User guide

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Corporate Office: 724.584.5500  Instant Access 24/7 (Parts and Service): 800.458.1960  Parts and Service: 814.437.6861
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OperatingPrinciples
CoolantCircuit
Thecoolantpump,externaltothechiller,circulatescoolantthroughtheprocesspipingand
thenbacktothechiller.Uponenteringthechiller,thecoolantwillpassthroughaY‐Strainer
thatfilterstheprocessfluidbeforeenteringtheevaporator.Heattransferredfromthecoolant
totherefrigerantoccursintheevaporator.Varyingtheamountofheattransferredinthe
evaporatordeterminestheloadingofthecompressor,whichmaintainsthetemperature
setpointofthecoolantdeliveredtotheprocess.A“ProcessReturn”temperaturesensorsenses
thetemperatureofthecoolantasitenterstheevaporator.
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Afterleavingtheevaporator,thecoolantpassesbyaflowswitchandthe“ProcessSupply”
temperaturesensor.Thesensorsensesthetemperatureofthecoolantdeliveredtoprocess
andcommunicatesthistemperaturetothePLCcontroller.Thissensoristhecontrolsensorfor
thePLCcontrolsystem.
RefrigerantCircuit
Theheattransferredintheevaporatorfromthecoolanttotherefrigerantchangesthestateof
therefrigerantfromaliquidtoagas.Thisrefrigerantgasthenmovesfromtheevaporatorto
thecompressor.
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Thecompressoristheheartoftherefrigerationcircuit.Cool,low‐pressuregasentersthe
compressorandhot,high‐pressuregasexitsthecompressor.Sincethecompressorisnot100%
efficient,someextraheatgainoccursastherefrigerantiscompressed.
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Thehot,high‐pressuregasexitingthecompressorgoestothecondenser.Inwater‐cooled
condenserunits(EP2Wmodels),theheatistransferredfromtherefrigerantflowaroundthe
tubestothewaterthatisflowingthroughthetubes.Inair‐cooledcondenserunits(EP2A&
EP2Rmodels),theheatistransferredfromtherefrigerantinthefinnedtubestotheairthatis
flowingacrossthefinnedtubes.Astheheattransferoccurs,therefrigerantchangesfromagas
toaliquid.Thecondenserremovestheheatfromtheprocessloadandtheheatthatisadded
bythecompressor.
Afterleavingthecondenser,theliquidrefrigerantpassesthroughthefilterdryerandsight
glass.Thefilterdryerfiltersoutanyparticlesand/ormoisturefromtherefrigerant.Usethe
sightglasstomonitorthestreamofliquidrefrigerant.Theliquidrefrigerantthenpasses
throughthethermostaticexpansionvalve,whichmeterstheflowintotheevaporatorwhere
theprocessbeginsagain.
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Capacitycontrolisachievedbyredirectingsomeofthehotgasfromthecompressoroutlet
away
fromthecondenser.Thisgasismeteredthroughanelectronicallycontrolled,stepper
motordrivenHotGasBypassValve.Thehotgasisinjectedintotheevaporatorinlet,reducing
thechiller’scoolingcapacityduringlightloading.TheHotGasBypassValveisopenedbythe
PLCwhenthesupplywatertemperature
isbelowtheTemperatureSetpoint.