Installation andMaintenance Data

Bulletin No. IM 268-6March 1995

Part No. 585558Y

SeasonPak@Packaged Air Cooled Water Chiller

Models ALR 035DThru 185D

01995 McQuay International

Table of Contents

IntroductionGeneral Description ....................................................... 3Nomenclature ................................................................ 3Inspection ...................................................................... 3

InstallationHandling.. ....................................................................... 3Location ......................................................................... 4Service Access .............................................................. 4Vibration Isolators.. .................................................... 4, 5Water Piping .................................................................. 6Flow Switch ....... . ... . ....................................................... 7Water Connections ........................................................ 7Refrigerant Charge ........................................................ 7Glycol Solutions ......................................................... 7-8Evaporator Water Flow and Pressure Drop ........ ....... 8

Physical Data .............................................................. 9-12Major Components ...................................................... 13

Dimensional Data ..................................................... 14-16

Field WiringElectrical Data Single Point ................................... 17-l 8Electrical Data Multiple Point ................................ 19-21Voltage Limitations ............................................ . . ..... 21Compressor and Condenser Fan Motors ............. 22-23Customer Wiring Information ................................ 24-26Typical Field Wiring Diagram.. ..................................... 27

Unit Layout and Principles of OperationMajor Component Locations.. ..................................... 28Control Center ....................................................... 28-29Disconnect Location .................................................... 29Electrical Legend ......................................................... 30Sequence of Operation ............................................... 31

Start-up and ShutdownPre Start-up ................................................................. 32Start-up ........................................................................ 32Temporary Shutdown .................................................. 32Start-up After Temporary Shutdown.. ......................... 32Extended Shutdown .................................................... 33

System MaintenanceGeneral.. ....................................................................... 33Fan Motor Bearings ..................................................... 33Electrical Terminals.. .................................................... 33Compressor Oil Level .................................................. 33Oil Equalization ............................................................ 33Condensers.. ................................................................ 34Refrigerant Sightglass ................................................. 34Lead-Lag ...................................................................... 34

ServiceFilter-Driers .................................................................. 34Liquid Line Solenoid Valve .......................................... 34Thermostatic Expansion Valve .................................... 35Evaporator ................................................................... 35

In Warranty Return Material ProcedureCompressor ................................................................. 36Components Other Than Compressors ...................... 36

AppendixStandard Controls

Thermostat .............................................................. 37Control Band ........................................................... 37Oil Pressure Safety Control .............................. 37-38High Pressure Control ............................................ 38Low Pressure Control ............................................. 38Compressor Lockout .............................................. 38Compressor Motor Protector ................................. 38FanTroll Head Pressure Control .............................. 39

Optional ControlsSpeedTroll Head Pressure Control ......................... 40High Ambient Control ............................................. 40High Return Water Control ..................................... 41Low Ambient Start .................................................. 41Freeze Control ........................................................ 41Part Winding Start.. ................................................. 41Phase/Voltage Monitor ..................................... 41-42Hot Gas Bypass ...................................................... 42

Controls, Settings and Functions ........................... 43-44

Troubleshooting Chart ............................................. 45-46

Product Warranty ........................................................... 46

See freeze protection references under the heading “Water Piping” on pages 6 and 13.

“FanTrol,” “McQuay.” “ SeasonPak” and “SpeedTrol” are registered trademarksof McQuay International, Minneapolis, Minnesota, USA.

“Bulletin Illustrations cover the general appearance of McQuay International products at the time ofpublication and we reserve the right to make changes in design and construction at anytime without notice.”

Page 2 / IM 268

IntroductionGeneral Description

McQuay type SeasonPak air cooled water chillers are com-plete, self-contained automatic refrigerating units that in-clude the latest in engineered components arranged toprovide a compact and efficient unit. Each unit is completelyassembled and factory wired before evacuation, chargingand testing, and comes complete and ready for installation.Each unit consists of twin air cooled condensers with integralsubcooler sections, multiple accessible hermetic compres-sors, replaceable tube dual circuit shell-and-tube evapora-tor, and complete refrigerant piping. Liquid line componentsthat are included are manual liquid line shutoff valves, sight-glass/moisture indicators, and double diaphragm hydraulicelement thermal expansion valves. Other features include

compressor crankcase heaters, an evaporator heater forchilled water freeze protection, limited pumpdown during“on” or “off” seasons, compressor lead-lag switch to alter-nate the compressor starting sequence, and sequencedstarting of compressors.

The electrical control center includes all safety and oper-ating controls necessary for dependable automatic opera-tion. Condenser fan motors are fused in all three conductorlegs and started by their own three-pole contactors. Com-pressors are not fused but may be protected by optionalcircuit breakers, or bythe field installed fused disconnect forprotection.

Nomenclature

Reciprocating Compressors

InspectionWhen the equipment is received all items should be carefullychecked against the bill of lading to insure a completeshipment. All units should be carefully inspected for damageupon arrival. All shipping damage must be reported to thecarrier and a claim must be filed with the carrier. The unitserial plate should be checked before unloading the unit to

be sure that it agrees with the power supply available.Physical damage to unit after acceptance is not the respon-sibility of McQuay.

Note: Unit shipping and operating weights areavailable inthe Physical Data tables on pages 9 through 12.

InstallationNote: Installation and maintenance are to be performedonly by qualified personnel who are familiar with localcodes and regulations, and experienced with this type of

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equipment.Sharp edges and coil surfaces are a potential injuryhazard Avoid contact with them.

HandlingCare should be taken to avoid rough handling or shock due moving as this may result in serious damage.to dropping the unit. Do not push or pull the unit from any- To lift the unit, 2-1/2” (64mm) diameter lifting holes arething other than the base, and block the pushing vehicle provided in the base of the unit. Spreader bars and cablesaway from the unit to prevent damage to the sheet metal should be arranged to prevent damage to the condensercabinet and end frame (see Figure 1).

Never allow any part of the unit to fall during unloading or

Figure 1. Suggested pushing arrangement

coils or unit cabinet (see Figure 2).

Figure 2. Suggested lifting arrangement

Blocklng Required/ -Across Full Width

Spreader BarsRecommended

(Use CautIonI

Note: Number of fans canvary from this diagram. butlifting method remains thesame.

(Note Control Box LocatIon)

IM 268 / Page 3

LocationCare should be taken in the location of the unit to provideproper airflow to the condenser, minimizing effects on con-densing pressure.

Figure 3. Clearance requirements

Due to the vertical condenser design of the ALR 110through 185 chillers, it is recommended that the unit isoriented to that prevailing winds blow parallel to the unitlenght, thus minimizing the effects on condensing pressure.If it is not practical to orient the unit in this manner, a winddeflector should be constructed.

Minimizing clearances as shown in Figure 3 will preventmost discharge air recirculation to the condenserwhich willhave a significant effect on unit performance.

;I-~-:_1

Table 7. Clearances

Au? WJIT SIZE “X” DHWENION035D - 070D 8 ft. (2438mm) Min.

085D - 185D 10 ft. (3048mm) Min.

Notes:1. Minimum clearance between units is 1’2 ft. (3658mm).2. Units must not be installed in a pit that IS deeper than the height of the unit.3. Minimum clearance on each side is 12 ft. (3658mm) when installed w a pit.

Service AccessEach end of the unit must beaccessible after installation for assembly should be removed for service.periodic service work. Compressors, filter-driers, and manual The fan blade and fan motor rain shield must be removedliquid line shutoff valves are accessible on each side of the for access to wirinq terminals at the top of the motor.unit adjacent to the control box. High pressure, low pressure,and motor protector controls are on the compressor.Freezestats and cooler barrel thermostats are nearthecooler.Most other operational, safety and starting controls arelocated in the unit control box.

On all ALR units the condenser fans and motors can beremoved from the top of the unit. A complete fan/motor

Disconnect all power to the unit while servicing con-denser fan motors. Failure to do so may cause bodilyinjury or death.

Vibration IsolatorsVibration isolators are recommended for all roof mountedinstallations or wherever vibration transmission is a consid-eration. Table 2 lists spring isolators for all ALR unit sizes.Figure4 shows isolator locations in relation to the unit controlcenter. Figure 5 gives dimensions that are required to secure

Table 2. Vibration isolators (spring) Table 3. Spring flex isolators

10ID

ICPl-31 (CPl-31 (CPl-31 /CPl-31 (CPi-31 (CPl-31

1 CPl-32 1 CPl-32 1 CPl-32 1 CPl-32 1 CPl -32 1 CPI -32

J

CPZ-28 CP2-28 CP2-31 CP2-28 CP2-28 CP2-31CP2-31 CP2-31 CP2-32 CP2-31 CPZ-31 CP2-32CP2-31 CP2-32 CP2-32 CP2-31 CP2-32 CP2-32

L1300135D CP2-31 CP2-32 CP2-32 CP2-32 CP2-31

14!H3 CP2-31 CP2-32 CP4-27 CP2-32 CP2-31

?soD CP2-32 CP2-32 CP4-27 CP2-32 CPZ-32

1650 CP4-27 CP2-32 CP2-32 CP4-27 CP2-32 CP2-32

17Cm CP4-27 CP2-32 CP2-32 CP4-27 CP2-32 CP2-32

1950 CP4-27 CP2-32 CP2-32 CP4-27 CP2-32 CP2-32

each McQuay isolator selection to the mounting surface.Table 4 shows the isolator loads at each location in Figure 4,and the maximum loads for each McQuay selection areshown in Table 3.

Page 4 I IM 268

Water PipingDue to the variety of piping practices, it is advisable to follow 10. The total quantity of water in the system should bethe recommendations of local authorities. They can supply sufficient to prevent frequent “on-off” cycling. The totalthe installer with the proper building and safety codes re- quantity of water, in the system, turnover rate should notquired for a safe and proper installation. be less than 15 minutes.

Basically, the piping should be designed with a minimumnumber of bends and changes in elevation to keep systemcost down and performance up. It should contain:

11. In the event glycol is added to the water system, as anafterthought for freeze protection, recognize that therefrigerant suction pressure will be lower, cooling per-formance less, and water side pressure drop is greater.If the percentage of glycol is large, or if propylene isemployed instead of ethylene glycol, the added pres-sure drop and loss of performance could be substantial.Reset the freezestat and low leaving water alarm tem-peratures. The freezestat is factory set to default at 36°F(2.2%). Reset the freezestat setting to approximately 4”to 5°F (2.3” to 2.8%) below the leaving chilled watersetpoint temperature. See the section titled “GlycolSolutions” for additional information concerning glycol.

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Vibration eliminatorstoreducevibrationand noisetrans-mission to the building.

Shutoff valves to isolate the unit from the piping systemduring unit servicing.

Manual or automatic air vent valves at the high points ofthe system. Drains should be placed at the lowest pointsin the system.

Some means of maintaining adequate system waterpressure (e.g., expansion tank or regulating valve).

Temperature and pressure indicators located at the unitto aid in unit servicing.

A strainer or some means of removing foreign matterfrom the water before it enters the pump. It should beplaced far enough upstream to prevent cavitation at thepump inlet (consult pump manufacturer for recommen-dations). The use of a strainer will prolong pump life andthus keep system performance up.

A strainer should also be placed in the water lines justprior to the inlets of the evaporator and condenser. Thiswill aid in preventing foreign material from entering anddecreasing the performance of the evaporator.

The shell-and-tube cooler has a thermostat and heatingcable to prevent feeze-up, due to low ambient, down to-20°F (-29°C). It is suggested that the heating cable bewired to a separate 11 OV supply circuit. As shipped fromthe factory, it is factory wired to the control circuit. Anywater piping to the unit must also be protected toprevent feezing.

If the unit is used as a replacement chiller on a previouslyexisting piping system, the system should bethoroughlyflushed prior to unit installation and then regular wateranalysis and chemical water treatment on the evapora-tor and condenser is recommended immediately atequipment start-up.

Figure 7. Typical field evaporator water piping

If a separate disconect is used for the 110V supply tothe cooler heating cable, it should be clearly markedso that it is not accidentally shut off during coldseasons.

Prior to insulating the piping and filling the system, apreliminary leak check should be made.

Piping insulation should include a vapor barrierto preventmoisture condensationand possible damage to the buildingstructure. It is important to have the vapor barrier on theoutside of the insulation to prevent condensation within theinsulation on the cold surface of the pipe.

Figure 6. ALR evaporator

J 1

III

1L T-

Vibration Lf

Eliminator Water GateV a l v e

Note: Chilled water piping should be insulated.Strainer

awitch Balancing GateValve Valve

PressureGauge

Page 6 / IM 268

Flow SwitchA water flow switch must be mounted in either the enteringor leaving water line to insure that there will be adequatewater flow and cooling load to the evaporator before the unitcan start. This will safeguard against slugging the compres-sors on startup. It also serves to shut down the unit in theevent that water flow is interrupted to guard against evapo-rator freeze-up.

A flow switch is available from McQuay under orderingnumber 00175033-00. It is a “paddle” type switch and

adaptable to any pipe size from 1” (25mm) to 6” (152mm)nominal. Certain minimum flow rates are required to closethe switch and are listed in Table 6. Installation should be asshown in Figure 8. Electrical connections in the unit controlcenter should be made at terminals 5 and 6. The normallyopen contacts of the flow switch should be wired betweenthese two terminals. There is also a set of normally closedcontacts on the switch that could be used for an indicatorlight or an alarm to indicate when a “no flow” condition exists.

Table 6. Flow switch minimum flow rates Figure 8.

2% ( 63.5) 24.30 (1.50)

3 ( 76.2) 30.00 (1.90)

4 (101.6) 39.70 (2.50)

5 (127.0) 58.70 (3.70)6 (152.4) 79.20 k5.00)

L5’ (127mm) Dia.Min. After Switch

L 5’ (127mm) Pipe Dia.Min. Before Switch

Note: Water pressure differential switches are not recommended for outdoorapplications.

Water Connections

Water piping to thecooler can be brought up from the bottomof the unit or through the side between the vertical supports.The dimensional data on pages 14 through 16 give thenecessary dimensions and locations for all piping connec-tions.

Note: On units sizes 150D through 185D there is a dia-gonal bracket off of a vertical support which will interfere withthe water connection if brought in from the side. This bracecan be removed, but only after the unit is in place.

Refrigerant ChargeAll units are designed for use with Refrigerant 22 and areshipped with an operating charge. The operating charge for

each unit is shown in the Physical Data tables on pages 9through 12.

Glycol Solutions

The system glycol capacity, glycol solution flow rate in gpm,and pressure drop through the cooler may be calculatedusing the following formulas and table.

Note: The procedure below does not specify the type ofglycol. Use thederatefactors found in Table 7 for correctionswhen using ethylene glycol and those in Table 8 for propy-lene glycol.

1. Capacity - Cooling capacity is reduced from that withplain water. To find the reduced value multiply the chiller’swater system tonnage by the capacity correction factor Cto find the chiller’s capacity in the glycol system.

2. Flow -To determine evaporator gpm (or AT) knowing AT(or gpm) and capacity:

Glycol gpm = 24 x capacity (glycol)AT

x G (from table)

For Metric Applications -To determine evaporator Ips(or AT) knowing AT (or Ips) and kW:

Glycol Ips = kW4.18 x AT

x Flow (from table)

Pressure drop -To determine pressure drop throughthe cooler, when using glycol, enter the water pressuredrop curve on page8 at the actual glycol gpm. Multiply thewater pressure drop found there by P to obtain correctedglycol pressure drop.

To determine glycol system kW, multiply the water systemkW by factor K.

Test coolant with a clean, accurate glycol solution hy-drometer (similar to that found in service stations) to deter-mine the freezing point. Obtain percent glycol from thefreezing point table below. On glycol applications it is nor-mally recommended by the supplier that a minimum of 25%solution by weight be used for protection against corrosion.

Do not use an automative grade antifreeze. Industrialgrade glycols must be used. Automotive antifreezecontains inhibitors which will cause plating on thecopper tubes within the chiller evaporator. The typeand handling of glycol used must be consistent withlocal codes.

IM 268 / Page 7

Field WiringWiring must comply with all applicable codes and ordi-nances. Warranty is voided if wiring is not in accordance withspecifications. An open fuse indicates a short, ground, oroverload. Before replacing a fuse or restarting a compressoror fan motor, the trouble must be found and corrected.

Copper wire is required for all power lead terminations atthe unit while either aluminum or copper can be used for allother wiring.

Internal power wiring to the compressors for thesingle point versus the multiple point option are differ-ent. It is imperative that the proper field wiring beinstalled according to the way the unit is built.

ALR units may be ordered with internal power wiring foreither single or multiple point power connection. If singlepoint power connection is ordered, a single large powerterminal block is provided and wiring within the unit is sizedin accordance with the National Electrical Code. A single fieldsupplied disconnect is required. An optional factory mountedtransformer may be performed.

Canadian c-ETL listing

If multiple point power wiring is ordered, three powerconnections, one per compressor circuit plus one for con-denser fans and control circuit, are required and wiring withinthe unit is sized in accordance with the National ElectricalCode. Separate field supplied disconnects are required foreach of the three circuits. A single power block is provided forall of the condenser fans and the optional 115V controltransformer.

Canadian units which are c-ETL listed and are equipped formultiple point power connections have a sticker (see figurebelow) next to the wiring diagram in the control box. Thisnotifies the installer that local authorities may require the unitto be connected to a single electrical power source. Checkwith local authorities for requirements.

It may be desirable to have the unit cooler heater on aseparate disconnect switch from the main unit power supplyso that the unit may be shut down without defeating thefreeze protection provided by the cooler heater.

Table 14. Electrical data single point

03fiD

CWD

MOD

OS00

07QQ

085R

Although this umt maybe prowded withoptlons requiring morethan one source ofelectrical supply. someelectrical inspectlonauthorities may requirethis unit to beconnected to a wngleexternal electricalsupply.

continued on next page

IM 268 / Page 17

Sequence of OperationThe following sequence of operation is typical for ALRSeason Pak air cooled water chiIler. Models ALR035D throughALR 185D (items in italics apply only to Models ALR 0850through 185D). The sequence vanes somewhat dependingupon options.

Start-upWith the control circuit power on and the control stop switchS1 closed, 115V power is applied through the control circuitfuse F1 to the compressor crankcase heaters (HTR1 andHTR2 (HTR3 and HTR4), the compressor motor protectionsMP1 and MP2 (MP3 and M P 4 and the primary of the 24Vcontrol circuit transformer. The 24V transformer providespower to the contacts of the low pressure controls LP1 andLP2 and the compressor lockout time delays TD1 and TD2.

When the remote time clock or manual shutdown switchturns on the chilled water pump, the flow switch closes and115V power is applied to the relay contacts on the leavingwater control LWC1 The unit will automatically operate inresponse to the LWC1 provided the manual pumpdownswitches PS1 and PS2 are closed (in the “auto” position); thecompressor lockout time relays R5 and R6 (R7 and R8); andthefreezestats FS1 and FS2, high pressurecontrols HP1 andHP2, and the compressor motor protectors MP1 and MP2(MP3 and MP4) do not sense failure conditions.

On a call for cooling, the leaving water control LCW1energizes the liquid line solenoid valve SV1 for refrigerantcircuit #1, opening the valve and allowing refrigerant to flowthrough the expansion valve and into the evaporator. As theevaporator refrigerant pressure increases, the low pressure

control PL1 closes. This energizes the compressor startingrelay R9, starting the compressor via the compressor con-tactors Ml and M5. Closing the R9 contacts also energizesthecondenserfan motorcontacts M11, M12, Ml3 and M14,starting the fan motors.

As additional stages of cooling capacity are required, theleaving water control LCW1 energizes the liquid line solenoidvalve SV2 of the refrigerant circuit #2. After the compressorsequencing time delay TD11 has closed, the same startingsequence is initiated in refrigerant circuit #2.

If still more cooling is required, the leaving water controlwill start the remaining compressors and then de-energizeunloader solenoids until the capacity requirement is met.

PumpdownAs the leaving water control is satisfied, it will unload thecompressor(s) and then de-energize the liquid line solenoidvalve(s) SV1 and SV2, causing the valve(s) to close. When thecompressor has pumped most of the refrigerant out of theevaporator and into the condenser, the low pressure control(s)PL1 and LP2 will open. If the refrigerant leaks into the lowside causing the pressure to close the low pressure controlsLP1 and LP2, the compressor will start after a two-hour timedelay to pump the refrigerant into the condenser coil. If thereis a call for cooling during the two-hour time delay, the timeris bypassed and the compressor will start.

Note: Do not shut the unit down without going through thepumpdown cycle. Flow switch, time clock and ambientlockout thermostat must be wired to allow pumpdown whenunit is turned off.

IM 268 / Page 31

Start-up and Shutdown

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Pre Start-up8.With all electric disconnects open, check all screw or lug

type electric connections to be sure they are tight forgood electrical contact. Check all compressor valveconnections for tightness to avoid refrigerant loss atstart-up. Although all factory connections are tight be-fore shipment, some loosening may have resulted fromshipping vibration.

See that all auxiliary control equipment is operatrve andthat an adequate cooling load is available for initial start-up.

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Inspect all water piping for flow direction and correctconnections at the evaporator.

Check to see that the thermostat water temperaturesensor is installed in the leaving water line (supply tobuilding). On all ALR units the sensor well and sensor arefactory mounted.

Open the compressor suction and discharge shutoffvalves until backseated. Always replace valve seal caps.

Making sure control stop switch S1 is open (off) andpumpdown switches PS1 and PS2 are on “manualpumpdown,” throw the main power and control discon-nect switches to “on.” This will energize crankcaseheaters. Wait a minimum of 12 hours before starting upunit.

11.

Check the compressor oil level. Prior to start-up, the oillevel should cover at least one-third of the oil sightglass.

Check the voltage of the unit power supply and see thatit is within the *lo% tolerance that is allowed. Phasevoltage unbalance must be within *2%.

Check the unit power supply wiring for adequate am-pacity and a minimum insulation temperature of 75°C.

Open all water flow valves and start the chilled waterpump. Check all piping for leaks and vent theairfrom theevaporator as well as from the system piping. Flush theevaporator and system piping to obtain clean, noncor-rosive water in the evaporator.

Verifythat all mechanical and electrical inspections havebeen completed per local codes.

Most relays andterminals in the unit control center arehot with Sl and the control circuit disconnect on. Donot close S1 until start-up.

Start-upDouble check that the compressor suction and dis-charge shutoff valves are backseated. Always replacevalve seal caps.

Open the oil equalization line valve (ALR 085D through185D only).

Open the manual liquid line shutoff valve at the outlet ofthe subcooler.

Adjust the dial on temperature controller LCW1 to thedesired chilled water temperature and set the controlband (see “Thermostat” on page 37).

Start the auxiliary equipment for the installation byturning on the time clock, ambient thermostat and/orremote on/off switch, and chilled water pump.

Check to see that pumpdown switches PS1 and PS2 arein the “manual pumpdown” (open) position. If pressureson the low side of the system are above 60 psig (414kPa), the unit will start and pump down.

Temporary ShutdownMove pumpdown switches PSI and PS2 to the “manual It is important that the compressors pumpd down beforepumpdown” position. After the compressors have pumped the water flow to the unit is interrupted to avoid freeze-up indown, turn off the chilled water pump. the evaporator.

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After the compressor lockout timer TD1 has timed out,start the system by moving the pumpdown switchesPS1 and PS2 to the “auto pumpdown” position.

After running the unit for a short time, check the oil levelin each compressor crankcase, rotation of condenserfans, and check for flashing in the refrigerant sightglass(see “Maintenance” on page 34).

Superheat is factory adjusted to maintain between 8°Fand 12°F (4.4”C and 6.7”C). Verify that the superheat isbetween 8°F and 12°F (4.4X and 6.7X).

After system performance has stabilized, it is necessarythat the “Compressorized Equipment Warranty Form”(Form No. 415415Y) be completed to obtain full war-ranty benefits. This form is shipped with the unit, andafter completion should be returned to McQuay Servicethrough your sales representative.

Start-up After Temporary Shutdown1. Start the chilled water pump.

2. With emergency stop switch S1 in the “on” position, movepumpdown switches PS1 and PS2 to the “auto pump-down” position.

3. Observe the unit operation for a short time to be sure thatthe compressors do not cut out on low oil pressure.

If shutdown occurs or will continue through periodsbelow freezing ambient temperatures, make provi-sions to insure against chiller vessel freeze-up.

Page 32 / IM 268

Extended Shutdown1. Close the manual liquid line shutoff valves.

2. After the compressors have pumped down, turn off thechilled water pump.

3. Turn off all power to the unit and to the chilled water pump.

6. Tag all opened disconnect switches to warn against start-up before the compressor suction and discharge valves.

7. If glycol is not used in the system, drain all water from theunit evaporator and chilled water piping if the unit is to beshut down during winter. Do not leave the vessels or

4. Move the emergency stop switch S1 to the “off” position.

5. Close the compressor suction and discharge valves andthe oil equalization line valve.

piping open to the atmosphere over the shutdownperiod.

System MaintenanceGeneral

On initial start-up and periodically during operation, it will benecessary to perform certain routine service checks. Amongthese are checking the compressor oil level and takingcondensing, suction and oil pressure readings. During theoperation, the oil level should be visible in the oil sightglasswith the compressor running. On units ordered with gauges,condensing, suction and oil pressures can be read from thevertical supports on each side of the unit adjacent to thecompressors.

The gauges are factory installed with a manual shutoffvalve on each gauge line. The valves should be closed at alltimes except when gauge readings are being taken. On unitsordered without gauges, Shrader fittings should be installedin the plugged ports provided on the suction and dischargeKing valves on each compressor circuit,

Fan Motor BearingsThe fan shaft bearings are of the permanently lubricated type. No lubrication is required.Excessive fan motor bearing noise is an indication of a potential bearing failure.

Electrical TerminalsAll power electrical terminals should be retightened every sixmonths, as they tend to loosen in service due to normalheating and cooling of the wire.

Electric shock hazard. Turn off all power before con-tinuing with following service.

Compressor Oil LevelThe oil level should be watched carefully upon initial start-upand for some time thereafter.

At the present time, Suniso No. 3GS, Calumet R015, andTexaco WF32 oils are approved by Copeland for use in thesecompressors. The oil level should be maintained at aboutone-third of the sightglass on the compressor body. Oillevels may fluctuate between compressors in the samerefrigerant circuit on four-compressor units (ALR 085Dthrough185D).

Oil may be added to the Copeland compressor throughthe oil fill hole in the crankcase. To add oil, isolate the crank-case and pour or pump in the necessary oil. If the systemcontains no refrigerant, no special precautions are neces-

sary other than keeping the oil clean and dry.If the system contains a refrigerant charge, close the

suction valve and reduce crankcase pressure to 1 to 2 psig(6.9 to 13.8 kPa). Stop the compressor and close the dis-charge valve.

Add the required amount of oil. During the period thecompressor is exposed to the atmosphere, the refrigerantwill generate a vapor pressure, retarding the entrance ofcontaminants. Before resealing the compressor, purge thecrankcase by opening the suction valve slightly for 1 or 2seconds. Close the oil port, open the compressor valves andrestore the system to operation.

Oil EqualizationUnits with four compressors (ALR 085D through 185D) comeequipped with oil equalization lines connecting the crank-cases of both compressors in each refrigerant circuit. Thisallows the oil to move from one compressor crankcase to theother during normal operation, and balance between the twowhen the compressors are off. This method of equalizationprohibits the oil level from dropping below the level of thesightglass. Some difference in crankcase oil levels wills till

exist during unit operation.The oil equalization line contains a manual shutoff valve

for isolating a compressor during service work. The ballvalves are shipped in the closed position with a tag attachedstating “Notice, Valve Shipped In Closed Position. Can BeOpen For Normal Operation.” When valves are closed forcompressor service, make sure they are opened again forunit operation.

IM 268 / Page 33

CondensersCondensers are air cooled and constructed with 7~” (9.5mm) supply outlets. Use caution when applying such cleaners asO.D. internally finned copper tubes bonded in a staggered they may contain potentially harmful chemicals. Care shouldpattern into slit aluminum fins. No maintenance is ordinarily be taken not to damage the fins during cleaning. Periodic userequired except the occasional removal of dirt and debris of the purge valve on the condenser will prevent the buildupfrom the outside surface of the fins. McQuay recommends of nonconcondensables. The purge valve is located underthe use of foaming coil cleaners available at air conditioning the #1 fan deck of each compressor circuit.

Refrigerant SightglassThe refrigerant sightglasses should be observed periodi-cally. (A monthly observation should be adequate.) A clearglass of liquid indicates that there is adequate refrigerantcharge in the system to insure proper feed through theexpansion valve. Bubbling refrigerant in the sightglass indi-cates that the system is short of refrigerant charge. Refriger-ant gas flashing in the sightglass could also indicate an

excessive pressure drop in the line, possibly due to a cloggedfilter-drier or a restriction elsewhere in the system. An ele-ment insidethe sightglass indicates what moisture conditioncorresponds to a given element color. If the sightglass doesnot indicate a dry condition after about 12 hours of operation,the unit should be pumped down and the filter-driers changed.

Lead-LagAn optional feature on all McQuay ALR air cooled chillers isa system for reversing the sequence in which the compres-sors start. (Chillers with the hot gas bypass option on onlyone circuit do not have lead-lag.) For example, on a unit withthe lead-lag switches in the “circuit 1 leads” position, thenormal starting sequence is compressor #1 then compres-

sor #2. With the lead-lag switches in the “circuit 2 leads”position, the reversed starting sequence is compressor #2,then compressor #1 . It is achieved electrically by a multipoleswitching arrangement. It is suggested that the lead-lagswitches in the unit control center be switched annually toprovide even compressor life.

Service

Service on this equipment is to be performed byI I

Disconnect all power before doing any service insidequalified refrigeration personnel familiar with equip- the unit.ment operation, maintenance, correct servicing pro- I 1cedures, and the safety hazards inherent to this work.Causes for repeated tripping of safety controls mustbe investigated and corrected.

requirements set forth by the EPA in regards to refrig-

Filter-DriersTo change the filter-drier, pump the unit down by movingpumpdown switches PS1 and PS2 to the“manual pumpdown”position.

controls. Close the manual liquid line shutoff valve(s). Turnpower to the unit back on and restart the unit by moving thecontrol switch S1 to the “on” position. The unit will startpumping down past the low pressure setting. When theevaporator pressures reaches 0 to 5 psig (0 to 34.5 kPa),move control switch S1 to the “off” position.

Frontseat the suction line King valve(s). Remove andreplace the filter-drier(s). Evacuate the lines through theliauid line manual shutoff valve(s) to remove noncondensablesthat may have entered during filter replacement. Aleakcheckis recommended before returning the unit to operation.

Move the control switch S1 to the “off” position. Turn offall power to the unit and install jumpers across the terminalsshown in the table. This will jump out the low pressure

Liquid Line Solenoid ValveThe liquid line solenoid valves, which are responsible forautomatic pumpdown during normal unit operation, do notnormally require any maintenance. They may, however,require replacement of the solenoid coil or of the entire valveassembly.

The solenoid coil may be removed from the valve bodywithout opening the refrigerant piping by moving pumpdownswitches Ps1 and PS2 to the “manual pumpdown” position.

The coil can then be removed from the valve body by simplyremoving a nut or snap-ring located at the top of the coil. Thecoil can then be slipped off its mounting stud for replace-ment Be sure to replace the coil on its mounting stud beforereturning pumpdown switches Ps1 and PS2 to the “autopumpdown” position.

To replace the entire solenoid valve, follow the stepsinvolved when changing a filter-drier.

Page 34 / IM 268

Thermostatic Expansion ValveThe expansion valve is responsible for allowing the properamount of refrigerant to enter the evaporator regardless ofcooling load. It does this by maintaining a constant super-heat. (Superheat is the difference between refrigerant tem-perature as it leaves the evaporator and the saturationtemperature corresponding to the evaporator pressure.) AllALR chillers are factory set for between 8°F and 12°F (4.4%to 6.7%) superheat. If it is necessary to increase the super-heat setting of the valve, remove the cap at the bottom of thevalve to expose the adjustment screw. Turn the screwclockwise (when viewed from the adjustment screw end) toincrease superheat and counterclockwise to reduce super-heat. Allow time for system rebalance after each superheatadjustment.

Figure 19. Thermostatic expansion valve

The expansion valve, like the solenoid valve, should notnormally require replacement, but if it does, the unit must bepumped down by following the steps involved when chang-ing a filter-drier.

If the problem can be traced to the power element only, itcan be unscrewed from the valve body without removing thevalve, but only after pumping the unit down.

Power Element(Contains Diaphragm)

- Spring

Adjustment Screw

EvaporatorThe evaporator is of the direct expansion, shell-and-tubetype with refrigerant flowing through the tubes and waterflowing through the shell overthetubes. The tubes are inter-nally finned to provide extended surface as well as turbulentflow of refrigerant through the tubes. Normally no servicework is required on the evaporator. There may be instanceswhere a tube will leak refrigerant into the water side of thesystem. In the cases where only one or two tubes leak, theproblem can best be solved by plugging the tube at bothends. When the tube must be replaced, the old tube can beremoved and replaced.

To remove a tube, the unit should be temporarily pumpeddown. Follow the steps involved when changing a filter-drier.The tubes are mechanically expanded into the tube sheets(see Figure 20) at each end of the cooler. In order to removethe tubes, it is necessary to break this bond by collapsing thetube. After doing this at both ends of the shell, the tube canbe removed for replacement. The new tube can then beinserted and re-expanded into the tube sheet.

The bond produced by expansion must be refrigeranttight. This bond must be produced by applying Locktite(red) to the tube and rolling it into the tube sheet.

After re-assembling the evaporator, a small amount ofrefrigerant should be introduced by momentarily opening themanual liquid line valve. A leak check should then be per-formed on the evaporator.

Tube removal can only take place after the leaking tube islocated. One method would be to subject each tube to airpressure by plugging each end and, with a pressure gaugeattached to one of the end plugs, observing if there is a lossof air pressure over a period of a minute or two.

Another method is to place a cork plug in each tube onboth ends of the cooler and applying pressure to the shell ofthe cooler. After a period of time, the pressure will leak fromthe shell into the leaking tube or tubes and pop out the corkplug.

view of typical dual circuit shell-and-tube evaporator

Liquid Connections

Re rlgerant lubes

Water Nozzles

IM 268 / Page 35

In-Warranty Return Material Procedure

CompressorCopeland Refrigeration Corporation has stocking wholesal-ers who maintain a stock of replacement compressors andservice parts to serve refrigeration contractors and servicepersonnel.

When a compressor fails in warranty, contact your localsales representative, or Warranty Claims Department at theaddress on the cover of this bulletin. You will be authorizedto exchange the defective compressor at a Copeland whole-saler, or an advance replacement can be obtained. A creditis issued you by the wholesaler for the returned compressorafter Copeland factory inspection of the inoperative com-pressor. If that compressor is out of Copeland’s warranty asalvage credit only is allowed. Provide full details; i.e, unit

model and unit serial numbers. Include the invoice and thesalvage value credit memo copies and we will reimburse thedifference. In thistransaction, be certain that the compressoris definitely defective. If a compressor is received from thefield that tests satisfactorily, a service charge plus a trans-portation charge will be charged against its original creditvalue.

On all out-of-warranty compressor failures, Copelandoffers the same field facilities for service and/or replacementas described above. The credit issued by Copeland on thereturned compressor will be determined by the repair chargeestablished for the particular unit.

Components Other Than CompressorsMaterial may not be returned except by permission of autho-rized factory service personnel at Minneapolis, Minnesota. A“return goods” tag will be sent to be included with thereturned material. Enter the information as called for on thetag in order to expedite handling at our factories and promptissuance of credits.

The return of the part does not constitute an order forreplacement. Therefore, a purchase order must be enteredthrough your nearest McQuay representative. The order

should include part name, part number, model number andserial number of the unit involved.

Following our personal inspection of the returned part,and if it is determined that the failure is due to faulty materialor workmanship, and in warranty, credit will be issued oncustomer’s purchase order.

All parts shall be returned to the pre-designated factory,transportation charges prepaid.

Page 36 / IM 268

AppendixStandard Controls

Perform an operation check on all unit safety controlsonce per year.

ThermostatThe AS-UNT33n-1 microprocessor-based leaving watercontrol is designed to control multiple capacity steps ofcooling from a single sensor.

The device is provided with up to eight steps of capacity.The AS-UNT33n-1 operation is based on an adjustablesetpoint and control band as shown in “Control Band” below.If the Leaving Chilled Water Temperature begins to rise to thedesired setpoint plus control band /2 (upper limit), coolingstage 1 makes bringing on the first stage of cooling. Addi-tional stages of cooling will follow as long as the leaving watertemperature remains above the upper limit of the controlband. As the leaving water temperature begins to drop tosetpoint minus control band /2 (lower limit), cooling stageswill begin to de-energize.

There will be no energizing or de-energizing of coolingstages as long as the leaving water temperature is betweenthe upper and lower limits of the control band.

As a rule, any time the leaving water temperature is abovethe upper limit of the control band, stages will be energized,and anytime the leaving water temperature falls below thelower limit of the control band, stages will be de-energized.

At the initial start of the unit a time delay will occur. Thereis a 60 second interstage On Delay between stages. Eachstage incorporates minimum on and off timers with a maxi-mum cycle rate of six cycles per hour.

Note: Refer to bulletin IM 552 for a more complete de-scription of the control’s application, settings, adjustments,and checkout procedures.

Control bandLeaving Water Temperature will be controlled to the ActualLeaving Water Setpoint. The Actual Leaving Water Setpointwill be a function of what mode of operation the controller isin and if a reset option is used. The Control Band potentiom-eter located on the front of the controller is used to determinethe Actual Leaving Dead Band and Prop Band.

Actual Leaving Dead Band: Control band (A16)/2.Actual Leaving Prop Band: Dead band * number of stages.

Example:Control band = 4°F (2.2%)Number of stages = 6Dead band = 4/2 =2”F (1 .1 “C)Prop band = 2*6 = 12°F (6.7%)

As the Leaving Water Temperature rises above the ActualLeaving Water Setpoint, but within the Leaving Dead Band,there will be no Compressor Command (Staging). As theLeaving Water Temperature continues to rise above theDead Band and into the Prop Band, the Compressor Com-mand will be increased. When Leaving Integration Gain isused, a Proportional Plus Integral command will be calcu-lated. As the Compressor Command increases, stages ofcooling capacitywill be energized. Minimum on, off, interstagetimers, and cycles per hour attributes will control the stages.

As the Leaving Water Temperature decreases towards

Figure 27. AS-UNT33n-1 leaving water control algorithmoperation

the Actual Leaving Water Setpoint, the Compressor Com-mand will be decreased. Upon re-entering the Dead Band,the current Compressor Command will be maintained. If theLeaving Water Temperature falls below the Actual LeavingWater Setpoint (using the same Dead Band), the CompressorCommand will again start to decrease.

The “Control Band” is the non-stage area of the controller.Anytime the Leaving Water Temperature is outside of theControl Band limits, staging will occur. Anytime the LeavingWater Temperature is within the Control Band limits, nostaging occurs. As shown in the figure below, with a 45°F(7.2%) setpoint and a 4°F (2.2%) Control Band setting,stages of cooling energize when the Leaving Water is 47°F(8.3%) or higher. Stages de-energize when the LeavingWater is 43°F (6.1%) or lower [4”F (2.2%) difference]. Allstages wi l l remain in their current state between 43°F (6.1 “C)and 47°F (8.3%).

Operation limitsDo not operate unit at a thermostat setting below 42°F (6°C)or above 50°F (10%) as serious problems may result such ascooler freeze-up or compressor overheating.

Oil pressure safety controlThe oil pressure safety control is a manually resettabledevice which senses the differential between oil pressure atthe discharge of the compressor oil pump and suctionpressure inside the compressor crankcase. When the oilpressure reaches approximately 15 psig (103 kPa) above thecrankcase suction pressure, the pressure actuated contactof the control opens from its normally closed position. If thispressure differential cannot be developed, the contact willremain closed and energize a heater element within thecontrol. The heater element warms a normally closed bime-tallic contact and causes the contact to open, de-energizinga safety relay and breaking power to the compressor.

It takes about 120 seconds to warm the heater elementenough to open the bimetallic contact, thus allowing time forthe pressure differential to develop.

If during operation, the differential drops below 10 psig

IM 268 / Page 37

(69 kPa), the heater element will be energized and thecompressor will stop. The control can be reset by pushingthe reset button on the control. If the compressor does notrestart, all a few minutes for the heater elements and bime-tallic contacts to cool and reset the control again.

To check the control, pumpdown and shut off all power tothe unit. Open thecircuit breakers or the fused disconnect forthat compressor and install a voltmeter between terminals Land M of the oil pressure control. Turn on power to the unitcontrol circuit (separate disconnect or main unit disconnectdepending on the type of installation). Check to see that thecontrol stop switch S1 is the “on” position. The control circuitshould not be energized, but with the absence of compressorpower, no oil pressure differential can develop and thus thepressure actuated contacts of the control will energize theheater element and open the bimetallic contacts of thecontrol within 120 seconds. When this happens, the safetyrelay is de-energized, the voltmeter reading will rise to 115V,and the compressor contactor should open. Repeated op-erations of the control will cause a slight heat buildup in thebimetallic contacts resulting in a slightly longer time for resetwith each successive operation.

Figure 22. Oil pressure safety control

Pressure Actuatorcontact

Heater Element

IT2

L MLine Neutral

Note 2

Bimetallic Contacts Safety Relay

Notes: 1. Hot only when unit thermostat calls for compressor to run.2. Hot only when other safety control contacts are closed.

High pressure controlThe high pressure control is a single pole pressure activatedswitch that closes on a pressure rise. When the switchcloses, R1 is energized which in turn de-energizes thecontrol circuit, shutting down thecompressor circuit. R1 alsolocks itself in a manually resettable holding circuit throughRS1 . The switch is factory set to close at 400 psig (2759 kPa)and open at 300 psig (2069 kPa).

To check the control, either block off condenser surfaceor start the unit with condenser fan motor fuses in only onefan fuse block (FB6) and observe the cutout point of thecontrol on a high pressure gauge

The control is attached to a Shrader fitting and is locatedon a cylinder head near the discharge King valve.

Aftertesting the high pressure control, check the pressurerelief device (on the condenser header) for leaks.

Although there is an additional pressure relief devicein the system set at 450 psig (3104 kPa), it is highlyrecommended that the “control stop” switch S1 beclose at hand in case the high pressure control shouldmalfunction.

Low pressure controlThe low pressure control is a single pole pressure switch thatcloses on a pressure rise. It senses evaporator pressure andis factory set to close at 60 psig (414 kPa) and automaticallyopen at 35 psig (241 kPa). To check the control (unit must berunning), move the pumpdown switch(es) PSI and PS2 to the“manual pumpdown” position. As the compressor pumpsdown, the evaporator pressure will drop. The lowest evapo-

rator pressure reached before cutout is the cutout setting ofthe control. Wait for the compressor lockout time delay(s)TD1 and TD2 to timeout. By moving the pumpdown switch(es)PS1 and PS2 to the “auto pumpdown” position, evaporatorpressure will rise. The highest evaporator pressure reachedbefore compressor restart is the cutin setting of the control.

The control is attached to a Shrader fitting and is locatedbelow the suction King valve body.

Compressor lockoutCompressor lockout consists of a fixed 5-minute time delay.It is wired in series with the R5 relay starting the compressor.Its purpose is to prevent rapid compressor cycling whencooling demands are erratic. The circuit illustrated in Figure23 is for the compressor circuit #1 control circuit. The controlcircuit for compressor circuit #2 is wired the same way. Whenthe unit thermostat no longer calls for cooling and thecompressor contactor have opened, the lockout timedelay breaks open the circuit, preventing compressor re-start.

The circuit remains open for a period of five minutes sothat, if the unit thermostat should call for cooling before thedelay period has expired, the compressor will not restart.After five minutes the time delay will close its contacts tocomplete the circuit to R5, energizing R9 and starting thecompressor. When R9 is energized, another set of contactswill shunt around TD1 to reset open for timing out the nextcompressor cycle.

To check the control, the compressor must be runninginitially. Move the pumpdown switch PS1 or PS2 to the“manual pumpdown” position. The compressor should notrestartforfive minutes. Each refrigerant circuit can becheckedthe same way.

Figure 23. Compressor lockout

L1lleFEI II I

Neutral

LineeN e u t r a li “i”l F i @

I39Line I I Ml

_ Neutral

1 o T

Compressor motor protectorThe solid-state compressor motor protector module incor-porates atwo-minute “time off” relay utilizing the bleed downcapacitor principle. Any time the protection system opens orpower to the module is interrupted, the two-minute “time off”delay is triggered, and the module will not reset for twominutes. Once the two-minute period is passed, the motorprotector contacts 1 and 2 reset, provided the protectionsystem is satisfied and power is applied to the module.

Note: If the power circuit is broken once the two-minuteperiod is passed, the pilot circuit will reset without delaywhen power is reapplied.

Figure 24. Compressor motor protector

24V LineControl

-----‘Irl 2

RelayI Neutral

1 1 SV Line

‘age 38 / IM 268

Fan Trol head pressure controlFanTrol is a method of head pressurecontrol which automati-cally cycles the condenser fans in response to condenserpressure and ambient air temperature. This maintains headpressureand allows the unit to run at low ambient air temper-atures.

All ALR units have dual independent circuits with the fansfor circuit 1 and circuit 2 being controlled independently by

Table 19. Factory FanTrol settings

the condensing pressure and ambient air of each circuit.Fans 11 and 21 start with each compressor and fans 12 and22 cycle on and off in response to condenser pressure. Thecutout and cutin pressures are given in Table 19. Fans 13 and14 (circuit 1) and fans 23 and 24 (circuit 2) are controlled byambient temperature and are factory set at the values givenin the table. Note that the number of fans on each unit varies.FanTrol sensor locations are shown in Figures 25 through 28.

Notes:0 With SpeedTrol all unit minimum ambient operating temperature drops to 0°F (18°C)0 Minimum head pressure on partly loaded compressor is 110 psig (759 kPa); on full load it is 170 psig (1172 kPa).

SpeedTrol and FanTrol will provide reasonable operating refrigerant discharge pressures to the ambient temperatures listedfor them provided the coil is not affected by the existence of wind. If wind may occur, and the unit includes verticalcondenser coils, it is the responsibility of the system designer or installer to make other provisions for low ambient control.Consideration should be given to deflecting awnings, dampers, or a floodback receiver system as required to satisfy specificjob conditions.

IM 268 / Page 39

Optional Controls

SpeedTrol head pressure control(optional)The SpeedTrol system of head pressure control operates inconjunction with FanTrol by modulating the motor speed onfans 11 and 21 in response to condensing temperature. Byreducing the speed of the last fan as the condensing pres-sure falls, the unit can operate at lower ambient tempera-tures.

The SpeedTrol fan motor is a single phase, 208/240 volt,thermally protected motor specially designed for variablespeed application. The solid-state speed controls SC1 1 andSC21 are mounted inside condenser fan 11 and 31 fancompartment. Units with 460 volt power have a transformermounted inside the condenser fan 21 fan compartment tostep the voltage down to 230 volts for the SpeedTrol motor,shown in Figures 26 and 28.

The SpeedTrol control starts to modulatethe motor speedat approximately 230 psig (1586 kPa) and maintains a mini-

Figure 25.

High Ambient%?llSCVS

PC6 a PCS

Figure 27.FanTrol SensorsPC22 a PC12

mum condensing pressure of 170 to 180 psig (1172 to 1241kPa).

The SpeedTroI sensors are clipped to a return bend on thebottom row of the condenser coil.

High ambient control (optional)The high ambient control is a single pole, pressure activatedswitch that closes on a pressure rise to partially unload oneor both circuits. It senses condenser pressure and is factoryset to close at 375 psig (2586 kPa) and will automaticallyreset at 300 psig (2069 kPa). To check the control eitherblock off condenser surface or start the unit with condenserfan motor fuses in only fan fuse block (FB6) and observe thecutin point of the control by monitoring when the compressorunloads. The purpose of the control is to allow the unit tocontinue operating when the ambient temperature exceedsthe design temperatures of unit. High ambient sensor loca-tions are shown in Figures 25 and 27.

Figure 26.

SpeedTw Controls

Figure 28.

SpeedTrol Controls

FanTrol Sens orsTC13. TC14. TC23, TC24

Page 40 I IM 268

High return water control (optional) Freeze control (optional)The high return water control senses the temperature ofreturn water and partially unloads one or both compressorcircuits. The control has an adjustable 0 to 100°F (17.8 to37.8%) temperature range with 3°F (1.7%) switch differen-tial.

The purpose of the control is to prevent high superheatedsuction temperatures entering the compressor should thereturn water temperature become too high. High suctiontemperature with the compressor at full load could result inserious damage to the compressor. A 70°F (21 .l”C) setpointis recommended for the high return water thermostat.

The freeze control is a single pole pressure switch that closeson a pressure fall. It contains a pressure actuated contactthat, upon a fall in evaporator pressure, energizes a 60-second time delay. Aftertiming out, R1 is energized which inturn de-energizes the 24V control circuit, shutting down thecompressor circuit. R1 also locks itself into a manually reset-table holding circuit through RS1 The control is factory setto close at 54 psig (372 kPa) and open at 57 psig (393 kPa).The 60-second time delay prevents nuisance cutouts due tomomentary drops in suction pressure.

The unit is shipped from the factory with the controlsensor taped to the bottom of the control box and must befield installed. It is recommended that the sensor be clampedto the side of the return water line near the cooler connectionand insulated (see Figure 6).

To check the control, the system should be operating atfull load conditions. By slowly turning the dial setting down,the control should partially unload one compressor circuit.By continuing to dial the setting down, the second compres-sor circuit should unload depending on what the interstagedifferential is set at.

To check the setpoint of the freezestat, attach one lead ofthe voltmeter to terminal 46 in the control box and the otherlead to ground to check circuit #1. With the unit running anda suction pressure above 57 (393 kPa), there should be 0 VACto ground. To check the cutin point of the freezestat, slowlyclose off the manual liquid line shutoff valve bringing thesuction pressure down. When the freezestat switch closes,slowly close off the manual liquid line shutoff valve bringingthe suction pressure down. When the freezestat switchcloses, the voltmeter will read 24V to ground. The corre-sponding pressure will be the cutin point of the control.Slowly open the manual liquid line valve to check the cutoutpoint pressure of the control. To check the calibration of thefreezestat for compressor circuit #2, attach the voltmeterbetween terminal 76 and ground and repeat the same steps.

Low ambient start (optional)Low ambient start is available on all units as an option withFanTrol and included automatically with optional SpeedTrol.It consists of a solid-state, normally closed time delay wiredin series with a relay. These are both wired in parallel to theliquid line solenoid valve so that when the solenoid valve isenergized by the unit thermostat the low ambient start relayis also energized through the time delay. The relay has con-tacts that essentially short circuit the low pressure controland freezestat and allow the compressorto start with the lowpressure control open.

After about 2-3/4 minutes, the time delay will open and de-energize the relay. If the system has not built up enoughevaporator pressure to close the low pressure control, thecompressor will stop. The time delay can be reset to itsoriginal normally closed position by moving the pumpdownswitch(es) PSI or PS2 to the “manual pumpdown” position.Moving the pumpdown switch back to the “auto pumpdown”position will again energize the relay for another attempt atstart-up. If the system has built up enough evaporatorpressure, the compressor will continue to run.

To check the control, turn off all power to the unit andremove the wire(s) leading to the terminals of the low pres-sure control(s) LP1 and LP2 and the freezestat FS1 andFS2. Remove power to the compressor and jumper acrossterminals 48 to 50 for circuit 1 and 78 to 80 for circuit 2.Switch the pumpdown switch(es) PS1 and PS2 to the “autopumpdown” position. Energize the control circuit by turningon the control circuit disconnect or main power disconnect(depending on the installation) and the control stop switchS1 The compressor contactors should pull in instantly andtrip back out after the 2%minute time delay.

Figure 29. Low ambient start

Low AmbientLow Ambient

Start Time Delaystart Relay

Line TD9 Neutral

T

Note: Line is only hot when the unit thermostat calls for compressor to run.

To adjust the control if necessary, remove the setpointlocking bracket from the top of the control. Unscrew thepressure connection off the Shrader fitting on the suctionline. Attach the pressure connection to a refrigerant tankthrough a set of compound gauges and slowly pressurize theswitch while listening for the cutin and cutout points ofcontrol.

Turn theadjusting stem clockwise in%-turn increments todecrease the cutin pressure of the control and counterclock-wise to increase the cutin pressure of the control. After thecontrol is calibrated, reconnect the pressure connection tothe Shraderfitting on the suction line and reattach the lockingbracket to the top of the control.

Part winding start (optional)Part winding start is available on all voltage units and con-sists of a solid-state time delay wired in series with thecontactor that energizes the second winding of each com-pressor motor. Its purpose is to limit current inrush to thecompressors upon start-up. As each compressor starts, thecontactor of the first motor winding is delayed for 1 second.

Control checkout is best accomplished by observation aseach contactor is pulled in to see that the 1 second delayoccurs before the second contactor pulls in.

Figure 30. Part winding start

Compr. Contactor#1 Motor Winding)

Line

ITD1

APart WindingTime Delay

Compr. Contactor(#2 Motor Windlng)

Phase/voltage monitor (optional)The phase/voltage monitor is a device which provides pro-tection against three-phase electrical motor loss due topower failure conditions, phase loss, and phase reversal.Whenever any of these conditions occur, an output relay isdeactivated, disconnecting power to the thermostatic con-

IM 268 / Page 41

trol circuit, automatically pumping down the unit.The output relay remains deactivated until power line

conditions return to an acceptable level. Trip and resetdelays have been provided to prevent nuisance tripping dueto rapid power fluctuations.

When three-phase power has been applied, the outputrelay should close and the “run light” should come on. If theoutput does not close, perform the following tests:

Check the voltages between L1-L2, L1 -L3 and L2-L3.These voltages should be approximately equal and within+lO% of the rated three-phase line-to-line voltage.

If these voltages are extremely low or widely unbalancedcheck the power system to determine the cause of theproblem.

If the voltages are good, turn off the power and inter-change any two of the supply power leads at the discon-nect.

This may be necessary as the phase/voltage monitor issensitive to phase reversal. Turn on the power. The outputrelay should not close after the appropriate delay.

Hot gas bypass (optional)Hot gas bypass is a system for maintaining evaporator pres-sure at or above a minimum value. The purpose for doing thisis to keep the velocity of the refrigerant as it passes throughthe evaporator high enough for proper oil return to the com-pressor when cooling load conditions are light. It also main-tains continuous operation of the chiller at light load condi-tions.

The system consists of a solenoid valve piped in serieswith a pressure regulating valve as shown in Figure 31. Thesolenoid valve is factory wired to open whenever the unitthermostat calls for the first stage of cooling. The pressureregulating valve is factory set to begin opening at 58 psig(400 kPa) 132°F (0°C) for R-221 when the air charged bulb isin an 80°F (26°C) ambient temperature. Since the bulb isfactory mounted on the suction line, and suction line tem-peratures are usually in the 50°F to 60°F (10°C to 60°C)range, Figure 32 indicates that for ALR chillers, the valve isfactory set to begin opening at 54 to 56 psig (372 to 386 kPa).This setting can be changed by changing the pressure of theair charge in the adjustable bulb. To raise the pressuresetting, remove the cap on the bulb and turn the adjustmentscrew clockwise. To lower the setting, turn the screw coun-terclockwise. Do not force the adjustment beyond the rangeit is designed for, as this will damage the adjustment assem-bly.

The regulating valve opening point can be determined byslowly reducing the system load (or increasing the requiredchilled water temperature setting indicated on the unit ther-mostat) while observing the suction pressure. When the by-pass valve starts to open, the refrigerant line on the evapo-rator side of the valve will begin to feel warm to the touch.

The gas line may become hot enough to cause injuryin a very short time; care should be taken duringvalve checkout.

Figure 31. Hot gas bypass diagram

Solenoid Valve

stable Remote Bulb

External Equalizer ConnectionTo Suction Side of Evaporator

Bypas Valve

To Evaporator InletAfter Expansion Valve

Figure 32. Hot gas bypass adjustment range

Page 42 I IM 268

Controls, Settings and Functions

I FUNCTION 1 SYMBOL ] SETTING1 Protects the evaporator from water freeze-up. 1 FS1, 2 !! Closes at 54 psig (372 kPa)

Opens at 57 psig (393 kPa)Time delay prevents nuisance trips. TD15, 16 60 secondStops compressor when discharge pressure is too HP1, 2 Closes at 400 psig (2759 kPa)high. Opens at 300 psig (2069 kPa)(Used for pumpdown) Stops compressor when suction LPI, 2 Closes at 60 psig (414 kPa)pressure is too low. Opens at 35 psig (241 kPa)Protects motor from high temperature by sensing MP1-4 500 ohms cold to 20,000winding temperature. ohms hot

(Texas Instruments)Oil Pressure Control

High Ambient UnloaderPressure ControlFanTrol CondenserPressure Control

Stops compressor if oil pressure drops below setpolnt OP1-4 Pressure sensor opens at 15for 120 seconds. psig (103 kPa) oil pressure

drops below 10 psig (69 kPa)the sensor closes, energizing a120 second delay before stop-ping the compressor.

Unloads compressor circuits if condenser pressure is PC5. 6 Closes at 375 psig (2586 kPa)too high. Opens at 300 psig (2069 kPa)Maintains condenser pressure by cycling the con- PC1 2,22 See table with FanTrol settings.denser fans in response to ambient air temperature TC13,14,15(TC) and condenser pressure (PC). TC23, 24, 25

Pumpdown SwitchPhase/Voltage Monitor

Reset Switches

Control Stop SwitchLead-Lag Switches

Used to manually pump down compressor circuit.Protects motor from power failure, phase loss andphase reversal.Restarts compressor circuit if it cuts out on highpressure or freezestat.Shuts down entire control circuit.

Reverses sequence that compressors start in.

PSI. 2 Auto/manualP V M - N/A

RS1 -4 N/A

S1 On/offS2-4 - 1 Circuit1 leads Circuit 2 or

RESET’ LOCATIONManual thru RS1, 2 Suction line near cooler

DIFFERENTIAL3 psig (21 kPa), fixed.

N/A

Manual thru RS1, 2Control box

On compressorN/A

100 psig (690 kPa), fixed

Auto On compressor 30 psig (207 kPa), fixed

Auto from 2700-4500 ohms Compressor junction box 15,000 ohms

Manual

Auto

Auto

On condenser coil header 75 psig (517 kPa)

PC1 2-22 on coil header See table with FanTrolTC13-25 in control box settingsSensors mounted in backof control box

N/A Control box N/AWhen conditions return to Control box N/Aan acceptable level.Manual

N/A

N/A

N/A

Control box N/A

Control box N/AControl box N/A

Back of control box or on N/Abulkhead

N/A

N/A

Condenser section on liquid N/Aline after filter-drier and be-fore TEV.

Condenser section N/A

N/A

N/A

Control box. Sensor in Adjustable control bandsupply water line to building from 0°F to 10°F (-17.8”Cfrom chiller. (-12.2%)

Control box Adjustable thru LWC1

On cooler

Control box

N/A

3°F (1.7”C), fixed

I

Continued on next page

The McQuay ALR SeasonPak air cooled water chiller provides not only lower operating costs, butlower installation costs, low maintenance costs and greater design flexibility, in both comfort andprocess cooling applications.

In order for McQuay to better serve our customers, feedback of recurring service problems orcomplaints dealt with in the field would be appreciated. Problems or complaints can be reported toMcQuay by filling out a Product Quality Report (Form No. 2S-636-784). These forms are availablefrom McQuay Service and sales representative organizations and should be routed back throughthese organizations to McQuay’s Engineering and Marketing departments.

Troubleshooting Chart

Compressor will 1 1 . Main swi tch2. Fuse blown. Circuit breakers open.

3. Thermal overloads tripped.

4. Defective contactor or coil.5. System shut down by safety devices

6. No cooling required.7. Liquid line solenoid will not open.8. Motor electrical trouble.9. Loose wiring.

1. Flooding of refrigerant into crankcase.2. Improper piping support on suction or liquid line.3. Worn compressor.

1. Noncondensables in system.2. System overcharged with refrigerant.3. Discharge shutoff valve partially closed.4. FanTrol out of adjustment.5. Fan not running.6. Dirty condenser coil.

1. Faulty condenser temperature regulation.2. Suction shutoff valve partially closed.3. Insufficient refrigerant in system.4. Low suction pressure.5. Compressor operating unloaded.

1. Excessive load.2. Expansion valve overfeeding.3. Compressor unloaders open.

1. Lack of refrigerant.2. Evaporator dirty.3. Clogged liquid line filter-drier.4. Clogged suction line or compressor suction gas strainers.5. Expansion valve malfunctioning.6. Condensing temperature too low.7. Compressor will not unload.8. Insufficient water flow.9. Evaporator head ring gasket slippage.

3. Faulty thermostat stage or broken wire.

1. Clogged suction oil strainer.2. Excessive liquid in crankcase.

3. Oil pressure gauge defective.

4. Low oil pressure safety switch defective5. Worn oil pump.6. Oil pump reversing gear stuck in wrong position7. Worn bearings.8. Low oil level.

into crankcase.

2. Excessive compression ring blow-by3. Suction superheat too high.4. Crankcase heater burnout.

1. Close switch2 Checkelectricalcircurtsand motorwtndingforshortsorgrounds

Investigate for possible overloading. Replace fuse or resetbreakers after fault is corrected. Check for loose or corrodedconnections.

3 Overloads are auto reset. Check unit closely when unit comesback on line.

4. Repair or replace.5. Determine type and cause of shutdown and correct it before

resetting safety switch.6. None. Wait until unit calls for cooling.7. Repair or replace coil.8. Check motor for opens, short circuit or burnout.9 Check all wire junctions. Tighten all terminal screws.

1. Check setting of expansion valve.2 Relocate, add or remove hangers.3 Replace.

1 Purgee the noncondensables.2. Remove excess.3. Open valve.4. Adjust FanTrol settings.5. Check electrical circuit.6 Clean coil.

1 Check condenser control operation.2. Open valve.3. Check for leaks. Repair and add charge.4. See corrective steps for low suction pressure below.5. See corrective steps for failure of compressor to load.

1. Reduce load or add additional equipment.2. Check remote bulb. Regulate superheat.3. See corrective steps for failure of compressor to load

1 Check for leaks. Repair and add charge.2 Clean chemically.3 Replace.4 Clean strainers.5 Check and reset for proper superheat.6 Check means for regulating condensing temperature.7 See corrective steps for failure of compressor to unload.8 Adjust flow9 To troubleshoot take pressure drop across vessel and consult

factory to obtain design pressure drop for that vessel.

1 Replace.2 Replace.3 Replace.4 Reset thermostat setting to fit application.

1. Replace2 Adjust flow.

1. Clean.2. Check crankcase heater. Reset expansion valve tor higher

superheat. Check liquid line solenoid valve operation.3. Repair or replace. Keep valve closed except when taking read-

ing.4 Replace.5. Replace.6. Reverse direction of compressor rotation.7 Replace compressor.8 Add oil.9 Check and tighten system.

10. Replace gasket.11 Adjust thermal expansion valve.12 Adjust flow.13 Open valve.

1. Check for leaks and repair. Add refrigerant2 Replace compressor.3. Adjust superheat.4. Replace crankcase heater.

continued on next page

Page 45 / IM 268

6. High ambient temperature around the overload relay.7. Failure of second starter to pull in on part winding start system.

Thermal P r o t e c t o r1. Operating beyond design conditions

Switch Open2. Discharge valve partially shut.3. Blown valve plate gasket.

1. Check supply voltage for excessive line drop.2. Replace compressor motor.3. Check all connections and tighten.4. See corrective steps for high discharge pressure.5. Check supply voltage. Notify power company. Do not start

until fault is corrected.6. Provide ventilation to reduce heat.7. Repair or replace starter or time delay mechanism.

1. Add facilities so that conditions are within allowable limits2. Open valve.3. Replace gasket.

Product WarrantyMcQuay International, hereinafter referred to as the “Com-pany,” warrants that it will provide, at the Company’s op-tion, either free replacement parts or free repair of compo-nent parts in the event any product manufactured by theCompany and used in the United States proves defective inmaterial or workmanship within twelve (12) months from ini-tial start-up or eighteen (18) months from the date shippedby the Company, whichever comes first. For additional con-sideration, McQuay warrants that for four (4) years followingthe initial warranty period it will provide, at the Company’soption, free replacement parts for the motor compressor, or,free replacement for any integral component of the motor-compressor which proves defective in material or workman-ship. For an additional consideration, McQuay warrants thatfor nine (9) years following the initial warranty period it willprovide free replacement of the heat exchanger in gas-firedor oil-fired furnaces which proves defective in material andworkmanship. (Extended warranties for motor-compressorsand heat exchangers are not applicable unless separatelypurchased.)

To obtain assistance under this parts warranty, or ex-tended motor-compressor warranty, simply contact the sell-ing agency. For McQuay, BarryBlower and JennFan brandnames, contact McQuay International, Warranty Claims De-partment, PO. Box 1551, Minneapolis, MN 55440, telephone(612) 553-5330.

This warranty constitutes the buyer’s sole remedy. It isgiven in lieu of all other warranties. There is no implied war-ranty of merchantability or fitness for a particular purpose.In no event and under no circumstances shall the Company

be liable for incidental or consequential damages, whetherthe theory be breach of this or any other warranty, negli-gence or strict tort.

This parts warranty and the optional .extended warran-ties extend only to the original user. Of course, abuse, mis-use, or alteration of the product in any manner voids theCompany’s warranty obligation. Neitherthe parts or extendedwarranty obligates the Company to pay any labor or servicecosts for removing or replacing parts, or any shippingcharges. Refrigerants, fluids, oils, and expendable items suchas filters are not covered by this warranty.

The extended warranties apply only to integral compo-nents of the motor-compressor or heat exchanger, not torefrigerant controls, electrical controls, or mechanical con-trols, or to failures caused by failure of those controls.

Attached to this warranty is a requirement for equipmentcontaining motor-compressors and/or furnaces to reportstart-up information. The registration form accompanyingthe product must be completed and returned to the Com-pany within ten (10) days of original equipment start-up. Ifthat is not done, the date of shipment shall be presumed tobe that is not done, the date of shipment shall be presumedto be the date of start-up and the warranty shall expire twelve(12) months from that date.

No person (including any agent, salesman, dealer or dis-tributor) has authority to expand the Company’s obligationbeyond the terms of this express warranty, or to state thatthe performance of the product is other than that publishedby the Company.

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