RTU and Chiller Maintenance

for Maximum EfficiencyMay 28, 2015

Meet Your Panelists

Working to deliver the energy you need, whenever you need it.

That’s our Promise to Michigan.

2

• Mike Carter

• Justin Kale

• Subject Matter Experts:

o David MacDonald , Marketing Manager,

Business Energy Efficiency Programs

o Phil Walsh, Corporate Account Manager

3

• HVAC basics

• RTU maintenance

• Chiller basics

• Chiller maintenance

o Compressor

o Evaporator/Condenser

o Economizers

o Air HandlersSource: NREL

Table of Contents

4Poll Questions

• Do you have a formal proactive

chiller/RTU maintenance program

in place?

a) Yes

b) No

c) Not sure

5Maintenance Basics

• Proactive/preventive versus reactive

• Predictive maintenance

o Based on actual performance

o Log books are important

• RTU trends

• Chillers

o Refrigerant temperatures and pressures

o Condenser-water entering and leaving temperatures

o Chilled-water entering and leaving temperatures

o Run times for automatic refrigerant purge units

o Real-time monitoringSource: www.sxc.hu

6Maintenance Basics

• What are signs of maintenance issues?

o Deformation

o Discoloration

o Oxidation

o Corrosion

o Scale

o Leakage of fluid or vapor

o Excessive noise/vibration

o Loose/missing fasteners

o Ice buildup

o Frost or condensate

o Worn or damaged insulating

materials

7Maintenance Basics

• Root Cause Analysis

Man

• The actions of personnel

Method

• A process or procedure

Machine

• Specific piece of equipment or tool

Materials

• Consumables

Measurement

• How data is generated or used

Mother Nature

• Abnormal environmental effectsSource: Mark Orge, Canadian Facility Management & Design

8HVAC Basics

• Power (Capacity)

o Motor power (kW) = Horsepower x 0.746/efficiency X LF

• A 12 hp motor = 12 hp x 0.746/0.9 = 8.85 kW

• 1 kW = 3,412 Btu/hr

9Packaged Rooftop Units (RTU)

Image courtesy of Daikin Applied

Gas heatersEvaporator Condenser

Compressor

Filter rackExhaust fan

ControlsEconomizerDampers

Plenum fan

10Packaged Rooftop Units (RTU)

• RTU maintenance study

o 20-ton RTU for mall in South Carolina

• 7-day per week operation

• Service /repair costs of $14,348

o Undetected failure of one condenser fan

o Compressor replacement

o Thermostatic-expansion-valve (TXV) failure

o Installed in 2003 and serviced in 2013

o Instrumented from 2010-2013

• 45 refrigerant and air sensors

2003 2010 % 2014

IEER Efficiency 11.2 7.8 - 30% 9.5

Power demand 23.7 kW 30.3 kW + 28% 25.3

11Packaged Rooftop Units (RTU)

• RTU maintenance study

o Service energy savings

of $1,870 per year

o Projected preventive maintenance

results (2003 to 2010)

$8,400 added energy cost of deferred maintenance

$5,600 cost of preventive maintenance

$2,800 energy cost savings (50% ROI)

o Would also avoid occupant complaints

12Packaged Rooftop Units (RTU)

• Preventive maintenance priorities

1. Cleaning the condenser coil.

2. Verifying operation of the condenser fan(s).

3. Adjusting refrigerant charge.

4. Verifying proper economizer operation.

5. Checking compressor discharge temperature.

6. Testing compressor oil for the presence of acid.

7. Testing high- and low-pressure cutout switches.

8. Adjusting the thermostatic expansion valve (TXV).

9. Checking and adjusting the blower belt.Source: West & Beaufort, Advan Tek Consulting

13Packaged Rooftop Units (RTU)

• Preventive maintenance – Bi-annual

Source: West & Beaufort, AdvanTek Consulting in HPAC Engineering

14Packaged Rooftop Units (RTU)

• Preventive maintenance - Annual

Source: West & Beaufort, AdvanTek Consulting in HPAC Engineering

15Packaged Rooftop Units (RTU)

Cleaning RTU coils

o If the evaporator airflow is restricted

by 36%, the capacity drop is 20%.

• This changes the 3-ton unit to a 2.5-ton unit.

o On the other hand, when the condenser

coils are 50% restricted, the capacity

drops only 11%.

• Blocked condenser coils can increase condensing

temperature by 8ºF to 10ºF resulting in a 6% to 8%

increase in power consumption.

Source: Coil-Tech used with permission

16Packaged Rooftop Units (RTU)

Cleaning RTU coils

o Cleaning methods

• Spraying high-pressure (<600 psi)

cold water

• Surface dirt and debris can be

removed using a stiff bristle brush

or wire brush.

o DO NOT use any detergents with

microchannel condenser coils.

Source: SpeedClean, Inc.

17Packaged Rooftop Units (RTU)

• Fan and belts

18Packaged Rooftop Units (RTU)

• Fan and belts

o Manually rotate the fan(s) to ensure free movement.

o Check motor bearings for wear.

o Do not stretch new belts over the pulley sheaves

• Loosen belt tensioner

o Use a Browning or Gates tension gauge

(or equivalent) to adjust the belt tension.

• Recheck the belt tension at least twice

during the first 2 to 3 days of operation.

• Belt tension may decrease until the new

belts are “run in”.Source: Gates Corporation

19Packaged Rooftop Units (RTU)

• Refrigerant sight glass

o Moisture content of the refrigerant

o Liquid refrigerant is present

• Frothing means shortage

o Green = good (dry)

o Yellow = caution

Source: J&E Hall International

20Poll Questions

• Which of the following is the leading

source of fan drive problems?

a) Improper installation

b) Environmental factors (heat, dirt)

c) Improper drive maintenance

d) Poor drive design

21Chiller Basics

• Chiller components

Source: EERE

22

• Efficiency ratingso One ton (12,000 Btu/hr) equals 3.516 kW at 100% efficiency

o Coefficient of Performance (COP)

COP = Rated Cooling Output, kBtuh / Rated electrical input, kBtuh

o Full Load Value (FLV)

FLV = kW/ton efficiency rating

COP = 3.516 (kW/ton) / FLV (kW/ton)

o Energy Efficiency Ratio (EER)

EER = Cooling output (Btuh) / Electricity consumed (watt)

EER = 12,000 Btuh per ton / FLV (watt per ton)

EER = COP x 3.413

o Application Part Load Value (APLV)

• Other than full load

o Integrated Part Load Value (IPLV)

• Weighted average of full load and part load

FLV

(kW/ton)

COP EER

0.6 5.9 20

0.75 4.7 16

1.0 3.5 12

1.5 2.3 8

Chiller Basics

23Chiller Maintenance

1. Maintain a daily log

2. Perform an oil and refrigerant analysis

3. Keep evaporator and condenser tubes clean

4. Ensure a leak-free unit

5. Maintain proper water treatment

Source: Darin Fackler, Hill York Service

Source: ORNL

24Chiller Compressor Maintenance

• Visual check of compressor oil

o Oil level

o Color (darker is worse)

o Change oil on large systems once

a year and clean particles from case

• Have the condition of your system fluid checked by a

qualified lab, a minimum of four times per year

• Monitor for refrigerant leaks

• Inspect journal and thrust bearings and drive gears

25

• Check the motor terminals for pitting,

corrosion, or loose connections

• Check electrical contactors for

corrosion or pitting

• Check amp draws on all motor loads

• Check the crankcase heaters for

proper operation

• Periodically analyze refrigerant for

moisture, acid, and rust

• Ensure that the pipe insulation is dry

and not broken off.

Source: New York Power Authority

Chiller Compressor Maintenance

26Chiller Compressor Maintenance

• Centrifugal chillers

o Guide vane linkage assembly

and drive mechanism

o Guide vane control shaft seal

• Reciprocating machines

o Compressor suction and

discharge valves.

• Check for high vibration on a

capillary line (causes leaks)

and secure all vibrating lines.

Source: John Tomczyk,

Ferris State University

Source: Atlas Copco Airpower

27

• Take superheat and subcooling temperature

readings to obtain the chiller's maximum efficiency.

• Check for tube corrosion

o Eddy current testing can

identify internal pitting,

freeze damage, cracks,

and wear

o Remove the sludge with

bristle brushes on the end

of long metal rods.

o If badly fouled, use chemicals

Source: Maverick Inspection Ltd.

Chiller Evaporator/Condenser Maintenance

28

• Clean debris and dirt from water tower condenser

and unclog spray nozzles, especially in the spring.

o Clean pre-strainers

o Spray should be uniform

• Clean condenser coils

o A 1/32” scale buildup results in a

7% reduction in energy efficiency

Chiller Water-side Maintenance

Source: Baltimore Aircoil Company

29

Source: M360 Energy

• Apply proper water filtering

Chiller Water-side Maintenance

• How familiar are you with our energy efficiency programs?

• How familiar are you with our specialized Business Customer Care team and dedicated Business Center?

a) Very familiar

b) Somewhat familiar

c) Not very familiar

d) Not at all familiar

Poll Question 30

31

• Check cold water basin

o Pump leaks or obstructions

o Clean sump strainer

• If atmosphere is extremely dirty,

it may be necessary to clean strainer weekly

o Check and adjust bleed rate

o Make-up water valve is working

o Heater controls are working

• Clean debris and dirt from water tower

condenser and unclog spray nozzles,

especially in the spring.

o Clean pre-strainers

o Spray should be uniform

Chiller Water-side Maintenance

Source: Baltimore Aircoil Company

32

• Install water gauges so you can see

pressure drops; particularly through

the evaporator.o Water supplied to the unit should have a minimum

differential pressure of 15 psi at the chiller

• Check for proper water flowo Overflow can cause vibration, damaging

the copper tubes.

o Put a bypass valve on the end of the

pipe run going to the chillers.

o Keep chilled water flow rate between

3 to 12 feet per second.

Source: Denver Water

Chiller Water-side Maintenance

33

• Check fan belt for proper

tension and any belt wear or

improper alignment.

• Check fan bearings and

lubricate, if necessary.

• Check belt tension and adjust.

• For gear drives, check oil level.

• Clean strainer

o If atmosphere is extremely

dirty, it may be necessary to

clean strainer weekly. Source: Virginia Department of Mines, Minerals, and Energy

Chiller Water-side Maintenance

34

• Re-enabling economizers

o Address any outstanding

performance issues

• Maintain the calibration of

enthalpy sensors

• Measure the difference between

the indoor and outdoor pressure

during economizer operation

o Avoid building over-pressurization

o Relief air system must have an

adequate airflow path

Chiller Economizer Maintenance

35

• Verify that the outside air sensor is

in a good, representative location

o Never in direct sun; not too close

to air outlets

• Make sure the mixed air

sensors are located

correctly as well

o In a place with good mixing

Source: energycodes.gov

Chiller Economizer Maintenance

36Chiller Air Handler Maintenance

• Cycle your dampers open and

closed periodically

o Avoid stuck dampers

• Adjust actuators to achieve full

damper closure

o Close gaps

• Worn for blade and jamb seals.

• Grease serviceable (not sealed)

blower shaft bearings

Source: Dave Moser, CLEAResult

37Wide Variety of Incentives From Consumers Energy

• VFD on HVAC Fans and CW Pumps: $40-60/hp

• High Efficiency air conditioners and chillers: $30-40/Ton

• Air-Side Economizer: $15/Ton

• Chilled Water Reset Retrofit : $1 - $1.50/Ton

• Demand Control Ventilation : $.02-.04/sq.ft.

• Ductwork Insulation: $3-$6/ft.

To find a business energy efficiency incentive that works for

you, contact Consumers Energy at 877-607-0737.

38Tune-Up/Maintenance Incentives

• Boilers

o Up to $500 per boiler

• Furnaces/RTU’s

o Up to $125 per unit

• Chillers

o $350 per chiller

• Steam traps

o $140 per trap

39Poll Question

• How valuable has this Webinar been to you?

a) Not valuable at all.

b) Slightly valuable

c) Moderately valuable.

d) Very valuable.

e) Extremely valuable.

40Resources

• Standard Practice for Inspection

and Maintenance of Commercial

Building HVAC Systems

(ANSI/ASHRAE/ACCA Standard

180-2012).

Questions?

Working to deliver the energy you need, whenever you need it. That’s our Promise to Michigan.

41

• Resources For You Sign up for our FREE Solution Center eNewsletter

• Ask an Expert

• Tools, calculators and energy-saving tips

• All available online

• Contact Us Website: www.ConsumersEnergy.com/business

Phone: 800-805-0490

Email: businesscenter@consumersenergy.com