer to “Automatic Dis-charge/Return Fan Balancing Procedure” on page 110.

SAF/RAF Differential OA ResetWhen a unit is equipped with return air fan inlets vanes or VFD it may be necessary to increase the amount of outdoor air if the difference between the discharge and return fan capacity gets to large. If this is not done the discharge air fan can potentially become “starved” for air. A discharge fan operating in a “starved” condition not only has difficulty meeting the system airflow requirements but may cause excessive vibration and/or damage to damper sets and/or return fan motors or VFD. To overcome this type of problem, the MicroTech II unit controller provides a discharge/return fan differential OA reset strategy, which automatically resets outdoor air dampers as the difference between the discharge and return air fan capacity varies. Refer to “Discharge/Return Fan Differential OA Reset” on page 81.



Menu Name Item Name

Bldg PressureBldgSP Spt= 0.050 “WC Building Static

Pressure Set Point



BSP Propbd= 1.0 “WCBuilding Static

Pressure Proportional Band

BSP IntTime= 10 secBuilding Static

Pressure Integral Time

BSP Period= 5 sec Building Static Pressure Period


Sensor Present Flag

RF/EFCtrl= Tracking Return/Exhaust Fan Capacity Control Flag



Menu Name Item Name

Unit Configuration

RF/EF Ctrl= TrackingReturn/Exhaust Fan


Rem RF/EF Cap= 25%

Remote Return/Exhaust Fan Capacity Set Point

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Propeller Exhaust Fan ControlWhen a unit is equipped with the propeller exhaust fan option, it is equipped with a VFD to control the speed of the propeller fan(s). There are two different methods for controlling the exhaust fan capacity. These are “direct building static pressure” control and “position” control. The following sections describe the two methods.

Direct Building Static Pressure Control

When a unit is equipped with the propeller exhaust fan option and, therefore, is equipped with a VFD for controlling the speed of the propeller fan(s), the VFD can be controlled based on building static pressure.

Note: This control option requires an optional building static pressure sensor, the Return/Exhaust Fan Capacity Control Flag is set to “BldgPres” and the Second Pressure Sensor Present Flag is set to “Bldg”.

Exhaust Fan Start/Stop Control The exhaust fans are started when all of the following conditions are met for longer than the Minimum Start Time setting:1. The current OA Damper= value is above the Minimum

Outdoor Air Damper Position setting.

2. The current Disch Fan Cap= value is above the Mini-mum Discharge Fan Capacity setting (or the unit has a constant volume discharge fan).

3. The current Bldg Press= value is above the Building Static Pressure Set Point by more than half the Building Static Pressure Dead Band.

The exhaust fans are stopped when the current Bldg Press= value is below the Building Static Pressure Set Point by more than half the Building Static Pressure Dead Band and the current RF/EF Fan Cap= value has been at or below the Minimum Exhaust Fan Capacity for longer than the Minimum Stop Time.Exhaust Fan VFD Speed ControlWhen the exhaust fans are on, the speed of the exhaust fan VFD is controlled to maintain the current Bldg Pres= value at the Building Static Pressure Set Point. To do this the controller uses three PID control loop parameters to modulate the exhaust fan capacity as the building pressure changes. These are the Building Static Pressure Proportional Band, Building Static Pressure Integral Time and Building Static Pressure Period. Although these parameters can be adjusted, for most applications, the factory default values for these parameters provide the best control. For detailed information regarding tuning PID control loop parameters, refer to “MicroTech II DDC Features” on page 126.

Exhaust Fan Direct Position Control

When a unit is equipped with the propeller exhaust fan option and, therefore, is equipped with a VFD for controlling the speed of the propeller fan(s), the VFD can be controlled to a specific position set point based on a network signal.

Note: This control option requires that the Return/Exhaust Fan Capacity Control Flag is set to “Position”.



Menu Name Menu Item

Bldg Pressure

BldgSP Spt= 0.050 “WC

Building Static Pressure Set Point



BSP Propbd= 1.0 “WC Building Static Pressure Proportional Band

BSP IntTime= 10 Sec Building Static Pressure Integral Time

BSP Period= 5 Sec Building Static Pressure Period

Exhaust Fan Setup

Min Exh Fan Cap= 25%

Minimum Exhaust Fan Capacity

Min OA Dmpr Pos= 5%

Minimum Outdoor Air Damper Position

Min DF Cap= 10% Minimum Discharge Fan Capacity

Min Strt Time= 120 Sec Minimum Start Time

Min Stop Time= 120 Sec Minimum Stop Time

Unit Configuration





Menu Name Menu Item

Exhaust Fan Setup

Min Exh Fan Cap= 25% Minimum Exhaust Fan Capacity

Min OA Dmpr Pos= 5%Minimum Outdoor Air

Damper Position

Min DF Cap= 10% Minimum Discharge Fan Capacity

Min Strt Time= 120 Sec Minimum Start Time

Min Stop Time= 120 Sec Minimum Stop Time

Unit Configuration


Rem RF/EF Cap= 25%Remote

Return/Exhaust Fan Capacity Set Point

OM-137-2 113

Exhaust Fan Start/Stop Control The exhaust fans are started when all of the following conditions are met for longer than the Minimum Start Time setting:1. The current OA Damper= value is above the Minimum

Outdoor Air Damper Position setting.2. The current Disch Fan Cap= value is above the Mini-

mum Discharge Fan Capacity setting (or the unit has a constant volume discharge fan).

3. The Remote Return/Exhaust Fan Capacity Set Point is set to a value above the Minimum Exhaust Fan Capacity setting.

The exhaust fans are stopped when the Remote Return/Exhaust Fan Capacity Set Point is set equal to the Minimum Exhaust Fan Capacity setting for longer than the Minimum Stop Time.Exhaust Fan VFD Speed ControlWhen the exhaust fans are on and the Return/Exhaust Fan Capacity Control Flag is set to “Position”, the speed of the exhaust fan VFD is controlled to the Remote Return/Exhaust Fan Capacity Set Point. Normal building static pressure control is overridden in this case. If network communications is interrupted or is not present, the Remote Return/Exhaust Fan Capacity Set Point remains at the last commanded setting and then can be adjusted via the unit keypad/display. The Remote Return/Exhaust Fan Capacity Set Point can be adjusted from 0% to 100%.

Unoccupied ControlUnoccupied Heating (Night Setback)

If an optional space (or zone) temperature sensor (ZNT1) is connected to the controller, the Space Sensor Present Flag is set to “Yes” and the Unoccupied Heating Set Point is set higher than 0°F, unoccupied heating (night setback) operation is available. Unoccupied heating operation is disabled if either the Space Sensor Present Flag is set to “No” or the Unoccupied Heating Set Point is set to 0°F. The following is a description of unoccupied heating operation:If the space temperature falls to the Unoccupied Heating Set Point while the unit is in the Off Unoc operating state, the unit starts and runs.1 The controller enters the UnocHtg operating state after the normal startup sequence. Refer to “Startup Control” on page 74. The UnocHtg operating state

is similar to the Heating operating state except that the outdoor air dampers remain closed in the UnocHtg operating state. When the space temperature rises above the Unoccupied Heating Set Point by more than the Unoccupied Heating Differential, heating operation ends and the controller shuts down the fans and returns to the Off Unoc state.

Note: The Unoccupied Heating Set Point cannot be set higher than the Occ Htg Spt= parameter.

Emergency Space Sensor Failure OperationThe unit starts and runs in an emergency mode of operation if all of the following are true:1. The Space Sensor Present Flag is set to “Yes”2. The Unoccupied Heating Set Point is set higher than 0°F3. The current value of the OA Temp= parameter is below

40°F.4. The Space Temp problem alarm occurs.5. Unit is equipped with a functioning return temperature

sensor.In this mode of operation the unit starts and runs continuously using the return air temperature sensor as the “Control Temperature.” Refer to “Control Temperature” on page 75.

Unoccupied Cooling (Night Setup)

If an optional space (or zone) temperature sensor (ZNT1) is connected to the controller, the Space Sensor Present Flag is set to “Yes” and the Unoccupied Cooling Set Point is set lower than 99°F, unoccupied cooling (night setup) operation is available. Unoccupied cooling operation is disabled if either the Space Sensor Present Flag is set to “No” or the Unoccupied Cooling Set Point is set to 99°F. The following is a description of unoccupied cooling operation:If the space temperature rises to the Unoccupied Cooling Set Point while the unit is in the Off Unoc state, the unit starts and runs.1 If the unit has an economizer and the OA Ambient= parameter indicates “Low”, the controller enters the UnocEcon operating state after the normal startup sequence. If OA Ambient= parameter indicates “High” or the outdoor air is not cool enough to maintain the Eff Clg Spt=



Menu Name Item Name

Zone HeatingUnoccHtg Spt= 55.0 ºF Unoccupied Heating

Set Point

UnoccHtgDiff= 3°F Unoccupied Heating Differential


1. The unit does not activate unoccupied heating or cooling operation if the UnitStatus= parameter in the System menu indicates “Off Man”, “Off Sw”, “Off Net” or “Off Alm.”



Menu Name Item Name

Zone CoolingUnoccClg Spt= 85.0 ºF Unoccupied Cooling

Set Point

UnoccClgDiff= 3°F Unoccupied Cooling Differential


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setting in the Discharge Cooling menu (or the unit has no economizer), the controller enters the UnocClg operating state and activates mechanical cooling after the normal startup sequence. The UnocEcon and UnocClg operating states are similar to the Econo and Cooling operating states except that the Eff MinOA Pos= parameter is set to 0%. If the OA Ambient= parameter indicates “Low”, the outdoor air dampers are wide open during UnocClg. If the OA Ambient= parameter indicates “High” (or there is no economizer), the outdoor air dampers are fully closed during UnocClg.When the space temperature drops below the Unoccupied Cooling Set Point by more than the Unoccupied Cooling Differential, cooling operation ends and the controller shuts down the fans and returns to the Off Unoc state.

Note: The Unoccupied Cooling Set Point cannot be set lower than the Occ Clg Spt= parameter.

Purge

If a unit is equipped with an economizer and an optional space (or zone) temperature sensor (ZNT1) is connected to the controller, pre-occupancy purge control is available. Designed to take advantage of cool pre-dawn outdoor air, purge control starts the fans and modulates the economizer dampers to maintain occupied cooling requirements during unoccupied periods. The purge function can only be used in conjunction with the unit internal time schedule.Purge operation is possible only during a time window prior to occupancy that is defined by the Maximum Purge Time parameter (0 to 240 minutes). For example, if the unit is scheduled to start at 6:30 a.m., a Maximum Purge Time of 60 minutes (default) allows purge operation to occur between 5:30 a.m. and 6:30 a.m.During the purge time window, the unit starts and runs when the following three requirements are all met:

• The Space Temp= value is greater than the Effective Cooling Enable Set Point by more than half the Cooling Enable Deadband.

• The OA Ambient= value in the OA Damper menu indi-cates “Low.”

• The OA Temp= value is below the Space Temp= value by more than 4°F.

During purge operation, the controller enters and remains in the UnocEcon operating state after the normal startup

sequence. Mechanical cooling is disabled. Economizer control during purge operation is similar to that during occupied operation.The unit returns to the Off Unoc state when any of the following three conditions occur:

• The Space Temp= value is less than the Effective Cool-ing Enable Set Point by more than half the Cooling Enable Deadband.

• The OA Ambient= value in the OA Damper menu indi-cates “High.”

• The OA Temp= value rises above the Space Temp= value by more than 2°F.

As conditions allow, purge control cycles the unit in this manner until normal occupied operation begins. If the scheduled occupied startup time occurs during purge operation, the unit continues running without interruption.

Special Space Sensor Failure Operation


When a unit is equipped with an optional space (or zone) temperature sensor (ZNT1) a special “space sensor failure” mode of operation is available if the unit is also equipped with a functioning return air temperature sensor. This special mode of operation is activated when all of the following conditions are met:1. The Space Sensor Present Flag is set to “Yes”.2. The Unoccupied Heating Set Point is set higher

than 0°F.3. The current OA Temp= value is below 40°F.4. The space temperature sensor fails while the unit is in

the Off Unoc operation state.In this mode, the unit starts up and runs as it normally would during an occupied period, controlling temperature using the return air sensor as the Control Temperature Source.

Alarm ControlThe following are descriptions of the various alarms that can occur in discharge air control (DAC) rooftop units.

Note: The cause of a manual reset alarm should be inves-tigated and eliminated before the unit or any dis-abled equipment in it is placed back into service.



Menu Name Item Name

Zone CoolingEff Clg Spt= 75.0 ºF Effective Cooling

Enable Set Point

Clg Deadband= 1.0 ºF Cooling Enable Deadband

OA Damper Max Purge= 60 min Maximum Purge Time


Menu Name Menu Item

Zone HeatingCntlTempSrc= Return Control Temperature

Source

UnoccHtg Spt= 55°F Unoccupied Heating Set Point

Unit Configuration Space Sensor= Yes Space Sensor Present

Flag

OM-137-2 115

FaultsFreezeWhen a unit is equipped with a chilled water, hot water, or steam coil, the Freeze fault occurs when the optional freezestat (FS1) contacts open (binary input MCB-BI7 off) as a result of detecting an abnormally low water or steam coil temperature while the fans are running.When the Freeze fault occurs, the controller shuts down the fans, closes the outdoor air dampers, opens the chilled water and heating valves and sets a 10-minute timer.When the 10-minute timer expires, the controller checks the freezestat input again. If the freezestat contacts are closed (binary input MCB-BI7 on), the valves close. If the freezestat contacts are still open (binary input MCB-BI7 off), the valves remain open, and the 10-minute timer resets. This continues until the fault is manually cleared through the unit keypad or via a network signal.SmokeThe Smoke fault occurs when the contacts of either optional discharge or return air smoke detector (SD1 or SD2) open (binary input MCB-BI8 off).When the Smoke fault occurs, the unit is immediately shut down. The unit remains shut down until the smoke detector is manually reset and the Smoke fault is manually cleared through the unit keypad or via a network signal.

Note: The smoke detector can be reset by pressing the reset button on or momentarily removing power from the device. This can be accomplishes by cycling control power (S1 switch).

OAT SensorIf the outdoor air temperature sensor (OAT) fails (analog input MCB-AI5 open or short-circuited) while it is acting as the “Control Temperature” (CtrlTemp Src= parameter is set to “OAT”), the OAT Sensor fault occurs.When the OAT Sensor fault occurs, the unit is shut down. It remains shut down until the OAT Sensor fault is manually cleared through the unit keypad or via a network signal.Space SensorIf the optional space temperature sensor (ZNT1) fails (analog input MCB-AI1 open or short-circuited) while it is acting as the “Control Temperature” (CtrlTemp Src= parameter is set to “Space”) and the unit has no return air sensor, the Space Sensor fault occurs.When the Space Sensor fault occurs, the unit is shut down. It remains shut down until the Space Sensor fault is manually cleared through the unit keypad or via a network signal.Return SensorIf the unit is equipped with a return air temperature sensor (RAT) and it fails (analog input MCB-AI4 open or short-circuited) while it is acting as the “Control Temperature” (CtrlTemp Src= parameter is set to “Return”), the Return Sensor fault occurs.

When the Return Sensor fault occurs, the unit is shut down. It remains shut down until the Return Sensor fault is manually cleared through the unit keypad or via a network signal.Disch SensorIf the discharge air temperature sensor (DAT) fails (analog input MCB-AI3 open or short-circuited), the Disch Sensor fault occurs.When the Disch Sensor fault occurs, the unit is shut down. It remains shut down until the Disch Sensor fault is manually cleared through the unit keypad or via a network signal.Duct Hi LimitIf the unit is equipped with discharge fan inlet vanes or a VFD and the contacts of the duct high pressure limit control (DHL) open (binary input MCB-BI14 off), the Duct Hi Limit fault occurs.When the Duct Hi Limit fault occurs, the unit is shut down. The unit remains shut down until the Duct Hi Limit fault is manually cleared through the unit keypad or via a network signal.Hi Return TmpIf the unit is equipped with a return air temperature sensor and the Return Air= parameter value exceeds the Hi Return Alm= value in the Alarm Limits menu, while the unit is operational, the Hi Return Tmp fault occurs.When the Hi Return Tmp fault occurs, the unit is shut down. It remains shut down until the Hi Return Tmp fault is manually cleared through the unit keypad or via a network signal.Hi Disch TmpIf the Disch Air= parameter value exceeds the Hi Disch Alm= setting in the Alarm Limits menu, while the unit is operational, the Hi Disch Tmp fault occurs.When the Hi Disch Tmp fault occurs, the unit is shut down. It remains shut down until the Hi Disch Tmp fault is manually cleared through the unit keypad or via a network signal.Lo Disch TmpIf the Disch Air= parameter value drops below the Lo Disch Alm= setting in the Alarm Limits menu for longer than 3 minutes while the unit is operational, the Lo Disch Tmp fault occurs.When the Lo Disch Tmp fault occurs, the unit is shut down. It remains shut down until the Lo Disch Tmp fault is manually cleared through the unit keypad or via a network signal.

Note: The Lo Disch Tmp fault is ignored when the unit leaves the Startup operating state for a time period defined by the Low DAT= parameter in the Timer Settings menu and when the unit is in the Cooling operating state.

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Fan FailIf differential pressure switch PC7 fails to detect airflow (binary input MCB-BI6 off) within two minutes after the unit leaves the Startup operating state or any time afterward, while the unit is running, the Fan Fail fault occurs.When the Fan Fail fault occurs, the unit is shut down. It remains shut down until the Fan Fail fault is manually cleared through the unit keypad or via a network signal.Exceptions:1. If the unit is equipped with discharge fan inlet vanes or a

discharge fan VFD and “post heat” operation is active, the Fan Fail fault is ignored during “post heat” and for two minutes following “post heat” operation. While the Fan Fail fault is being ignored, the unit does not leave the Fan Only or Min DAT operating state. For detailed information regarding “post heat” operation, refer to “Post Heat Operation” on page 109.

2. On units equipped with a discharge fan VFD, the Fan Fail fault only occurs if the Fan Retry problem described below has first occurred twice within the pre-vious twenty-four hour period. The conditions that cause the Fan Retry problem and the action taken are the same as for the Fan Fail fault. The difference being that the Fan Retry alarm is an automatically clearing alarm once the unit is shut off. This allows the unit to attempt to restart up to three times within a twenty-four hour period.

Note: The three retry counter is reset anytime the unit is disabled by any of the following reasons:

1. Fault alarm2. External enable/disable switch input3. Ctrl Mode= parameter in the System menu set to “Off”4. Emerg Override= parameter in the Occupancy menu set

to “Off”.5. Appl Mode= parameter in the System menu set to “Off”

via a network signal.OA Dmpr StuckOn units equipped with a 100% outdoor air hood, the outdoor air dampers are driven fully open during the Startup operating state before the discharge fan is started. If the OA Damper Pos= parameter in the OA Damper menu does not indicate 50% or greater when the unit leaves the Startup operating state, the OA Dmpr Stuck fault occurs.When the OA Dmpr Stuck fault occurs, the unit is shut down. The unit remains shut down until the OA Dmpr Stuck fault is manually cleared through the unit keypad or via a network signal.

ProblemsFreezeWhen a unit is equipped with a chilled water, hot water, or steam coil, the Freeze problem occurs when the optional freezestat (FSl) contacts open (binary input MCB-BI7 off) as

a result of detecting an abnormally low water or steam coil temperature while the fans are off.When the Freeze problem occurs, the controller opens the chilled water and heating valves and set a 10-minute timer.When the 10-minute timer expires, the controller checks the freezestat input again. If the freezestat contacts are closed (binary input MCB-BI7 on), the valves close. If the freezestat contacts are still open (binary input MCB-BI7 off), the valves remain open, and the 10-minute timer resets. This continues while the unit remains off.Whenever the freezestat closes (binary input MCB-BI7 on), the Freeze problem automatically clears. This feature protects the coil(s) and allows the system to start normally when an occupied command is received.OAT SensorIf the outdoor air temperature sensor (OAT) fails (analog input MCB-AI5 open or short-circuited) and it is not acting as the “Control Temperature” (CtrlTemp Src= parameter is not set to “OAT”), the OAT Sensor problem occurs.When the OAT Sensor problem occurs, the unit continues to operate with the following modifications:1. Discharge temperature set point reset based on outdoor

air is unavailable.2. Compressor low ambient lockout is disabled.3. High ambient heating lockout is disabled.4. Purge operation is disabled.

When the alarm condition is no longer present, the OAT Sensor problem automatically clears.Space SensorIf the optional space temperature sensor ZNT1 fails (analog input MCB-AI1 open or short-circuited) on a unit equipped with a return air temperature sensor, the Space Sensor problem occurs as long as the Space Sensor= parameter in the Unit Configuration menu is set to “Yes.” If this parameter is set to “No” the Space Sensor problem indication is disabled.When the Space Sensor problem occurs, the unit continues to operate with the following modifications:1. Discharge temperature set point reset based on space

temperature is unavailable.2. Purge operation is disabled. 3. If the space temperature input is acting as the “Control

Temperature” (CtrlTemp Src= parameter is set to “Space”), the controller automatically changes the Ctr-lTemp Src= parameter to “Return” if the unit is equipped with a functioning return air temperature sensor.

When the Space Sensor problem occurs during an unoccupied time period, the unit starts and runs continuously in the UnocHtg operating state, using the return air temperature sensor as the “Control Temperature” if all of the following conditions are true:1. The unit is equipped with a functioning return air tem-

perature sensor.

OM-137-2 117

2. The OA Temp= parameter value is below 40 °F. 3. The UnoccHtg Spt= parameter in the Zone Heating

menu is set higher than 0°F. When the alarm condition is no longer present, the Space Sensor problem automatically clears and normal unit operation resumes.Return SensorIf the return air temperature sensor (RAT) fails (analog input MCB-AI4 open or short-circuited) while it is not acting as the “Control Temperature” (CtrlTemp Src= parameter is not set to “Return”), the Return Sensor problem occurs.When the Return Sensor problem occurs, the unit continues to operate with the following modifications:1. Discharge temperature set point reset based on return

temperature is unavailable.2. The Hi Return Tmp fault is disabled.

When the alarm condition is no longer present, the Return Sensor problem automatically clears.Ent Fan SensorIf the unit is equipped with an entering fan air temperature sensor (EFT) and it fails (analog input MCB-AI6 open or short-circuited), the Ent Fan Sensor problem occurs as long as the EFT Sensor= parameter in the Unit Configuration menu is set to “Yes.” If this parameter is set to “No” the Ent Fan Sensor problem indication is disabled.When the Ent Fan Sensor problem occurs, the unit continues to operate with the following modifications.1. The Low Airflow problem alarm is disabled.2. The function on gas or electric heat units that limits the

Eff Htg Spt= parameter in the Discharge Heating menu based the maximum heat rise for the heat exchanger on units equipped with gas or electric heat is disabled. Refer to “Heating: Multistage” on page 94 (electric heat units) or “Gas Heat” on page 97 (gas heat units).

When the alarm condition is no longer present, the Ent Fan Sensor problem automatically clears.

Note: Note that the EFT sensor is only provided with units that have gas or electric heat.

Low AirflowThe Low Airflow problem is a safety designed to protect the heat exchanger on units equipped with one-stage of gas or one-stage or multistage electric heat. If the temperature rise across the gas furnace heat exchanger or electric heater on a single stage heater exceeds a factory set limit or if the discharge air temperature exceeds 145°F, the Low Airflow problem occurs. Refer to“Heating: One Stage” on page 93.The Low Airflow problem also can occur if the unit is equipped with multistage electric heat. If communications is lost between the Main Control Board (MCB) and the Electric Heat Control Board (EHB1) and the temperature rise across the electric heater on exceeds a factory set limit or if the

discharge air temperature exceeds 145°F, the alarm will occur. Refer to “Heating: Multistage” on page 94.When the Low Airflow problem occurs, the unit continues to operate, but the heating system is disabled. It remains disabled until the Low Airflow problem is manually cleared through the unit keypad or via a network signal.The controller determines the temperature rise across the heating section by subtracting the Ent Fan= value from the Disch Air= value. The factory set temperature rise limit varies and depends on the unit heating system configuration. This maximum heat rise value can be found on the gas or electric heat data plate attached to the unit.

Note: Units with one-stage of heat are intended to be operated at full airflow when the heating equipment is active. The VAV Box Output (MCB-BO12) can be used to force the VAV boxes open when the unit is supplying heat. For detailed information regard-ing the VAV Box Output, refer to the “Field Wir-ing” section of IM696, MicroTech II Applied Rooftop Unit Controller.

Heat FailIf a unit is equipped with a gas furnace (one-stage or modulating) and the burner flame safeguard (FSG) control enters the “safety lockout” state after a call for heat, relay R24 energizes and closes a set of contacts and delivers a binary input (binary input MCB-BI5 on) to the controller. When this binary input is present the Heat Fail problem occurs.When the Heat Fail problem occurs, the unit continues to operate with the heating system disabled by the FSG. Heating remains disabled until the flame safeguard control is manually reset. When the FSG is reset, relay R24 de-energizes, removing the binary input (binary input MCB-BI5 off) from the controller, causing the Heat Fail problem to automatically clear.For detailed information regarding the FSG control, refer to the separate installation manual supplied with the gas furnace and the “Sequences of Operation” section of the model-specific installation manual (refer to Table 1 on page 4).Fan RetryWhen a unit is equipped with a discharge fan VFD and if the differential pressure switch PC7 fails to detect airflow (binary input MCB-BI6 off) within two minutes after leaving the Startup operating state or any time afterward while the unit is running, the Fan Retry problem occurs.When the Fan Retry problem occurs, the unit is shut down. Once the unit is shut down the Fan Retry problem is automatically cleared and the unit is free to restart.Exceptions:1. If “post heat” operation is active, the Fan Retry problem

is ignored during “post heat” and for two minutes fol-lowing “post heat” operation. While the Fan Retry prob-

118 OM-137-2

lem is being ignored, the unit does not leave the Fan Only or Min DAT operating state. For detailed informa-tion regarding “post heat” operation, refer to “Post Heat Operation” on page 109.

2. The Fan Retry problem only will occur twice within a twenty-four hour period. If the conditions that cause the Fan Retry problem occur a third time within this period, the Fan Fail fault described above occurs instead. The action taken as a result of the Fan Fail fault is the same as that for the Fan Retry alarm, the difference being that the Fan Retry alarm is an automatically clearing alarm once the unit is shut off while the Fan Fail fault requires a manual clearing. This allows a unit equipped with a discharge fan VFD to attempt to restart up to three times within a twenty-four hour period.

Note: The three retry counter is reset anytime the unit is disabled by any of the following methods:

1. Fault alarm2. External enable/disable switch input3. Ctrl Mode= parameter in the System menu set to “Off”4. Emerg Override= parameter in the Occupancy menu set

to “Off”.5. Appl Mode= parameter in the System menu set to “Off”

via a network signal.Hi Pres-Ckt1This alarm occurs on units equipped with compressorized cooling only. If either of the cooling circuit #1 high pressure switches (HP1 or HP3) opens (binary input CCB1-BI7 off), indicating a high refrigerant pressure situation, the Hi Pres-Ckt1 problem occurs.When the Hi Pres-Ckt1 problem occurs, the unit continues to operate but cooling circuit #1 is disabled. Circuit #1 remains disabled until both high pressure switches are closed and the Hi Pres-Ckt1 problem is manually cleared through the unit keypad or via a network signal.Hi Pres-Ckt2This alarm occurs on units equipped with compressorized cooling only. If either of the cooling circuit #2 high pressure switches (HP2 or HP4) opens (binary input CCB2-BI7 off) indicating a high refrigerant pressure situation, the Hi Pres-Ckt2 problem occurs.When the Hi Pres-Ckt2 problem occurs, the unit continues to operate but cooling circuit #2 is disabled. Circuit #2 remains disabled until both high pressure switches are closed and the Hi Pres-Ckt2 problem is manually cleared through the unit keypad or via a network signal.Lo Pres-Ckt1This alarm occurs on units equipped with compressorized cooling only. When a call is made for circuit #1 operation, if the cooling circuit #1 low pressure switch (LP1) remains open (input removed from CCB1-BI6) beyond a “low pressure time period” after the circuit #1 liquid line solenoid is opened, the Lo Pres-Ckt1 problem occurs. The alarm also

occurs any time the circuit is operating if LP1 opens. If the unit is configured for low ambient condenser operation and the OA Temp= parameter value is below 45°F, the “low pressure time period” is 165 seconds. Otherwise the “low pressure time period” is 45 seconds.When the Lo Pres-Ckt1 problem occurs, the unit continues to operate but cooling circuit #1 is disabled. Circuit #1 remains disabled for at least one cooling stage time period. After the cooling stage time period expires, the alarm automatically clears and the circuit is re-enabled. If the Lo Pres-Ckt1 problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal. Lo Pres-Ckt2This alarm occurs on units equipped with compressorized cooling only. When a call is made for circuit #2 operation, if the cooling circuit #2 low pressure switch (LP2) remains open (binary input CCB2-BI6 off) beyond a “low pressure time period” after the circuit #2 liquid line solenoid is opened, the Lo Pres-Ckt2 problem occurs. The alarm also occurs any time the circuit is operating if LP2 opens. If the unit is configured for low ambient condenser operation capability and the OA Temp= parameter value is below 45°F, the “low pressure time period” is 165 seconds. Otherwise the “low pressure time period” is 45 seconds.When the Lo Pres-Ckt2 problem occurs, the unit continues to operate but cooling circuit #2 is disabled. Circuit #2 remains disabled for at least one cooling stage time period. After the cooling stage time period expires, the alarm automatically clears and the circuit is re-enabled. If the Lo Pres-Ckt2 problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal. Frost-Ckt1This alarm occurs on units equipped with compressorized cooling without hot gas bypass operation only. If the circuit #1 frost protection switch (FP1) opens (binary input CCB1-BI8 off) while a compressor on cooling circuit #1 has been on for at least two minutes and the circuit #1 liquid line solenoid valve (SV1) is open, the Frost-Ckt1 problem occurs. This indicates a cold refrigerant temperature exists at the unit evaporator coil on circuit #1, creating the possibility of frost build-up on the coil.When the Frost-Ckt1 problem occurs, the unit continues to operate but cooling circuit #1 is disabled. Circuit #1 remains disabled for at least one cooling stage time period. After the cooling stage time period expires, the alarm automatically clears and the circuit is re-enabled. If the Frost-Ckt1 problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.

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Frost-Ckt2This alarm occurs on units equipped with compressorized cooling without hot gas bypass operation only. If the circuit #2 frost protection switch (FP2) opens (binary input CCB2-BI8 off) while a compressor on cooling circuit #2 has been on for at least two minutes and the circuit #2 liquid line solenoid valve (SV2) is open, the Frost-Ckt2 problem occurs. This indicates a cold refrigerant temperature exists at the unit evaporator coil on circuit #2, creating the possibility of frost build-up on the coil.When the Frost-Ckt2 problem occurs, the unit continues to operate but cooling circuit #2 is disabled. Circuit #2 remains disabled for at least one cooling stage time period. After the cooling stage time period expires, the alarm automatically clears and the circuit is re-enabled. If the Frost-Ckt2 problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal. Comp 1 AlmThis alarm occurs only on units equipped with compressorized cooling. If compressor #1 has been commanded on for longer than ten seconds and the compressor #1 input to the compressor control board is off (binary input CCB1-BI9 off), the Comp 1 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #1 input is delivered to the compressor control board through an auxiliary switch on the compressor #1 contactor. Therefore, precisely speaking, the alarm indicates that the controller commanded the compressor to start but the contactor did not pull in. When the unit is equipped with a compressor #1 oil pressure switch (OP1) and/or a compressor #1 external motor protector (MP1), this condition normally occurs when either MP1or OP1 trip. If the unit is equipped with neither MP1 nor OP1, this alarm simply indicates the contactor did not pull in for electrical or mechanical reasons.1

When the Comp 1 Alm problem occurs, the unit continues to operate but compressor #1 is disabled. Compressor #1 remains disabled for 35 minutes after which the alarm automatically clears and the compressor is re-enabled. The controller can then attempt to start compressor #1 again when required. If the Comp 1 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.

Note: The OP1 device itself requires a manual reset once it trips. The MP1 device automatically resets when the compressor motor windings cool.

Comp 2 AlmThis alarm occurs only on units equipped with compressorized cooling. If compressor #2 has been commanded on for longer than ten seconds and the compressor #2 input to the compressor control board is off (binary input CCB2-BI9 off), the Comp 2 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #2 input is delivered to the compressor control board through an auxiliary switch on the compressor #2 contactor. Therefore, precisely speaking, the alarm indicates that the controller commanded the compressor to start but the contactor did not pull in. When the unit is equipped with a compressor #2 oil pressure switch (OP2) and/or a compressor #2 external motor protector (MP2), this condition normally occurs when either MP2 or OP2 trip. If the unit is equipped with neither MP2 nor OP2, this alarm simply indicates the contactor did not pull in for electrical or mechanical reasons.1

When the Comp 2 Alm problem occurs, the unit continues to operate but compressor #2 is disabled. Compressor #2 remains disabled for 35 minutes after which the alarm automatically clears and the compressor is re-enabled. The controller can then attempt to start compressor #2 again when required. If the Comp 2 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.


Comp 3 AlmThis alarm occurs only on units equipped with compressorized cooling. If compressor #3 has been commanded on for longer than ten seconds and the compressor #3 input to the compressor control board is off (binary input CCB1-BI10 off), Comp 3 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #3 input is delivered to the compressor control board through an auxiliary switch on the compressor #3 contactor. Therefore, precisely speaking, the alarm indicates that the controller commanded the compressor to start but the contactor did not pull in. When the unit is equipped with a compressor #3 oil pressure switch (OP3) and/or a compressor #3 external motor protector (MP3), this condition normally occurs when either MP3 or OP3 trip. If the unit is equipped with neither MP3 nor OP3, this alarm simply indicates the contactor did not pull in for electrical or mechanical reasons1.When the Comp 3 Alm problem occurs, the unit continues to operate but compressor #3 is disabled. Compressor #3

1. Unit models 018 through 060 are equipped with scroll com-pressors. Unit models 070 and 075 are optionally equipped with scroll compressors. Oil pressure switches are not used on these units. Also, some scroll compressor sizes are equipped with internal motor protection. In these cases, external motor protectors are not used. These include Comp #1 on unit models 018 through 036, Comp #3 on unit models 025 through 036 and Comp2 on unit model 018.

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remains disabled for 35 minutes after which the alarm automatically clears and the compressor is re-enabled. The controller can then attempt to start compressor #3 again when required. If the Comp 3 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.


Comp 4 AlmThis alarm occurs only on units equipped with compressorized cooling. If compressor #4 has been commanded on for longer than ten seconds and the compressor #4 input to the compressor control board is off (binary input CCB2-BI10 is off), the Comp 4 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #4 input is delivered to the compressor control board through an auxiliary switch on the compressor #4 contactor. Therefore, precisely speaking, the alarm indicates that the controller commanded the compressor to start but the contactor did not pull in. When the unit is equipped with a compressor #4 oil pressure switch (OP4) and/or a compressor #4 external motor protector (MP4), this condition normally occurs when either MP4or OP4 trip. If the unit is equipped with neither MP4 nor OP4, this alarm simply indicates the contactor did not pull in for electrical or mechanical reasons1.When the Comp 4 Alm problem occurs, the unit continues to operate but compressor #4 is disabled. Compressor #4 remains disabled for 35 minutes after which the alarm automatically clears and the compressor is re-enabled. The controller can then attempt to start compressor #4 again when required. If the Comp 4 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.


Comp 5 AlmThis alarm occurs only on units equipped with compressorized cooling. If compressor # 5 has been on form longer than ten seconds and the compressor #5 input to the compressor control board is off (binary input CCB1-BI1 off), the Comp 5 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #5 input is delivered to the compressor control board through an auxiliary switch on the compressor #5 contactor. Therefore, precisely speaking, the alarm indicates that controller commanded the compressor to start but the contactor did not

pull in. This condition normally occurs when the external motor protector MP5 trips. When the Comp 5 Alm problem occurs, the unit continues to operate but compressor # 5 is disabled. Compressor # 5 remains disabled for 35 minutes after which the alarm automatically clears and the compressor is re-enabled. The controller can then attempt to start compressor #5 again when required. If the Comp 5 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.Comp 6 AlmThis alarm occurs only on units equipped with compressorized cooling. If compressor # 6 has been on form longer than ten seconds and the compressor #6 input to the compressor control board is off (binary input CCB2-BI1 off), the Comp 6 Alm problem occurs as long as the circuit is not off on a high pressure alarm. The compressor #6 input is delivered to the compressor control board through an auxiliary switch on the compressor #6 contactor. Therefore, precisely speaking, the alarm indicates that controller commanded the compressor to start but the contactor did not pull in. This condition normally occurs when the external motor protector MP6 trips. When the Comp 6 Alm problem occurs, the unit continues to operate but compressor # 6 is disabled. Compressor # 6 remains disabled for 35 minutes after which the alarm automatically clears and the compressor is re-enabled. The controller can then attempt to start compressor #6 again when required. If the Comp 6 Alm problem occurs three times between 2:00 a.m. of one day and 2:00 a.m. of the next, the alarm does not automatically clear the third time but must be manually cleared through the unit keypad or via a network signal.PumpDown-Ckt1This alarm occurs on units equipped with compressorized cooling only. If the cooling circuit #1 low pressure switch (LP1) fails to open (binary input CCB1-BI6 off) within 180 seconds of the initiation of a cooling circuit #1 pumpdown cycle, the PumpDown-Ckt1 problem occurs.When the PumpDown-Ckt1 problem occurs, the unit continues to operate but pump down operation is terminated and cooling circuit #1 is disabled. Circuit #1 remains disabled until the PumpDown-Ckt1 problem is manually cleared through the unit keypad or via a network signal.PumpDown-Ckt2This alarm occurs on units equipped with compressorized cooling only. If the cooling circuit #2 low pressure switch (LP2) fails to open (binary input CCB2-BI6 off) within 180 seconds of the initiation of a cooling circuit #2 pumpdown cycle, the PumpDown-Ckt2 problem occurs.When the PumpDown-Ckt2 problem occurs, the unit continues to operate but pump down operation is terminated

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and cooling circuit #2 is disabled. Circuit #2 remains disabled until the PumpDown-Ckt2 problem is manually cleared through the unit keypad or via a network signal.Ckt1 Clg EnaWhen a unit is equipped with compressorized cooling, the main control board (MCB) controls the cooling outputs on and receives cooling circuit input information from the circuit #1 compressor control board (CCB1) via an RS485 communication interface between the two boards. If the MCB board detects a loss of communication between the two boards there must be an external method for the MCB to command the CCB1 board to shut off the cooling on that circuit. On units equipped with an air-cooled condenser, this is accomplished with a “cooling enable” output from MCB (MCB-BO7) hard wired directly to a “cooling enable” input to the CCB1 board (CCB1-BI12).On units equipped with an evaporative condenser, this is accomplished indirectly with a “cooling enable” output from MCB (MCB-BO7) that turns the evaporative condenser sump pump on and an auxiliary switch on the pump contactor delivers the “cool enable” input to the CCB1 board (CCB1-BI12).If the MCB board is communicating with the CCB1 board and the “cooling enable” output from MCB is on but the “cooling enable” input to CCB1 remains off the Ckt1 Clg Ena problem will occur. This indicates either a problem with the evaporative condenser sump pump or the sump water level.When the Ckt1 Clg Ena problem occurs, cooling circuit #1 is disabled. Cooling circuit #1 remains disabled until the problem is corrected and the Ckt1 Clg Ena problem is manually cleared through the unit keypad or via a network signal.Ckt2 Clg EnaWhen a unit is equipped with compressorized cooling, the main control board (MCB) controls the cooling outputs on and receives cooling circuit input information from the circuit #2 compressor control board (CCB2) via an RS485 communication interface between the two boards. If the MCB board detects a loss of communication between the two boards there must be an external method for the MCB to command the CCB2 board to shut off the cooling on that circuit. On unit equipped with an air-cooled condenser, this is accomplished with a “cooling enable” output from MCB (MCB-BO7) hard wired directly to a “cooling enable” input to the CCB2 board (CCB2-BI12).On units equipped with an evaporative condenser, this is accomplish indirectly with a “cooling enable” output from MCB (MCB-BO7) that turns the evaporative condenser sump pump on and an auxiliary switch on the pump contactor delivers the “cool enable” input to the CCB2 board (CCB2-BI12).If the MCB board is communicating with the CCB2 board and the “cooling enable” output from MCB is on but the “cooling enable” input to CCB2 remains off the Ckt2 Clg Ena problem

will occur. This indicates either a problem with the evaporative condenser sump pump or the sump water level.When the Ckt2 Clg Ena problem occurs, cooling circuit #2 is disabled. Cooling circuit #2 remains disabled until the problem is corrected and the Ckt2 Clg Ena problem is manually cleared through the unit keypad or via a network signal.GenC Clg EnaWhen a unit is equipped with a DX cooling coil and is interfaced with a field supplied condensing unit; it is equipped with a generic condenser control board for controlling the field supplied condensing unit (GCB1). The main control board (MCB) controls the cooling outputs on the generic condenser control board via an RS485 communication bus interface between the two boards. If the MCB detects a loss of communication there must be an external method for the MCB to command the GCB1 board to shut off the cooling. This is accomplished with a “cooling enable” output from MCB (MCB-BO7) hard wired to a “cooling enable” input to the GCB1 board (binary input GCB1-BI12).If the MCB is communicating with the GCB1 board and the “cooling enable” output from MCB is on but the “cooling enable” input to GCB1 remains off, indicating a wiring problem between the boards, the GenC Clg Ena problem occurs.When the GenC Clg Ena problem occurs, cooling is disabled. Cooling remains disabled until the problem is corrected and the GenC Clg Ena problem is manually cleared through the unit keypad or via a network signal.HtgB Htg EnaWhen a unit is equipped with multi-stage electric heat, it is equipped with an electric heat control board for controlling the heat (EHB1). The main control board (MCB) controls the heating outputs on the electric heat control board via an RS485 communication bus interface between the two boards. If the MCB detects a loss of communication there must be an external method for the MCB to command the EHB1 board to shut off the heating. This is accomplished with a “heating enable” output from MCB (MCB-BO11) hard wired to a “heating enable” input to the EHB1 board (EHB1-BI12).If the MCB is communicating with the EHB1 board and the “heating enable” output from MCB is on but the “heating enable” input to EHB1 remains off, indicating a wiring problem between the boards, the HtgB Htg Ena problem occurs.When the HtgB Htg Ena problem occurs, heating is disabled. Heating remains disabled until the problem is corrected and the HtgB Htg Ena problem is manually cleared through the unit keypad or via a network signal.Ckt1 Comm FailWhen a unit is equipped with compressorized cooling, the main control board (MCB) controls the cooling outputs on

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and receives cooling circuit input information from the circuit #1 compressor control board (CCB1) via an RS485 communication bus interface between the two boards. If the MCB detects a loss of communication between the two boards, the Ckt1 Comm Fail problem occurs.When the Ckt1 Comm Fail problem occurs while the unit is not in the Cooling operating state, the unit is allowed to enter the Cooling operating state as long as the MCB is communicating with the circuit #2 cooling control board (CCB2). In this case the cooling capacity is limited to that available from circuit #2. If the MCB is not communicating with either cooling control board (CCB1 or CCB2), the unit is not allowed to enter the Cooling operating state.When the Ckt1 Comm Fail problem occurs while the unit is in the Cooling operating state, the unit remains in the Cooling operating state. However, the maximum cooling capacity is limited to that of circuit #2 if the MCB is communicating with the circuit #2 cooling control board (CCB2). If the MCB is not communicating with either cooling control board (CCB1 or CCB2), the current cooling capacity in the MCB is set to 0%. Any cooling that may be operating at the time of the communication failure remains on (on either circuit) until the MCB leaves the Cooling operating state due to normal operation. When the MCB leaves the Cooling operating state the “cooling enable” output (MCB-BO7) is turned off and, therefore, the “cooling enable” input to the CCB1 and CCB2 boards is removed (binary inputs CCB1-BI12 and CCB2-BI12 off) and this causes the CCB1 and CCB2 to completely stage off all cooling. The MCB then does not re-enter the Cooling operating state until communication is re-established with at lease one cooling control board. When communications between the MCB and CCB1 is re-established, the Ckt1 Comm Fail problem automatically clears.Ckt2 Comm FailWhen a unit is equipped with compressorized cooling, the main control board (MCB) controls the cooling outputs on and receives cooling circuit input information from the circuit #2 compressor control board (CCB2) via an RS485 communication bus interface between the two boards. If the MCB detects a loss of communication between the two boards, the Ckt2 Comm Fail problem occurs.When the Ckt2 Comm Fail problem occurs while the unit is not in the Cooling operating state, the unit is allowed to enter the Cooling operating state as long as the MCB is communicating with the circuit #1 cooling control board (CCB1). In this case the cooling capacity is limited to that available from circuit #1. If the MCB is not communicating with either cooling control board (CCB1 or CCB2), the unit is not allowed to enter the Cooling operating state.When the Ckt2 Comm Fail problem occurs while the unit is in the Cooling operating state, the unit remains in the Cooling operating state. However, the maximum cooling capacity is limited to that of circuit #1 if the MCB is

communicating with the circuit #1 cooling control board (CCB1). If the MCB is not communicating with either cooling control board (CCB1 or CCB2), the current cooling capacity in the MCB is set to 0%. Any cooling that may be operating at the time of the communication failure remains on (on either circuit) until the MCB leaves the Cooling operating state due to normal operation. When the MCB leaves the Cooling operating state the “cooling enable” output (MCB-BO7) is turned off and, therefore, the “cooling enable” input to the CCB1 and CCB2 boards is removed (binary inputs CCB1-BI12 and CCB2-BI12 off) and this causes the CCB1 and CCB2 to completely stage off all cooling. The MCB then does not re-enter the Cooling operating state until communication is re-established with at lease one cooling control board. When communications between the MCB and CCB2 is re-established, the Ckt2 Comm Fail problem automatically clears.GenC Comm FailWhen a unit is equipped with a DX cooling coil and is interfaced with a field supplied condensing unit; it is equipped with a generic condenser control board (GCB1) for controlling the field supplied condensing unit. The main control board (MCB) controls the cooling outputs on the generic condenser control board via an RS485 communication bus interface between the two boards. If the MCB detects a loss of communication between the two boards, the GenC Comm Fail problem occurs.When the GenC Comm Fail problem occurs while the unit is not in the Cooling operating state, the unit is not allowed to enter the Cooling operating state.When the GenC Comm Fail problem occurs while the unit is in the Cooling operating state, the unit remains in the Cooling operating state. However, the current cooling capacity in the MCB is set to 0%. Any cooling that may be operating at the time of the communication failure remains on until the MCB leaves the Cooling operating state due to normal operation. When the MCB leaves the Cooling operating state the “cooling enable” output (MCB-BO7) is turned off and, therefore, the “cooling enable” input to the GCB1 board is removed (binary input GCB1-BI12 off) and this causes the GCB1 to completely stage off all cooling. The MCB then does not re-enter the Cooling operating state until communication is re-established with the cooling control board (GCB1). When communications between the MCB and GCB1 is re-established, the GenC Comm Fail problem automatically clears.HtgB Comm FailWhen a unit is equipped with multi-stage electric heat, it is equipped with an electric heat control board for controlling electric heat (EHB1). The main control board (MCB) controls the heating outputs on the electric heat control board via an RS485 communication bus interface between the two boards. If the MCB detects a loss of communication between the two boards, the HtgB Comm Fail problem occurs.

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When the HtgB Comm Fail problem occurs while the unit is not in a heating operating state, the unit is not allowed to enter the a heating operating state.When the HtgB Comm Fail problem occurs while the unit is in a heating operating state, the unit remains in the heating operating state. However, the current heating capacity in the MCB is set to 0%. Any heating that may be operating at the time of the communication failure remains on until the MCB leaves the Heating operating state due to normal operation. When the MCB leaves the heating operating state the “heating enable” output (MCB-BO11) is turned off and, therefore, the “heating enable” input to the EHB1 board is removed (binary input EHB1-BI12 off) and this causes the EHB1 to completely stage off all heating. The MCB then does not re-enter any heating operating state until communication is re-established with the cooling control board (EHB1). When communications between the MCB and EHB1 is re-established, the HtgB Comm Fail problem automatically clears.ERecB Comm FailWhen a unit is equipped with an energy recovery wheel, it is equipped with an energy recovery control board for controlling the energy recovery wheel (ERB1). The main control board (MCB) controls the energy recovery outputs on the energy recovery control board via an RS485 communication bus interface between the two boards. If the MCB detects a loss of communication between the two boards, the ERecB Comm Fail problem occurs.When the ERecB Comm Fail problem occurs, the energy recovery system is disabled. When communications between the MCB and EHB1 is re-established, the ERecB Comm Fail problem automatically clears.

WarningsAirflow SwitchIf the unit has been in the Off operating state for at least thirty minutes and the PC7 airflow switch input to the main controller indicates airflow (binary input MCB-BI6 on), the Airflow Switch warning occurs. This normally indicates a problem with the PC7 airflow switch.When the Airflow Switch warning occurs, unit operation is not affected. When the alarm condition is corrected, the Airflow Switch warning must be manually cleared through the unit keypad or via a network signal.Dirty FilterIf the pressure drop across the first filter section in the unit exceeds the setting of the PC5 differential pressure switch while the unit is operational, the dirty first filter input is removed from MCB (binary input MCB-BI9 off) and the Dirty Filter warning occurs.When the Dirty Filter warning occurs, unit operation is not affected. The Dirty Filter warning must be manually cleared through the unit keypad or via a network signal.

Dirty FnlFltrIf the pressure drop across the final filter section in the unit exceeds the setting of the PC6 differential pressure switch while the unit is operational, the dirty final filter input is removed from MCB (binary input MCB-BI10 off) and the Dirty FnlFltr warning occurs.When the Dirty FnlFltr warning occurs, unit operation is not affected. The Dirty FnlFltr warning must be manually cleared through the unit keypad or via a network signal.Ckt1 H/WWhen a unit is equipped with compressorized cooling, the main control board (MCB) controls the cooling outputs on and receives cooling circuit input information from the circuit #1 compressor control board (CCB1) via an RS485 communication interface between the two boards. If the MCB board detects a loss of communication between the two boards there must be an external method for the MCB to command the CCB1 board to shut off the cooling on that circuit. On unit equipped with an air-cooled condenser, this is accomplished with a “cooling enable” output from MCB (MCB-BO7) hard wired directly to a “cooling enable” input to the CCB1 board (CCB1-BI12).On units equipped with an evaporative condenser, this is accomplished indirectly with a “cooling enable” output from MCB (MCB-BO7) that turns the evaporative condenser sump pump on and an auxiliary switch on the pump contactor delivers the “cool enable” input to the CCB1 board (CCB1-BI12).If the MCB board is communicating with the CCB1 board and the “cooling enable” output from MCB is off but the “cooling enable” input to CCB1 remains on the Ckt1 H/W warning will occur. This indicates either a wiring problem between boards or a problem with the evaporative condenser sump pump.When the Ckt1 H/W warning occurs, unit operation is not affected. The Ckt1 H/W warning must be manually cleared through the unit keypad or via a network signal.Ckt2 H/WWhen a unit is equipped with compressorized cooling, the main control board (MCB) controls the cooling outputs on and receives cooling circuit input information from the circuit #2 compressor control board (CCB2) via an RS485 communication interface between the two boards. If the MCB board detects a loss of communication between the two boards there must be an external method for the MCB to command the CCB2 board to shut off the cooling on that circuit. On unit equipped with an air-cooled condenser, this is accomplished with a “cooling enable” output from MCB (MCB-BO7) hard wired directly to a “cooling enable” input to the CCB2 board (CCB2-BI12).On units equipped with an evaporative condenser, this is accomplished indirectly with a “cooling enable” output from

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MCB (MCB-BO7) that turns the evaporative condenser sump pump on and an auxiliary switch on the pump contactor delivers the “cool enable” input to the CCB2 board (CCB2-BI12).If the MCB board is communicating with the CCB2 board and the “cooling enable” output from MCB is off but the “cooling enable” input to CCB2 remains on the Ckt2 H/W warning will occur. This indicates either a wiring problem between boards or a problem with the evaporative condenser sump pump.When the Ckt2 H/W warning occurs, unit operation is not affected. The Ckt2 H/W warning must be manually cleared through the unit keypad or via a network signal.GenC H/WWhen a unit is equipped with a DX cooling coil and is interfaced with a field supplied condensing unit; it is equipped with a generic condenser control board for controlling the field supplied condensing unit (GCB1). The main control board (MCB) controls the cooling outputs on the generic condenser control board via an RS485 communication bus interface between the two boards. If the MCB detects a loss of communication there must be an external method for the MCB to command the GCB1 board to shut off the cooling. This is accomplished with a “cooling enable” output from MCB (MCB-BO7) hard wired to a “cooling enable” input to the GCB1 board (binary input GCB1-BI12).

If the MCB is communicating with the GCB1 board and the “cooling enable” output from MCB is off but the “cooling enable” input to GCB1 remains on, indicating that the “cooling enable” input to the GCB1 board is “stuck” on, the GenC H/W warning occurs.When the GenC H/W warning occurs, unit operation is not affected. The GenC H/W warning must be manually cleared through the unit keypad or via a network signal.HtgB H/WWhen a unit is equipped with multi-stage electric heat, it is equipped with an electric heat control board for controlling the heat (EHB1). The main control board (MCB) controls the heating outputs on the electric heat control board via an RS485 communication bus interface between the two boards. If the MCB detects a loss of communication there must be an external method for the MCB to command the EHB1 board to shut off the heating. This is accomplished with a “heating enable” output from MCB (MCB-BO11) hard wired to a “heating enable” input to the EHB1 board (EHB1-BI12).If the MCB is communicating with the EHB1 board and the “heating enable” output from MCB is off but the “heating enable” input to EHB1 remains on, indicating that the “heating enable” input to the EHB1 board is “stuck” on, the HtgB H/W warning occurs.When the HtgB H/W warning occurs, unit operation is not affected. The HtgB H/W warning must be manually cleared through the unit keypad or via a network signal.

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MicroTech II DDC FeaturesThe MicroTech II unit controller uses PID control algorithms (referred to as “PID objects”) to control modulating output devices in order to keep a controlled variable at or near the desired set point. These devices are generally either floating-point actuators or variable frequency motor drives (VFD). There is a pair of outputs defined for each modulating device to be controlled. One output energizes to increase the capacity and the other energizes to decrease the capacity of the modulating device. There are two different PID controls schemes used to control the modulating output devices. These are the “Direct PID Method” and the “Cascaded PID Method.” The “Direct PID Method” uses one Velocity PID object to directly control the modulating device outputs. The “Cascaded PID Method” uses one Position PID and one Velocity PID object in a “cascaded” manner to control the modulating device outputs.

Direct PID MethodIn some cases, the controller uses a Velocity PID object directly to turn actuator control outputs on and off to maintain a controlled variable at a set point. In these cases the set point and current value of the controlled variable are input to the Velocity PID object. The Velocity PID object determines a “time on” for either the increase or decrease output as necessary to reduce the “error” between the set point and the controlled variable. This information is input into a position adjust output object (PAO) which in turn commands the output device increase or decrease output on and off, repositioning the actuator.

Note: In this method, position feedback from the control actuators is not used for control purposes.

Table 73 on page 127 lists the modulating devices controlled using this method. Figure 20 is a schematic representation of this control scheme.

Cascaded PID MethodIn some cases, the controller uses actuator position (or VFD speed) feedback and a combination of a Position PID object and a Velocity PID object to control actuator (or VFD) control outputs to maintain a controlled variable at a set point. In this “cascaded” control scheme, the set point and the current value of the controlled variable are input to the Position PID object. The Position PID object then calculates a new actuator position (or VFD speed) set point and inputs this into the Velocity PID object. The Velocity PID object then compares the current actuator position (or VFD speed) feedback signal to the new position set point and determines a “time on” for either the increase or decrease output as necessary to maintain the feedback signal at the current position (or speed) set point. This information is input into a position adjust output object (PAO) which in turn commands the output device increase or decrease output on and off, repositioning the actuator (or changing VFD speed).Table 73 on page 127 lists the modulating devices controlled using this method. Figure 21 is a schematic representation of this control scheme.

Figure 20: Direct PID Method Control Scheme

Figure 21: Cascaded PID Method Control Scheme

+-

Velocity PID

ControlledVariable

Set Point PAOActuatorPosition

+-

Velocity PID

ControlledVariable

Set Point PAOActuator orVFD Position

+-

Position PID

Actuator Position (or VFD Speed) Feedback

126 OM-137-2

PID Control ParametersAssociated with each modulating output device, there is a set of three adjustable PID control parameters. These are the Period, Proportional Band and Integral Time.

Note: Since derivative control is not generally required in HVAC control strategies, the Derivative Time parameter of the PID object is set to 0 and is not adjustable through the unit keypad/display. The Derivative Time parameter can only be adjusted using the MicroTech II Service Tool.

Since the factory settings for these parameters should provide the best control action, field changes are not recommended. If problems arise, these parameters should first be set back to the factory settings if they have been changed in the field. If adjustment is then required, caution should be used since parameters grossly out of adjustment can cause erratic unit operation and possible equipment damage. Changes should only be made in small increments and to only one parameter at a time. After each change, enough time for the system to stabilize should be allowed before further changes are made. Refer to the following sections for guidelines regarding how the specific parameters affect the control action of the PID algorithm.

PeriodUnless grossly misadjusted, changing the Period parameter generally has a relatively small effect on the PID control action. It should generally be set to a value of the same magnitude and within 1/4 to 2/3 the time constant of the system being controlled. If the Period is set too long, loss of system control will likely occur. If the Period is set too short, dramatic system “hunting” will likely occur. When in doubt, this parameter should be set to the factory default setting.

Note: The Period parameter is not allowed to be set higher than the Integral Time parameter. If this is

attempted the Period parameter reverts to its previ-ous setting.

Proportional Band and Integral TimeThe Proportional Band and the Integral Time parameters have a similar effect on the PID control action. Increasing either the Proportional Band or the Integral Time has a slowing effect on the control action. Decreasing either the Proportional Band or the Integral Time has a speeding effect on the control action. Increasing or decreasing both parameters at the same time has a more dramatic slowing or speeding effect. Increasing one while decreasing the other tends to have countering effects on the control action. Therefore, if it becomes necessary to slow down or speed the control action, these two parameter should generally not both be changed at the same time. One parameter should remain unchanged while the other is increased or decreased. Proper “tuning” of the Proportional Band and the Integral Time parameters involves finding an acceptable “balance” between the two.

Note: The Integral Time parameter is not allowed to be set lower than the Period parameter. If this is attempted the Integral Time parameter reverts to its previous setting.

Adjusting PID Control ParametersCorrecting System Instability (“Hunting”)If the system control is unstable (“hunting”), this generally means the control response is too “fast.” To correct system “hunting”, generally the first step is to slow down the response by increasing the Integral Time until the system becomes stable. This may, however, cause “sluggishness” in the controlled variable approach to the set point during transient conditions (such as at unit start up).1 If system “sluggishness” occurs after the Integral Time is adjusted, it means the overall control response is now too “slow”. The

Table 73: MicroTech II Modulating Output Devices

Modulating Device Decrease Binary Output Increase Binary Output PID Method Controlled Variable

Hot Water Valve Actuator MCB-BO9 MCB-BO10 Direct Discharge Temperature

Steam Valve Actuator MCB-BO9 MCB-BO10 Direct Discharge Temperature

Gas Valve Actuator MCB-BO9 MCB-BO10 Direct Discharge Temperature

Chilled Water Valve Actuator MCB-BO7 MCB-BO8 Direct Discharge Temperature

Heating F&BP Actuator MCB-BO9 MCB-BO10 Direct Discharge Temperature

Cooling F&BP Actuator MCB-BO7 MCB-BO8 Direct Discharge Temperature

Economizer Damper Actuator MCB-BO5 MCB-BO6 Cascaded Discharge Temperature

Discharge Fan Inlet Vane Actuator or VFD MCB-BO13 MCB-BO14 Cascaded Duct Static Pressure

Return/Exhaust Fan Inlet Vane Actuator or VFD MCB-BO15 MCB-BO16 Cascaded Building Static Pressure

OM-137-2 127

response can be speeded up by reducing the Proportional Band. When the Proportional band is changed so that the controlled variable approach to the set point is acceptable, it may then be necessary to readjust the Integral Time to re-stabilize the control action.When in doubt, these parameters should be set to the factory default setting.

Correcting System “Sluggishness”If the system control is “sluggish”, meaning in the controlled variable approach to the set point during transient conditions (such as at unit start up) is too slow, this generally means the overall control response is too “slow.”1 To correct system “sluggishness”, the first step is to speed up the overall system response by decreasing the Proportional Band so that the controlled variable approach to the set point is acceptable. This may, however, result in system instability (“hunting”). If system instability occurs, the Integral Time should be increased to slow down the control response and stabilize the control action.When in doubt, these parameters should be set to the factory default setting.

PRAC Tuning

In the event that PID parameters do need adjustment, an automatic tuning function called PRAC (pattern recognition

adaptive control) is available for several of the MicroTech II control loops. These PRAC functions can be used in lieu of manually adjusting the various PID proportional band and integral time control parameters.To use the PRAC feature to tune the duct static pressure control PID parameters, for example, change the Duct Static Pressure Control PRAC Flag from No to Yes. Then allow the unit to control the duct static pressure in the normal manner. The PRAC function requires a “history” and it may take several excursions (perhaps as many as 10) above and below set point for the new proportional band and integral settings to be determined and for the control to settle out.

Note: After using the PRAC function, the new propor-tional band and integral settings do not appear on the unit keypad until power is subsequently cycled to the unit controller.

1. Once operating, the system can be checked for sluggish-ness by changing the set point and measuring the time it takes for the controlled variable to reach the set point.

1. Once operating, the system can be checked for sluggish-ness by changing the set point and measuring the time it takes for the controlled variable to reach the set point


Keypad/Display ID Parameter Name

Menu Name Menu Item

Duct Static P Setup PRAC= No Duct Static Pressure Control PRAC Flag

Bldg Static P Setup PRAC= No Building Static Pressure Control PRAC Flag

Chilled Water Setup PRAC= No Chilled Water Control PRAC Flag

Economizer Setup PRAC= No Economizer Control PRAC Flag

Heating Setup PRAC= No Heating Control PRAC Flag

CAUTIONGrossly misadjusting PID parameters can cause erratic unit operation and equipment damage.

PID control parameters should only be adjusted by trained personnel having a thorough under-standing of how the parameters affect overall system operation. Generally these parameters do not need to be adjusted from the factory default settings.

128 OM-137-2

Software Identification and Configuration

Software IdentificationThe MicroTech II control system code is made up of up to four different software components. All unit applications include a main control board application code component that resides in the main control board (MCB). Then, depending on the unit configuration, there may be one or two cooling auxiliary control boards, an electric heat auxiliary control board or an energy recovery auxiliary control board each loaded with an application code component. The application code in the main control board and any auxiliary control boards are each assigned a ten-digit software identification number. This includes a seven-digit base number, followed by a three-digit version number. The software identification numbers that the unit was loaded with at the factory can be determined from a software identification label on the back of the door panel on which the keypad/display is mounted. Figure 22 shows a typical software identification label. The box labeled “UNIT SOFTWARE NUMBER” contains the software identification number for the code in the main controller (MCB). The box labeled “COMPRESSOR SOFTWARE” contains the software identification number for the code in the auxiliary cooling control board(s) (CCB1, CCB2 and GCB1) when applicable. The box labeled “STAGE ELEC HEAT SOFTWARE” contains the software identification number for the code in the auxiliary electric heat control board (EHB1) when applicable. The box labeled “ENERGY RECOVERY SOFTWARE” contains the software identification number for the code in the auxiliary energy recovery control board (ERB1) when applicable. Identifying Application Code Using Unit Keypad/DisplayThe software identification number for the application currently loaded into the main control board (MCB) can be determined by viewing the AHU ID= parameter in the Unit Configuration menu on the unit keypad/display. The entire 10 digit “UNIT SOFTWARE NUMBER” is displayed.The software identification number for the application currently loaded into the CCB1 and CCB2 auxiliary cooling control boards can be determined by viewing the CCB1 ID= and CCB2 ID= parameters in the Unit Configuration menu on the unit keypad/display. Only the 6th through 9th positions of the “COMPRESSOR SOFTWARE” identification number are displayed. For example if a CCB1 board was loaded with version 2506011310 compressor board software, then the CCB1 ID= parameter would display “1131”. If a unit is not equipped with CCB1 and CCB2 boards, the CCB1 ID= and CCB2 ID= parameters will display “???”.The software identification number for the application currently loaded into the GCB1 auxiliary cooling control

board can be determined by viewing the GCB1 ID= parameter in the Unit Configuration menu on the unit keypad/display. Only the 6th through 9th positions of the “COMPRESSOR SOFTWARE” identification number are displayed. For example if a GCB1 board was loaded with version 2506012210 compressor board software, then the GCB1 ID= parameter would display “1221”. If a unit is not equipped with a GCB1 board, the GCB1 ID= parameter will display “???”.The software identification number for the application currently loaded into the EHB1 auxiliary electric heat control board can be determined by viewing the EHB1 ID= parameter in the Unit Configuration menu on the unit keypad/display. Only the 6th through 9th positions of the “STAGE ELEC HEAT SOFTWARE” identification number are displayed. For example if a EHB1 board was loaded with version 2506012210 electric heat board software, then the EHB1 ID= parameter would display “1221”. If a unit is not equipped with a EHB1 board, the EHB1 ID= parameter will display “???”.The software identification number for the application currently loaded into the ERB1 auxiliary energy recovery control board can be determined by viewing the ERB1 ID= parameter in the Unit Configuration menu on the unit keypad/display. Only the 6th through 9th positions of the “ENERGY RECOVERY SOFTWARE” identification number are displayed. For example if a ERB1 board was loaded with version 2506013210 energy recovery board software, then the ERB1 ID= parameter would display “1321”. If a unit is not equipped with a ERB1 board, the ERB1 ID= parameter will display “???”.

Figure 22: Software Identification Label

UNIT SOFTWARE NUMBER

SOFTWARE CONFIGURTION CODE

COMPRESSOR SOFTWARE

STAGE ELEC HEAT SOFTWARE

ENERGY RECOVERY SOFTWARE

UNIT G.O.-SEQ NUMBER

2506010146

11780030411002210100211YYY

2506011310

2506012210

2506013210

728121-050

OM-137-2 129

Main Control Board (MCB) ConfigurationAfter the main control board software component is loaded into the MCB, it must be “configured” for the specific control application. This consists of setting the value of 20 configuration variables within the MCB. These variables define things such as the type of cooling, number of compressors and cooling stages and the type of heat. If all of these items are not set appropriately for the specific unit, the unit will not function properly. The correct settings for these parameters are defined for a given unit by the unit “Software Configuration Code”. The “Software Configuration Code” consists of a 26-character string of numbers and letters. The code can be found on the unit Software Identification Label located on the back side of the door upon which the keypad display is mounted. This label is shown in Figure 22. Only the first 22 characters of this code are used for software configuration purposes.

The first 22 characters of the Software Configuration Code currently loaded into a unit controller can be determine via the unit keypad/display by viewing the six menu items under the Configuration Code menu. The six menu items are Pos # 1-4=, Pos # 5-8=, Pos # 9-12=, Pos # 13-16=, Pos # 17-20= and Pos # 21-22=. The Software Configuration Code in the unit is determined by combining the values of these six parameters. For example, if the six parameters read as follows: Pos # 1-4=1.178, Pos # 5-8=0.030, Pos # 9-12=4.104, Pos # 13-16=0.221, Pos # 17-20=0.100 and Pos # 21-22=2.0, then the Software Configuration Code in the unit is 1178003041040221010020. Note that the decimal points in the values are ignored when constructing the code.Table lists these 22 configuration code variables including the position with in the string, description of the parameter and the applicable settings for each. The software default values are shown in bold font.

Software Configuration CodeConfiguration Code Position Description Values (Default in Bold)

1 Unit Type

0 RA Zone Control1 RA DAT Control2 100 OA Zone Control3 100 OA DAT Control

2 Cooling Type

0 None1 Compressorized Clg2 Chilled Water (2 Wire FB)A Chilled Water (3 Wire FB)

3 Compressorized Cooling Configuration

0 2 Comp/2 Stage1 2 Comp/3 Stage2 2 Comp/4 Stage3 2 Comp/6 Stage4 3 Comp/4 Stage5 4 Comp/4 Stage6 6 Comp/6 Stage7 4 Comp/8 Stage8 Generic Condenser

4 Generic Condenser Stages 1 – 8 Stages (Default = 8)

5 Low Ambient 0 No1 Yes

61 Condenser Fan Type

0 - No Evap Cond Control1 - 2 Cond Fans/Cir - ABB VFDs 22 - 2 Cond Fans/Cir - Graham VFDs 3 - 2 Cond Fans/Cir - Reliance VFDs4 - 2 Cond Fans/Cir - No VFDs5 - 3 Cond Fans/Cir - ABB VFDs6 - 3 Cond Fans/Cir - Graham VFDs7 - 3 Cond Fans/Cir - Reliance VFDs8 - 3 Cond Fans/Cir - No VFDs

7 Damper Type

0 None1 Single Position 30% (2 Wire FB)2 Single Position 100% (2 Wire FB)3 Economizer (2 Wire FB)A Single Position 30% (3 Wire FB)B Single Position 100% (3 Wire FB)C Economizer (3 Wire FB)

130 OM-137-2

1. When downloading code into a unit controller, this position must be 0 if the unit is not equipped with an evaporative condenser. This is true even if the unit Software Identifi-cation Label indicates something other than 0.

Main Control Board (MCB) Data ArchivingAll MCB control parameters and the real time clock settings are backed up by the MCB battery when power is removed from the MCB. In the event of a battery failure, the MCB

includes a data archiving function. Once a day, just after midnight, all the MCB control parameter settings are archived to a file stored in the MCB FLASH memory. If the MCB is powered up with a low or defective battery (or with the battery removed), the most recently archived data is restored to the controller.

8 Design Flow

0 No DesignFlo1 018-030 (800) (Non-Precision PS)2 036-040 (802) (Non-Precision PS)3 045-075 (047) (Non-Precision PS)4 080-135 (077) (Non-Precision PS)A 018-030 (800) (Precision PS)B 036-040 (802) (Precision PS)C 045-075 (047) (Precision PS)D 080-135 (077) (Precision PS)

9 Heating Type

0 None1 F BP Ctrl2 Multi Staged3 Modulated Gas, 3 – 1 (2 Wire FB)4 Modulated Gas, 20 – 1 (2 Wire FB)5 Steam or Hot Water (2 Wire FB)6 Single Stage Gas7 Single Stage ElectricA Modulated Gas, 3 – 1 (3 Wire FB)B Modulated Gas, 20 – 1 (3 Wire FB)C Steam or Hot Water (3 Wire FB)

10 Max Heating Stages 1 – 8 Stages (Default = 1)11,12 & 13 Max Heat Rise Three Digits (Default = 100)

14 Discharge Fan Type0 Constant Volume1 Variable Inlet Vanes2 Variable Freq Drive

15 Return Fan Type

0 Constant Volume1 Variable Inlet Vanes2 Variable Freq Drive3 No Return Fan4 Propeller Exhaust

16 Return/Exhaust Fan Capacity Control Method

0 None1 Tracking2 Bldg Press3 Position

17 Second Pressure Sensor Type0 None1 Duct2 Bldg

18 Entering Fan Temp Sensor 0 No1 Yes

19 Energy recovery0 None1 Constant Speed Wheel2 Variable Speed Wheel

20 Final Filter 0 No1 Yes

21 Heating Configuration0 Draw Through Preheat1 Draw Through Reheat2 Blow Through

22 Cooling Configuration 0 Draw Through1 Blow Through

Software Configuration Code (Continued)Configuration Code Position Description Values (Default in Bold)

OM-137-2 131

Note: When this archived data restoration process occurs, it increases the controller start up and initialization time period by approximately 75 seconds.

132 OM-137-2

TroubleshootingIn general, when a unit is not operating as expected, the first step in troubleshooting the MicroTech II control system should always be to determine the current operating state and then determine why the unit is currently in that operating state. The current operating state is determined via the unit keypad by viewing the UnitStatus= parameter in the System

menu. Once the current operating state is determined, it then can be assessed whether or not the control is operating correctly in that state and if not why. The following sections discuss various scenarios and some steps for troubleshooting them.

Table 75: Fans Operate After Normal Startup Sequence But:

Problem Check

1. Unit does not leave Fan Only and enter the Econo or Cooling operat-ing state.

1.1. Check Clg Status= parameter in System menu:1. The unit does not enter the Econo operating state unless the Clg Status=

parameter indicates “All Clg” or “Econo.” If it does, refer to Item 1.2 below.

2. The unit does not enter the Cooling operating state unless the Clg Sta-tus= parameter indicates “All Clg” or “Mech Clg.” If it does, refer to Item 1.2 below.

3. The unit does not enter the Econo or the Cooling operating state if the Clg Status= parameter indicates something other than “All Clg”, “Econo” or “Mech Clg.” If this is the case, refer to “Clg Status” on page 50 to determine the reason.

1.2. Compare the Ctrl Temp= parameter to the Eff Clg Spt= parameter in the Zone Cooling menu.1. The unit does not enter the Econo or Cooling operating state unless the

current value of the Ctrl Temp= parameter is above the Eff Clg Spt= by more than half the Clg Deadband= parameter in the Zone Cooling menu. If it is, refer to Item 1.3 below.

2. If the current value of the Ctrl Temp= parameter is not above the Eff Clg Spt= by more than half the Clg Deadband= parameter in the Zone Cool-ing menu, the Eff Clg Spt= parameter must be adjusted accordingly to enable cooling operation. Refer to “Heat/Cool Changeover” on page 75.

1.3. Compare the current value of the Disch Air= parameter to the Eff Clg Spt= parameter in the Discharge Cooling menu.1. The unit does not initially enter the Econo or Cooling operating state

unless the current value of the Disch Air= parameter is above the Eff Clg Spt= by more than half the Clg Db= parameter in the Discharge Cooling menu. If it is and the unit still does not enter either the Econo or Cooling operating state, MCB is likely defective.

2. If the current value of the Disch Air= parameter is not above the Eff Clg Spt= by more than half the Clg Db= parameter in the Discharge Cooling menu, the Eff Clg Spt= parameter must be adjusted accordingly to acti-vate cooling operation. Refer to “Economizer” on page 78, “Cooling: Multistage” on page 82, or “Cooling: Modulating” on page 92 (as appli-cable).

OM-137-2 133

2. Unit does not leave Fan Only and enter Heating operating state.

2.1. Check Htg Status= parameter in System menu:1. The unit does not enter the Heating operating state unless the Htg Sta-

tus= parameter indicates “Htg Ena”. If it does, refer to Item 2.2 below.2. The unit does not enter the Heating operating state if the Htg Status=

parameter indicates anything other than “Htg Ena.” If this is the case, refer to “Htg Status” on page 51 to determine the reason.

2.2. Compare the Ctrl Temp= parameter to the Eff Htg Spt= parameter in the Zone Heating menu.1. The unit does not enter the Heating operating state unless the current

value of the Ctrl Temp= parameter is below the Eff Htg Spt= by more than half the Htg Deadband= parameter in the Zone Heating menu. If it is and the unit is equipped with multi-stage or modulating heat, refer to Item 2.3 below. If it is and the unit is equipped with single-stage heat and the unit still does not enter the Heating operating state, MCB is likely defective.

2. If the Ctrl Temp= is not below the Eff Htg Spt= by more than half the Htg Deadband= parameter in the Zone Heating menu, the Eff Htg Spt= parameter must be adjusted accordingly to enable heating operation. Refer to “Heat/Cool Changeover” on page 75

2.3. If the unit is equipped with multi-stage or modulating heat, compare the cur-rent value of the Disch Air= parameter to the Eff Htg Spt= parameter in the Discharge Heating menu.1. The unit does not initially enter the Heating operating state unless the

current value of the Disch Air= parameter is below the Eff Clg Spt= by more than half the Htg Db= parameter in the Discharge Heating menu. If it is and the unit still does not enter the Heating operating state, MCB is likely defective.

2. If the current value of the Disch Air= parameter is not below the Eff Htg Spt= by more than half the Htg Db= parameter in the Discharge Heating menu, the Eff Htg Spt= parameter must be adjusted accordingly to acti-vate heating operation. Refer to “Heating: Multistage” on page 94 or “Heating: Modulating” on page 96 (as applicable).

Table 75: Fans Operate After Normal Startup Sequence But: (Continued)

Problem Check

134 OM-137-2

Table 76: Unit Does Not Startup and Run at All:

Problem Check

1. Unit does not leave the Off Unoc operat-ing state. (UnitStatus= parameter in the System menu indicates “Off Unoc” and unit does not start.)

1.1. Check Occupancy= parameter in Occupancy menu:1. If the Occupancy = parameter in the Occupancy menu indicates

either “Occ” or “Bypass” and the unit remains in the Off Unoc operating state, MCB is likely defective

2. If the Occupancy = parameter in the Occupancy menu indicates “Unocc” refer to Item 1.2 below.

1.2. Check Occ Mode= parameter in the Occupancy menu:1. If the Occ Mode= parameter is set to “Unocc”, the unit starts only

if unoccupied heating (night setback) or unoccupied cooling (night setup or purge) operation is active. Refer to “Unoccupied Control” on page 114.

2. If the Occ Mode= parameter is set to “Auto”, the unit starts only if at least one of the following are true:a) Field time clock terminals 101 to 102 on TB2 in the main con-

trol box are made (binary input MCB-BI1 is on). Refer to “External Time Scheduling” on page 59.

b) Internal time schedule indicates an occupied period. Refer to “Internal Daily Scheduling” on page 56.

c) Holiday time schedule indicates an occupied period. Refer to “Holiday Scheduling” on page 58.

d) One event schedule indicates an occupied period. Refer to “One Event Scheduling” on page 58.

e) Network time schedule indicates an occupied period. Refer to “Network Time Scheduling” on page 59.

f Unoccupied heating (night setback) or unoccupied cooling (night setup or purge) operation is active. Refer to “Unoccu-pied Control” on page 114.

If any one of items a) through f) is true and the Occupancy= parameter in the Occupancy menu still indicates “Unocc” and the unit remains in the “Off Unoc” operating state, MCB is likely defective.

2. Unit does not leave the Off Sw operating state. (UnitStatus= parameter in the Sys-tem menu indicates “Off Sw” and unit does not start.)

2.1. Check terminals 101 and 104 on TB2 in the main control box:1. The unit is disabled and remains in the Off Sw operating state

when terminal 101 is made to 104 on TB2 (binary input MCB-BI2 is on).

2. If terminal 101 is not made to 104 on TB2 (binary input MCB-BI2 is off) and the UnitStatus= parameter continues to indicated “Off Sw”, MCB is likely defective.

OM-137-2 135

3. Unit does not leave the Off Net operating state. (UnitStatus= parameter in the Sys-tem menu indicates “Off Net” and unit does not start.)

3.1. Check Ctrl Mode= parameter in System menu:1. If the Ctrl Mode= parameter in System menu is set to anything

other than “Auto” and the UnitStatus= parameter in the System menu continues to indicate “Off Net”, refer to Item 3.2.

2. If the Ctrl Mode= parameter in System menu is set to “Auto”, the UnitStatus= parameter indicates “Off Net” when the Appl Mode= parameter in the System menu is set to “Off.” If the Appl Mode= indicates something other than “Off” and the UnitStatus= parame-ter in the System menu continues to indicate “Off Net”, refer to Item 3.2.

3.2. Check Emerg Override= parameter in Occupancy menu:1. The UnitStatus= parameter indicates “Off Net” when the Emerg

Override= parameter is set to “Off.”2. If the Emerg Override= parameter is set to “Norm” and the Unit-

Status= parameter continues to indicate “Off Net”, MCB is likely defective.

4. Unit does not leave the Off Alm operat-ing state. (UnitStatus= parameter in the System menu indicates “Off Alm” and unit does not start.)

4.1. Press the ALARM key on the unit keypad to Check Active Alarm 1 menu:1. If the Active Alarm 1 menu indicates an active “fault”, the alarm

condition must be corrected and the “fault” cleared before unit can be started.

2. If the Active Alarm 1 menu indicates “None” or an alarm type other than a “fault” and the UnitStatus= parameter in the System menu continues to indicate “Off Alm”, MCB is likely defective.

5. Unit does not leave the Off Man operat-ing state. (UnitStatus= parameter in the System menu indicates “Off Man” and unit does not start.)

5.1. Check Ctrl Mode= parameter in System menu:1. If the Ctrl Mode= parameter in System menu is set to “Off”, the

UnitStatus= parameter indicates “Off Man.” The Ctrl Mode= parameter must be set to something other than “Off” before the unit will start.

2. If the Ctrl Mode= parameter in System menu is set to anything other than “Off” and the UnitStatus= parameter in the System menu still indicates “Off Man”, MCB is likely defective.

Table 76: Unit Does Not Startup and Run at All: (Continued)

Problem Check

136 OM-137-2

Table 77: Unit Does Not Shut Off:

Problem Check

1. Occupancy = parameter in Occupancy menu indicates “Occ” and unit does not shut off.

1.1. Check Terminals 101 to 102 on TB2 in the main control box:1. The Occupancy= parameter in Occupancy menu indicates “Occ”

and the unit runs continuously if the field time clock terminals 101 to 102 on TB2 in the main control box are made (binary input MCB-BI1 is on). If 101 to 102 are not made, refer to Item 1.2.

1.2. Check the Occ Mode= parameter in System menu:1. The Occupancy= parameter in Occupancy menu indicates “Occ”

and the unit runs continuously if the Occ Mode= parameter in Sys-tem menu is set to “Occ”.

2. The Occupancy= parameter in Occupancy menu indicates “Occ” and the unit runs if the Occ Mode= parameter in Occupancy menu is set to “Auto” and any one of the following are true:a) Internal time schedule indicates an occupied period.b) Holiday schedule indicates an occupied period.c) One event schedule indicates an occupied period.d) Network time schedule indicates an occupied period. If none

of the items a), b), c) or d) above are true and the Occupancy= parameter in Occupancy menu continues to indicate “Occ”, check the OccSrc= parameter in the Occupancy menu. If this parameter indicates “Int Sched”, refer to item 3 below. If not, the MCB is likely defective.

3. Check the Time=, Day= and Date= parameters in the in the Time/Date menu. Set the current day's time schedule in the Daily Schedule menu to 08:00 - 16:00. Set the Time= parameter to 15:58:00. Let the Time= parameter roll past the 16:00 stop time. The unit should shut off. If it does, set the current day schedule back to the desired value and set the Time= parameter to the correct time. If the unit still does not shut off, the MCB is likely defective.

OM-137-2 137

2. Occupancy= parameter in Occupancy menu indicates “Unocc” and unit does not shut off.

2.1. Check the UnoccHtg Spt= parameter in the Zone Heating menu:1. If following conditions are all true, the unit starts and runs in the

unoccupied heating mode with the Occupancy= parameter in Occupancy menu indicating “Unocc”:a) The Space Sensor= parameter in the Unit Configuration menu

is set to “Yes.”b) The UnoccHtg Spt= parameter in the Zone Heating menu is

set to a value greater than 0°F.c) The current Space Temp= value is or was below the UnoccHtg

Spt= parameter in the Zone Heating menu and has not risen above the UnoccHtg Spt= by more than the UnoccHtgDiff= parameter in the Zone Heating menu.

If any of the items a), b) or c) above are not true and the unit con-tinues to run while the Occupancy= parameter in Occupancy menu indicates "Unocc", refer to Item 2.2.

2.2. Check the UnoccClg Spt= parameter in the Zone Cooling menu:1. If following conditions are all true, the unit starts and runs in the

unoccupied cooling mode with the Occupancy= parameter in Occupancy menu indicating “Unocc”:a) The Space Sensor= parameter in the Unit Configuration menu

is set to “Yes.”b) The UnoccClg Spt= parameter in the Zone Cooling menu is

set to a value less than 99°F.c) The current Space Temp= value is or was below the UnoccClg

Spt= parameter in the Zone Cooling menu and has not dropped below the UnoccClg Spt= parameter by more than the UnoccClgDiff= parameter in the Zone Cooling menu.

If any of the items a), b) or c) above are not true and the unit con-tinues to run while the Occupancy= parameter in Occupancy menu indicates “Unocc”, MCB is likely defective.

Table 77: Unit Does Not Shut Off: (Continued)

Problem Check

138 OM-137-2

OM-137-2 139

This document contains the most current product information as of this printing. For the most up-to-dateproduct information, please go to www.mcquay.com.

© 2004 McQuay International • www.mcquay.com • 800-432-1342

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