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8/14/2019 Liquid Chillers Rev
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J.ILANGUMARANJ.ILANGUMARAN
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Liquid Chilling SystemLiquid Chilling System
A liquid chilling system cools water, brine,A liquid chilling system cools water, brine,or other secondary coolant for airor other secondary coolant for airconditioning or refrigeration.conditioning or refrigeration.
The system may be either factory assembledThe system may be either factory assembledand wired or shipped in sections forand wired or shipped in sections forerection in the fielderection in the field
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Components of chillers (vapor compressionComponents of chillers (vapor compressionsystem)system)
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Chilled Water SystemChilled Water System
Air Handling unit Circulating Pumps
Condenser
Chiller - Pump Evaporator
Chiller
Chilled Water Headers
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Components of vapor compression systemComponents of vapor compression system
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Chilled Water SystemChilled Water SystemChilled Water SystemChilled Water SystemChilled Water SystemChilled Water SystemChilled Water SystemChilled Water System
Chiller Yard Pump
Room
HT
OT
PD
To Hotel Tower 450Dia
To Office Tower 400Dia
To Podium 250Dia
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Chiller YardChiller YardChiller YardChiller Yard
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Multiple Chiller SystemMultiple Chiller System
Parallel chilled water flowParallel chilled water flow
arrangementarrangement
Series water flow arrangementSeries water flow arrangement
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Parallel chilled water flow arrangement
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Series water flow arrangement
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Type Of ChillersType Of Chillers
Based OnBased On
Condensing MediaCondensing Media
Air cooledAir cooled
Water cooledWater cooled
Based onBased on
CompressorCompressor
ReciprocatingReciprocating
CompressorCompressor
Screw CompressorScrew Compressor
CentrifugalCentrifugal
CompressorCompressor
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Chiller packageChiller package
Hermetically sealed Compressor & Motor,Hermetically sealed Compressor & Motor,
Condenser, Expansion device & Evaporator, interCondenser, Expansion device & Evaporator, inter--connected to form refrigeration cycle withconnected to form refrigeration cycle with
Fully charged refrigerant.Fully charged refrigerant.
Safety & operational controls.Safety & operational controls.
Lubrication system.Lubrication system.
Operation monitoring devices.Operation monitoring devices.
Control panel duly wired.Control panel duly wired.
Starter with Disconnect switch duly wiredStarter with Disconnect switch duly wired
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ChillersChillers
AirAir--cooled Reciprocating Chiller ORcooled Reciprocating Chiller OR
Water cooled Reciprocating ChillerWater cooled Reciprocating Chiller
AirAir--cooled Screw Chiller OR Watercooled Screw Chiller OR Water
cooled Screw Chillercooled Screw ChillerAirAir--cooled Centrifugal Chiller ORcooled Centrifugal Chiller OR
Water cooled Centrifugal ChillerWater cooled Centrifugal Chiller
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Chiller with Reciprocating CompressorChiller with Reciprocating Compressor
1.1. Semi Hermetic Reciprocating compressorSemi Hermetic Reciprocating compressor
2.2. MufflerMuffler3.3. Fan & condenser coilFan & condenser coil
4.4. Filter drierFilter drier
5.5. Liquid Line sight glassLiquid Line sight glass
6.6. Moisture indicatorMoisture indicator7.7. Expansion valveExpansion valve
8.8. DxDx--EvaporatorEvaporator
9.9. Control PanelControl Panel
10.10. StarterStarter
11.11. ControlsControls
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Chiller with CentrifugalChiller with Centrifugal
CompressorCompressorSemi Hermetic Centrifugal compressorSemi Hermetic Centrifugal compressor
Fan & condenser coilFan & condenser coilLiq. Line sight glassLiq. Line sight glass
Moisture indicatorMoisture indicator
Fixed orifice assemblyFixed orifice assembly
Flooded EvaporatorFlooded Evaporator
External Lubrication systemExternal Lubrication system
External Capacity control systemExternal Capacity control system
Motor cooling systemMotor cooling system
Control PanelControl Panel
StarterStarter
ControlsControls
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Chiller with ScrewChiller with Screw
CompressorsCompressorsSemi Hermetic Screw compressorSemi Hermetic Screw compressor
Oil SeparatorOil SeparatorFan & condenser coilFan & condenser coil
Receiver/SubReceiver/Sub--cooling coilscooling coils
Filter drierFilter drier
Liq. Line sight glassLiq. Line sight glass
Moisture indicatorMoisture indicator
Expansion valveExpansion valve
DxDx--EvaporatorEvaporator
Lubrication systemLubrication system
Control PanelControl Panel
StarterStarter
ControlsControls
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Basis of DesignBasis of Design
The Chilled Water System has beenThe Chilled Water System has been
designed to produce the chilled waterdesigned to produce the chilled water
at following so as to achieve theat following so as to achieve the
comfort conditionscomfort conditionsby Air conditioningby Air conditioning
system at floors.system at floors.
Entering Chilled Water Temp. : 55Entering Chilled Water Temp. : 55FF
Leaving Chilled Water Temp.Leaving Chilled Water Temp. : 45: 45FF
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Variable Speed DriveVariable Speed Drive
All the chilled water pumps areAll the chilled water pumps are
provided with a microprocessor based,provided with a microprocessor based,
pulse width modulated, adjustablepulse width modulated, adjustable
frequency AC drive.frequency AC drive.
The drive controls AC motor.The drive controls AC motor.
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Chilled Water systemChilled Water system
OperationOperation-- LogicLogic
The whole system is automatic thruThe whole system is automatic thru
Building Management System to achieveBuilding Management System to achievethe specified conditions at floors.the specified conditions at floors.
Once temperature is achieved in conditionOnce temperature is achieved in condition
space the motorized 2space the motorized 2--way valve closesway valve closeswhich in turn increases the difference inwhich in turn increases the difference in
pressure between supply & Return pipes.pressure between supply & Return pipes.
Reduction in speed reduces the chilledReduction in speed reduces the chilled
water flow in the system and save thewater flow in the system and save the
energy.energy.
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Chilled Water system OperationChilled Water system Operation--
LogicLogic
Once load in condition space increases,Once load in condition space increases,two way valves opens thus reduces thetwo way valves opens thus reduces the
pressure difference between supply &pressure difference between supply &
return pipes.return pipes.
Increase in speed, increases the ChilledIncrease in speed, increases the Chilled
flow to meet the requirement of conditionflow to meet the requirement of condition
spacespace..
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PumpsPumps-- Automatic ShutdownAutomatic Shutdown
The VFD shuts down the pump shouldThe VFD shuts down the pump shouldany of the following happens:any of the following happens:
Over TemperatureOver Temperature
Motor OverloadMotor Overload
High Motor CurrentHigh Motor Current
Motor GroundMotor Ground
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Chiller principleChiller principle
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Reciprocating ChillersReciprocating Chillers
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Refrigeration cycleRefrigeration cycle
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Refrigeration cycleRefrigeration cycle
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RefrigerationCycleRefrigerationCycle
Motor Compressor
MeteringDevice
Condenser
T
0C
on
ditio
ne
dS
pace
Retu
rnair
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Reciprocating compressors
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Reciprocating CompressorReciprocating Compressor
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Semihermetic reciprocating compressorsSemihermetic reciprocating compressors
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Semihermetic reciprocating compressorsSemihermetic reciprocating compressors
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Thermostatic expansion valveThermostatic expansion valve
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Thermostatic expansion valveThermostatic expansion valve
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Returning discharge to suction
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Capacity controlCapacity control Controlling suction pressure by throttling;Controlling suction pressure by throttling;
Controlling discharge pressure;Controlling discharge pressure;
Returning discharge gas to suction;Returning discharge gas to suction;
Adding reexpansion volume;Adding reexpansion volume;
Changing the stroke;Changing the stroke;
Opening a cylinder discharge port to suction whileOpening a cylinder discharge port to suction whileclosing the port to discharge manifold;closing the port to discharge manifold;
Changing compressor speed;Changing compressor speed;
Closing off cylinder inlet, andClosing off cylinder inlet, and
Holding the suction valve openHolding the suction valve open
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Factors Affecting the performance ofFactors Affecting the performance of
Refrigeration unitRefrigeration unit
Discharge pressureDischarge pressure
Out door air temperatureOut door air temperature
Air circulation thruAir circulation thru
condensercondenser
Condenser fins & tubeCondenser fins & tubeconditioncondition
Space between chillersSpace between chillers
Condenser fansCondenser fans
Excess refrigerantExcess refrigerant Evaporator pressureEvaporator pressure
Lack of refrigerantLack of refrigerant
Less water flowLess water flow
Erratic operation ofErratic operation of
Lubrication systemLubrication system
Low oil pressureLow oil pressure
Oil filter chokeOil filter choke
Quality & Accuracy ofQuality & Accuracy of
controls and Sensorscontrols and Sensors Calibration & settingCalibration & setting
Proper installationProper installation
Routine & preventiveRoutine & preventive
maintenancemaintenance
TimelyTimely
ProperlyProperly
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Factors Affecting theFactors Affecting the
performance ofperformance ofAir & water side systemAir & water side system
Air balancingAir balancing
Supply air flowSupply air flow
Return air flowReturn air flow
Grills and damperGrills and damper
adjustmentadjustment Fresh air flowFresh air flow
Dampers adjustmentDampers adjustment
AHU performanceAHU performance
Filters conditionFilters condition
Cooling coilCooling coil
Belts & pulleysBelts & pulleys
DampersDampers
Quality,Accuracy andQuality,Accuracy and
setting of Thermostats,setting of Thermostats,Humidistat and SensorsHumidistat and Sensors
Chilled water distributionChilled water distribution
StrainersStrainers
Flow control ValvesFlow control Valves
Pump performancePump performance
Chiller performanceChiller performance
Routine & preventiveRoutine & preventivemaintenancemaintenance
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Air Cooled CondenserAir Cooled Condenser
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E F
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DxDx EvaporatorEvaporator --Coil & FinsCoil & Fins
TypeType
DX E tDX E t Sh ll &T bSh ll &T b
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DX EvaporatorDX Evaporator--Shell &TubeShell &Tube
typetypeWater flow thru the shell.
Refrigerant is in tubes.
DX E aporatorDX Evaporator Shell &TubeShell &Tube
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DX EvaporatorDX Evaporator-- Shell &TubeShell &Tube
typetypeWater flow thru the shell
Refrigerant is in tubes
C i i lC iti l F t
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Critical FactorsCritical Factors
Shell & Tube EvaporatorsShell & Tube EvaporatorsQuality of watersQuality of waters
CleanedCleaned
Chemically treatedChemically treated
Velocity of water should not be higherVelocity of water should not be higher
than recommendedthan recommended Proper setting of Expansion valveProper setting of Expansion valve
Adequate water flowAdequate water flow
Proper installation of Sensors /ThermistorProper installation of Sensors /Thermistor
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Flooded EvaporatorsFlooded EvaporatorsIn flooded type evaporator aIn flooded type evaporator a
constant Refrigerant liquid level isconstant Refrigerant liquid level ismaintained.maintained.
A float valve / Level switches areA float valve / Level switches are
used as metering device to maintainused as metering device to maintainthe constant level.the constant level.
TypesTypes
Coil & Fins typeCoil & Fins typeShell & Tube typeShell & Tube type
Fl d d E tFlooded E aporator
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Flooded EvaporatorFlooded Evaporator
Coil & Fins typeCoil & Fins type
Fl d d E tFl d d E t
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Flooded EvaporatorFlooded Evaporator
Shell & Tube TypeShell & Tube Type
Orifice Assembly
Distributor
Tubes
From CondenserTo Compressor
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Metering DevicesMetering DevicesCapillary tubeCapillary tube
Fixed orifice typeFixed orifice type
Float valveFloat valve
Automatic expansion valveAutomatic expansion valveThermostatic expansion valveThermostatic expansion valve
Electronic expansion valveElectronic expansion valve
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Automatic expansion valveAutomatic expansion valveAutomatic expansion valveAutomatic expansion valveAutomatic expansion valveAutomatic expansion valveAutomatic expansion valveAutomatic expansion valve
It allows the flow ofIt allows the flow of
refrigerant torefrigerant tomaintain the constantmaintain the constant
pressure inpressure in
evaporator.evaporator.
It does not allow theIt does not allow therefrigerant flow torefrigerant flow to
maintain the Suctionmaintain the Suction
superheat.superheat.
Thermostatic ExpansionThermostatic Expansion
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Thermostatic ExpansionThermostatic Expansion
valvevalve
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Thermostatic Expansion valveThermostatic Expansion valve
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Electronic Expansion ValveElectronic Expansion Valve
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Sensing Bulb FixingSensing Bulb Fixing
Smaller diameter 1Smaller diameter 1Inch and belowInch and belowsuction linesuction line
Sensing bulb shouldSensing bulb should
be on topbe on topAbove 1 Inch dia,Above 1 Inch dia,
4 O4 O Clock Position.Clock Position.
Sensing Bulb shouldSensing Bulb shouldbe fully covered bybe fully covered byinsulating materialinsulating material..
dP i d i
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Protective devicesProtective devices
A highA high--pressure cutout.pressure cutout.HighHigh--temperature control devices to protect againsttemperature control devices to protect against
overheating and oil breakdown.overheating and oil breakdown.
Motor over temperature protective devicesMotor over temperature protective devices LowLow--pressure protection may be provided forpressure protection may be provided for
Suction gas and compressorSuction gas and compressor
Time delay, or lockouts with manual resets,Time delay, or lockouts with manual resets,prevents damage to both compressor motor andprevents damage to both compressor motor andcontactors from repetitive rapidcontactors from repetitive rapid--starting cyclesstarting cycles
Low voltage and phase loss or reversal protectionLow voltage and phase loss or reversal protection
is used on some systems. Phase reversalis used on some systems. Phase reversalprotection is used with multiprotection is used with multi--phase devices tophase devices toensure the proper direction of rotation.ensure the proper direction of rotation.
Suction line strainer.Suction line strainer.
Testing of Positive Displacement Refrigerant CompressorsTesting of Positive Displacement Refrigerant Compressors..
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g f p f g pg f p f g p
Compressor tests are of two types: the firstCompressor tests are of two types: the firstdetermines capacity, efficiency, sound level, motordetermines capacity, efficiency, sound level, motor
temperatures, etc.; the second predicts thetemperatures, etc.; the second predicts thereliability of the machine.reliability of the machine.
Standard rating conditions, which are usuallyStandard rating conditions, which are usuallyspecified by compressor manufacturers, includespecified by compressor manufacturers, includethe maximum possible compression ratio, thethe maximum possible compression ratio, themaximum operating pressure differential, themaximum operating pressure differential, themaximum permissible discharge pressure, and themaximum permissible discharge pressure, and the
maximum inlet and discharge temperaturemaximum inlet and discharge temperature Lubrication requirementsLubrication requirements
Power requirements for compressor startingPower requirements for compressor starting
Reciprocating ChillersReciprocating Chillers ControlsControls
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Reciprocating ChillersReciprocating Chillers ControlsControls
Discharge Pressure Control (High Pressure Control)Discharge Pressure Control (High Pressure Control)
Its function is to switch off the compressor, Once dischargeIts function is to switch off the compressor, Once dischargepressure exceeds the prepressure exceeds the pre--determineddetermined set pressureset pressure..
Set PointSet Point Cut outCut out -- 425 (+ or425 (+ or 6 ) Psig with R6 ) Psig with R--22 Refrigerant22 Refrigerant
Cut InCut In -- 320 (+ or320 (+ or 20) Psig20) Psig
Low Pressure Control (Depends upon Manufacturer)Low Pressure Control (Depends upon Manufacturer) Its function is to unload the compressor, once Suction /Its function is to unload the compressor, once Suction /
Evaporator pressure decreases to pre set pressure. Some timeEvaporator pressure decreases to pre set pressure. Some timeused to switch off the compressor.used to switch off the compressor.
Set PointSet Point Cut out 30 (+ orCut out 30 (+ or -- 5) Psig with R5) Psig with R--22 refrigerant.22 refrigerant.
Cut In 45 (+ orCut In 45 (+ or 5) Psig.5) Psig.
Reciprocating ChillersReciprocating Chillers ControlsControls
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Reciprocating ChillersReciprocating Chillers ControlsControls
Low Water Temperature ControlLow Water Temperature Control
Its function is to stop the refrigeration by stopping the compreIts function is to stop the refrigeration by stopping the compressor, oncessor, onceevaporator water temperature goes down below Set point so as toevaporator water temperature goes down below Set point so as to avoidavoidfreezing of water in the evaporator of chiller. Some time, it isfreezing of water in the evaporator of chiller. Some time, it is called ascalled as
AntiAnti--Freeze.Freeze.
Set Point 34 to 36Set Point 34 to 36 oo FF
Low Refrigerant Temperature ControlLow Refrigerant Temperature Control
It is used for not allowing the refrigerant temperature to go bIt is used for not allowing the refrigerant temperature to go below Setelow Setpoint, so as to avoid freezing of water and as well as loosing tpoint, so as to avoid freezing of water and as well as loosing theheefficiency of chiller.efficiency of chiller.
Flow ControlFlow Control
Its function is to ensure the adequate water flow through evapoIts function is to ensure the adequate water flow through evaporator.rator.Once flow decreases below set point, The switch will actuate andOnce flow decreases below set point, The switch will actuate and givegivealarm / stop signal to control panel, to avoid lower water tempealarm / stop signal to control panel, to avoid lower water temperature orrature orfreezing of water in evaporatorfreezing of water in evaporator
Reciprocating ChillersReciprocating Chillers ControlsControls
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Oil pressure differential switchOil pressure differential switch
It is used to ensure proper lubrication of bearingsIt is used to ensure proper lubrication of bearingsand other moving parts of compressor. To ensureand other moving parts of compressor. To ensureproper lubrication, a pressure difference is to beproper lubrication, a pressure difference is to bemaintained between oil pump pressure and crankmaintained between oil pump pressure and crankcase pressure. Once Differential pressure is lowercase pressure. Once Differential pressure is lower
than the preset differential pressure, It will actuatethan the preset differential pressure, It will actuateand alarm /stop the compressor operation.and alarm /stop the compressor operation.
Set pointSet point 6 to 10 Psig6 to 10 Psig-- DifferentialDifferential
Ground Current SafetyGround Current Safety
It opens on sensing a current to ground inIt opens on sensing a current to ground incompressor winding exceeds the 2.5 Amps.compressor winding exceeds the 2.5 Amps.
Reciprocating ChillersReciprocating Chillers ControlsControls
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In Adequate air flow thru condenserIn Adequate air flow thru condenser
Condensing Pressure will increase.Condensing Pressure will increase.
Load on compressor increases.Load on compressor increases.
Power consumption will increase.Power consumption will increase. Cooling capacity will reduce.Cooling capacity will reduce.
Leaving chilled water temperature will remain high.Leaving chilled water temperature will remain high.
Inadequate chilled water flow through evaporatorInadequate chilled water flow through evaporator Low suction pressure & Low evaporating temperature.Low suction pressure & Low evaporating temperature.
Liquid floodLiquid flood--back to compressor and may damageback to compressor and may damagecompressor discharge reeds (In Reciprocating compressor).compressor discharge reeds (In Reciprocating compressor).
May damage the Helical of screw compressor.May damage the Helical of screw compressor. Ice formation may occur and burst the evaporator.Ice formation may occur and burst the evaporator.
Cut out 30 (+ orCut out 30 (+ or -- 5) Psig with R5) Psig with R--22 refrigerant.22 refrigerant.
Cut In 45 (+ orCut In 45 (+ or 5) Psig.5) Psig.
Reciprocating ChillersReciprocating Chillers ControlsControls
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p gp g
NonNon-- Condensable gases in the systemCondensable gases in the system
Condensing Pressure will be high.Condensing Pressure will be high.
Load on compressor increases and compressorLoad on compressor increases and compressorwill be very hot.will be very hot.
Power consumption will be high.Power consumption will be high.
Cooling capacity will reduce.Cooling capacity will reduce.
Leaving chilled water temperature will remainLeaving chilled water temperature will remainhigh.high.
Poor cooling in conditioned space.Poor cooling in conditioned space.
Refrigerant ChargeRefrigerant Charge
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g gg g
Less chargeLess charge Compressor suction pressure will be low.Compressor suction pressure will be low.
Evaporator pressure and temperature will be low.Evaporator pressure and temperature will be low.
Heavy flashing and ice formation will occur at expansionHeavy flashing and ice formation will occur at expansionvalve, as a result lesser liquid refrigerant shall be availablevalve, as a result lesser liquid refrigerant shall be available
for actual refrigeration.for actual refrigeration.
BeingBeing low evaporator pressure & temperature, Any moisturelow evaporator pressure & temperature, Any moisture
present in refrigerant will freeze expansion valve orifice andpresent in refrigerant will freeze expansion valve orifice andrestrict the refrigerant flow.restrict the refrigerant flow.
Lower cooling capacity.Lower cooling capacity.
Over chargeOver charge
Higher head pressure and higher suction pressure.Higher head pressure and higher suction pressure. Load on compressor, will draw more current andLoad on compressor, will draw more current and
unnecessary High power consumption.unnecessary High power consumption.
Liquid flood back to compressor and can damage dischargeLiquid flood back to compressor and can damage dischargereeds.reeds.
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Centrifugal ChillersCentrifugal Chillers
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Working Of centrifugal Chiller
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Refrigeration cycleRefrigeration cycle
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Refrigeration cycleRefrigeration cycle
(With Centrifugal Compressor(With Centrifugal Compressor))
Centrifugal ChillerCentrifugal ChillerCentrifugal ChillerCentrifugal ChillerCentrifugal ChillerCentrifugal ChillerCentrifugal ChillerCentrifugal Chiller
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Centrifugal ChillerCentrifugal ChillerCentrifugal ChillerCentrifugal ChillerCentrifugal ChillerCentrifugal ChillerCentrifugal ChillerCentrifugal Chiller
(Water Cooled)(Water Cooled)(Water Cooled)(Water Cooled)(Water Cooled)(Water Cooled)(Water Cooled)(Water Cooled)
Centrifugal CompressorCentrifugal Compressor
CondenserCondenser
--Shell & TubeShell & Tube
Orifice AssemblyOrifice Assembly--11
EconomizerEconomizer
Orifice AssemblyOrifice Assembly--22 Flooded EvaporatorFlooded Evaporator
Lubrication SystemLubrication System
Motor Cooling SystemMotor Cooling System Control PanelControl Panel
StarterStarter
ControlsControls
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CompressorCompressorCompressorCompressorCompressorCompressorCompressorCompressor
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CompressorCompressorCompressorCompressoreeee
Compressor &Compressor &
Motor casing.Motor casing. IIstst stage impellerstage impeller
IIIIndnd stage impellerstage impeller
Volute casingsVolute casings
Thrust bearingThrust bearing
Journal bearingsJournal bearings
High speed gearsHigh speed gearsassembly Inner oilassembly Inner oil
guardsguards
Gear spray nozzlesGear spray nozzles Motor stator & rotorMotor stator & rotor
Suction inlet guideSuction inlet guide
vane & actuatorvane & actuator
Orifice AssemblyOrifice AssemblyOrifice AssemblyOrifice AssemblyOrifice AssemblyOrifice AssemblyOrifice AssemblyOrifice Assembly
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Orifice AssemblyOrifice AssemblyOrifice AssemblyOrifice AssemblyOrifice AssemblyOrifice AssemblyOrifice AssemblyOrifice Assembly
It is a assembly of twoIt is a assembly of twoplates having nos. ofplates having nos. of
orificesorifices
Liquid refrigerantLiquid refrigerant
pressure reduces whilepressure reduces while
passing thru it.passing thru it.
Refrigerant flowRefrigerant flow
controlled based oncontrolled based ondifferential pressuredifferential pressure..
Orifice
From Condenser To Evaporator
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EconomizerEconomizer
This is a intermediate pressure chamber in whichThis is a intermediate pressure chamber in which
a intermediate pressure (Second stage suctiona intermediate pressure (Second stage suction
pressure) is maintained.pressure) is maintained.
The high pressure liquid refrigerant enters intoThe high pressure liquid refrigerant enters into
economizer through orifice plate assembly.Whileeconomizer through orifice plate assembly.While
liquid passing thru orifice assembly,a portion of itliquid passing thru orifice assembly,a portion of it
evaporates (flashes) by absorbing heat fromevaporates (flashes) by absorbing heat from
remaining liquid refrigerant and thus remainingremaining liquid refrigerant and thus remaining
liquid gets cooled.liquid gets cooled.
Evaporated refrigerant goes directly to 2nd stageEvaporated refrigerant goes directly to 2nd stage
impeller for recycling.impeller for recycling.
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Lubrication SystemLubrication System
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Lubrication SystemLubrication System
Oil SumpOil Sump
Oil HeaterOil Heater
Sight glassSight glass
ThermometerThermometer
Submersible OilSubmersible OilPumpPump
Oil PressureOil Pressure
regulatorregulator
Oil cooling coilOil cooling coil
Oil Filter & IsolatingOil Filter & Isolatingvalvevalve
Oil by pass valvesOil by pass valves
Oil pipingOil piping
TemperatureTemperature
sensorssensors
Motor Cooling SystemMotor Cooling SystemMotor Cooling SystemMotor Cooling SystemMotor Cooling SystemMotor Cooling SystemMotor Cooling SystemMotor Cooling System
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Motor Cooling SystemMotor Cooling SystemMotor Cooling SystemMotor Cooling SystemMotor Cooling SystemMotor Cooling SystemMotor Cooling SystemMotor Cooling System
The hermetic motor are cooled by liquidThe hermetic motor are cooled by liquid
refrigerant.refrigerant.Liquid refrigerant enters the motor housing thruLiquid refrigerant enters the motor housing thru
an orifice and flows into a chamber surroundingan orifice and flows into a chamber surrounding
the stator.the stator.The refrigerant flows from this chamber thru theThe refrigerant flows from this chamber thru the
motor stator,thus cooling the stator and rotor.motor stator,thus cooling the stator and rotor.
Liquid refrigerant evaporates by absorbing heatLiquid refrigerant evaporates by absorbing heatfrom stator and rotor.from stator and rotor.
Finally Liquid & vapor mixture drain back toFinally Liquid & vapor mixture drain back to
evaporator thru bottom pipes.evaporator thru bottom pipes.
Electrical SystemElectrical SystemElectrical SystemElectrical SystemElectrical SystemElectrical SystemElectrical SystemElectrical System
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Starter panelStarter panel
SwitchesSwitches FusesFuses
TransformerTransformer
StarStar--Delta starter forDelta starter forcompressor motorcompressor motor
DOL / StarDOL / Star--DeltaDelta
starter for fansstarter for fansOverload relaysOverload relays
TimersTimers
ContractorsContractors
Control panelControl panel
Control switchControl switch Control TransformerControl Transformer
FusesFuses
RelaysRelays
Microprocessor modulesMicroprocessor modules
Unit control modulesUnit control modules
TimersTimers
AntiAnti--Recycle TimerRecycle Timer
Coast down TimerCoast down Timer
Safety switches (Outside)Safety switches (Outside)
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Flow SwitchesFlow SwitchesFlow SwitchesFlow SwitchesFlow SwitchesFlow SwitchesFlow SwitchesFlow Switches
It is a combination of Microprocessor andIt is a combination of Microprocessor and
Flow sensor.Flow sensor.Function is to give alarm or stop signal toFunction is to give alarm or stop signal to
chiller once flow reduces below set point.chiller once flow reduces below set point.
Setting in % (Minimum 50 %).Setting in % (Minimum 50 %).Shall give alarm signal to BMS at alarmShall give alarm signal to BMS at alarm
setting.setting.
Shall stop the chiller at stop setting.Shall stop the chiller at stop setting.Modulate Chiller capacity suit toModulate Chiller capacity suit to
temperature outlet.temperature outlet.
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Low Pressure cut out SwitchLow Pressure cut out SwitchLow Pressure cut out SwitchLow Pressure cut out SwitchLow Pressure cut out SwitchLow Pressure cut out SwitchLow Pressure cut out SwitchLow Pressure cut out Switch
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Low Pressure cut out SwitchLow Pressure cut out SwitchLow Pressure cut out SwitchLow Pressure cut out SwitchLo essu e cu ou S cLow Pressure cut out SwitchLow Pressure cut out SwitchLo essu e cu ou S c
It is a combination ofIt is a combination of
microprocessor and sensor.microprocessor and sensor.Some times it is a pressure switch.Some times it is a pressure switch.
The function is to give alarm / stopThe function is to give alarm / stop
signal to compressor once thesignal to compressor once theevaporator pressure reduces below theevaporator pressure reduces below theset point.set point.
Set pointSet pointCut out 2.0 bar (RCut out 2.0 bar (R--12 & R12 & R--134a)134a)
Cut in 2.3 to 2.4 barCut in 2.3 to 2.4 bar
Winding Temperature SensorsWinding Temperature SensorsWinding Temperature SensorsWinding Temperature SensorsWinding Temperature SensorsWinding Temperature SensorsWinding Temperature SensorsWinding Temperature Sensors
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It is a combination of microprocessor andIt is a combination of microprocessor andsensor.sensor.
A sensor sense the temperature and giveA sensor sense the temperature and givesignal to microprocessor.signal to microprocessor.
Microprocessor compares this signal withMicroprocessor compares this signal withset point and give out put command toset point and give out put command tostop the compressor if temperature isstop the compressor if temperature ishigher than set point.higher than set point.
Set point 265 deg F.Set point 265 deg F. Will Stop Motor once motor temperatureWill Stop Motor once motor temperature
rises to set point and will give alarm signalrises to set point and will give alarm signal
to BMS.to BMS.
Current LimiterCurrent LimiterCurrent LimiterCurrent LimiterCurrent LimiterCurrent LimiterCurrent LimiterCurrent Limiter
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e L ee L ee L ee L e
Its function is to limit the currentIts function is to limit the current
drawn by motor within set point.drawn by motor within set point. Set point 85Set point 85--95 % of full load95 % of full load
amperes.amperes.
It will unload the compressor byIt will unload the compressor byclosing the suction vane damper andclosing the suction vane damper andover ride all inputs / feed back for:over ride all inputs / feed back for:
Opening the vane dampers .Opening the vane dampers .
Increasing the load on compressorIncreasing the load on compressor
Critical FactorsCritical FactorsCritical FactorsCritical FactorsCritical FactorsCritical FactorsCritical FactorsCritical Factors(Evaporator)(Evaporator)(Evaporator)(Evaporator)(Evaporator)(Evaporator)(Evaporator)(Evaporator)
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Soft & Clean water.Soft & Clean water.
Cleaned tubes.Cleaned tubes.
Adequate chilled water flow.Adequate chilled water flow.
Adequate refrigerant flow.Adequate refrigerant flow.
Sensors are fitted properly.Sensors are fitted properly.
Application of Silicon grease orApplication of Silicon grease or
alternative heat transfer paste.alternative heat transfer paste.Chilled water temperatures as designed.Chilled water temperatures as designed.
Critical FactorsCritical FactorsCritical FactorsCritical FactorsCritical FactorsCritical FactorsCritical FactorsCritical Factors
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(Motor Cooling System)(Motor Cooling System)(Motor Cooling System)(Motor Cooling System)(Motor Cooling System)(Motor Cooling System)(Motor Cooling System)(Motor Cooling System)
Adequate liquid refrigerant flowAdequate liquid refrigerant flow
Strainer (Filter cum drier)Strainer (Filter cum drier) Adjustment of Service valvesAdjustment of Service valves
Design condenser pressureDesign condenser pressure
Design evaporator pressureDesign evaporator pressure
ProblemProblemProblemProblemProblemProblemProblemProblem
Higher motor temperatureHigher motor temperature
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System BalanceSystem Balance a)a)CompressorCompressor-- Able to pump refrigerant at same rate atAble to pump refrigerant at same rate atwhich liquid ref. vaporizes in evaporatorwhich liquid ref. vaporizes in evaporator
b)Condenserb)Condenser-- Able to reject heat from ref.at same rate atAble to reject heat from ref.at same rate atwhich ii picks up heat in evaporator and compressorwhich ii picks up heat in evaporator and compressor
c)Throttlingc)Throttlingdevicedevice-- Able to feed liquid ref.to evaporator atAble to feed liquid ref.to evaporator atsame rate at which the refrigerant is vaporized in thesame rate at which the refrigerant is vaporized in the
evaporatorevaporator Interconnecting liquid, suction and suction linesInterconnecting liquid, suction and suction lines-- capablecapable
of handling the same rate of flow of liquid ref, lowof handling the same rate of flow of liquid ref, low
pressure vapor and high pressure vapour with a minimumpressure vapor and high pressure vapour with a minimumof pressure dropof pressure drop
Capacity controlCapacity control
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p y
ReciprocatingReciprocating
compressorcompressorVariable speed motorVariable speed motor
Compressor cylinderCompressor cylinder
unloadingunloadingHotgasHotgas bypassbypass
Centrifugal compressorCentrifugal compressor
Guide vanes (inlet ofGuide vanes (inlet ofimpeller )impeller )
Screw compressorScrew compressor
Slide valve methodSlide valve methodLift valve methodLift valve method
LubricationLubrication
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Adequate Oil ChargeAdequate Oil Charge Manufacturer recommended oil should be used.Manufacturer recommended oil should be used.
Recommended quantity of oil should be charged.Recommended quantity of oil should be charged.
Lubricating oil container should never be left open.Lubricating oil container should never be left open. Excess ChargeExcess Charge
Can cause hydraulic knocking and damage the pistons.Can cause hydraulic knocking and damage the pistons.
It will be difficult to monitor the lubrication system.It will be difficult to monitor the lubrication system. Under ChargeUnder Charge
Oil pump will not be able to build up the pressure.Oil pump will not be able to build up the pressure.
Poor lubrication will damage the moving parts ofPoor lubrication will damage the moving parts ofcompressor.compressor.
Centrifugal ChillerCentrifugal ChillerControlsControls
Flow switches / Flow Sensor & Microprocessor CombinationFlow switches / Flow Sensor & Microprocessor Combination
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It is a combination of Microprocessor and Flow sensor.It is a combination of Microprocessor and Flow sensor. Function is to give alarm or stop signal to chiller once flow reFunction is to give alarm or stop signal to chiller once flow reducesduces
below set point.below set point.
Setting in % (Minimum 50 %).Setting in % (Minimum 50 %).
Shall give alarm signal to BMS at alarm setting.Shall give alarm signal to BMS at alarm setting.
Shall stop the chiller at stop setting.Shall stop the chiller at stop setting.
Modulate Chiller capacity suit to temperature outlet.Modulate Chiller capacity suit to temperature outlet.
Oil Differential Pressure SwitchOil Differential Pressure Switch
Its function is to stop chiller once differential pressure betweIts function is to stop chiller once differential pressure between oilen oilsupply and compressor casing reduces below the differential setsupply and compressor casing reduces below the differential set point.point.
Normally set at 1.0 bar to 1.5 bar differential.Normally set at 1.0 bar to 1.5 bar differential.
Shall give Alarm signal to BMS at Alarm setting.Shall give Alarm signal to BMS at Alarm setting.
Will stop Chiller if differential pressure below set poinWill stop Chiller if differential pressure below set pointt
Centrifugal ChillerCentrifugal ChillerControlsControls
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High Oil Temperature SensorHigh Oil Temperature Sensor It is a combination of microprocessor and sensor or some time itIt is a combination of microprocessor and sensor or some time it is ais a
Temperature switch.Temperature switch.
The function is to give alarm / stop signal to compressor once oThe function is to give alarm / stop signal to compressor once oilil
temperature increases above set point.temperature increases above set point. Set point 180Set point 18000 F.F.
Will give alarm signal to BMS on rising oil temperature above seWill give alarm signal to BMS on rising oil temperature above settpoint.point.
May stop compressor if control circuit is made accordingly.May stop compressor if control circuit is made accordingly. High Pressure ControlHigh Pressure Control
t is a combination of microprocessor and pressure sensor.t is a combination of microprocessor and pressure sensor.
In some Chillers, it is a Pressure switch.In some Chillers, it is a Pressure switch.
The function is to give alarm / stop signal to compressor onceThe function is to give alarm / stop signal to compressor once thethedischarge pressure increases to set point.discharge pressure increases to set point.
Set point 12.0 to 12.5 (RSet point 12.0 to 12.5 (R--12) and 15.0 (R12) and 15.0 (R--134a).134a).
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Centrifugal ChillerCentrifugal ChillerControlsControls
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Chilled Water Temperature ControlChilled Water Temperature Control
It is a combination of Microprocessor and Temperature Sensor.It is a combination of Microprocessor and Temperature Sensor.
A sensor (installed in the outlet pipe of Evaporator) senses theA sensor (installed in the outlet pipe of Evaporator) senses the leaving chilledleaving chilled
water temperature and gives temperature signal to microprocessorwater temperature and gives temperature signal to microprocessor..
The Microprocessor compares this temperature signal with set temThe Microprocessor compares this temperature signal with set temperature.perature. According to difference, Microprocessor give output command to vAccording to difference, Microprocessor give output command to vane controlane control
modulating motor, either for closing or opening the vane to modmodulating motor, either for closing or opening the vane to modulate the flowulate the flowof refrigerant. Thus by it controls the capacity of Chiller.of refrigerant. Thus by it controls the capacity of Chiller.
Set Temperature generally 41 to 46Set Temperature generally 41 to 46
oo
FF Motor Winding Temperature SensorsMotor Winding Temperature Sensors
It is a combination of microprocessor and sensor.It is a combination of microprocessor and sensor.
A sensor sense the temperature and give signal to microprocessoA sensor sense the temperature and give signal to microprocessor.r.
Microprocessor compares this signal with set point and give outMicroprocessor compares this signal with set point and give out put commandput command
to stop the compressor if temperature is higher than set point.to stop the compressor if temperature is higher than set point.
Set point 265 deg F.Set point 265 deg F.
Will Stop Motor once motor temperature rises to set point andWill Stop Motor once motor temperature rises to set point and will give alarmwill give alarm
signal to BMSsignal to BMS
Centrifugal ChillerCentrifugal ChillerControlsControls
M t O L d P t tiM t O L d P t ti
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Motor Over Load ProtectionMotor Over Load Protection Its function is to protect compressor motor againstIts function is to protect compressor motor against
overloading.overloading.
Set point 95Set point 95--100 % full load Amperes.100 % full load Amperes.
It will stop compressor motor, once current drawn byIt will stop compressor motor, once current drawn bymotor increases to set point and remain for more than 30motor increases to set point and remain for more than 30--40 second.40 second.
Alarm signal will be given to BMS once it actuates.Alarm signal will be given to BMS once it actuates.
Current LimiterCurrent Limiter Its function is to limit the current drawn by motorIts function is to limit the current drawn by motorwithin set point.within set point.
Set point 80Set point 80--90 % of full load current.90 % of full load current.
It will unload the compressor by closing the suctionIt will unload the compressor by closing the suctionvane damper, and over ride all inputs for opening thevane damper, and over ride all inputs for opening thevane dampers for increasing the load on compressorvane dampers for increasing the load on compressor..
Centrifugal ChillerCentrifugal ChillerControlsControls
A ti RA ti R l Til Ti
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Anti ReAnti Re--cycle Timercycle Timer Its function is to ensure that chiller reIts function is to ensure that chiller re--start is not taking place before thestart is not taking place before the
Set time.Set time.
Once chiller stops either from controls or manually, It should nOnce chiller stops either from controls or manually, It should not take reot take re--start before a time recommended by manufacturer for the safety ostart before a time recommended by manufacturer for the safety off
Compressor & MotorCompressor & Motor.. Set time generally 15Set time generally 15 --20 Minutes.20 Minutes.
Coast Down TimerCoast Down Timer
Its function is to ensure that the Oil Pump is running for a cerIts function is to ensure that the Oil Pump is running for a certain periodtain period
even after chiller is given stop command either by controls or Meven after chiller is given stop command either by controls or Manualanualstop.stop.
As chiller has been given stop command either by controls or manAs chiller has been given stop command either by controls or manualualstop, The motor & impeller keeps rotating for some time due to istop, The motor & impeller keeps rotating for some time due to inertia.nertia.During this period, it is essential to provide lubrication to beDuring this period, it is essential to provide lubrication to bearing andaring and
rotating parts of Compressor & Motor.rotating parts of Compressor & Motor. Set time generally 3 minutesSet time generally 3 minutes (It is the time, Motor / Impeller takes in(It is the time, Motor / Impeller takes in
coming to idle condition after giving stop command).coming to idle condition after giving stop command).
PrePre--start Checksstart Checks
Check oil sump temperatureCheck oil sump temperature
Should beShould be 6060oo 7070oo CC
Start upStart up --ChillerChiller
Place system switch inPlace system switch in OFFOFF
positionposition Pl l h A O
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Should beShould be 6060oo -- 7070oo C.C.
Check oil levelCheck oil level
Should be visible 1/ 4 to 3/4 inShould be visible 1/ 4 to 3/4 in
lower glass.lower glass.
Check system pressureCheck system pressure
Should be below 8 Bar.Should be below 8 Bar.
Physical checkPhysical check -- CondenserCondenser
Check condenser fan and fanCheck condenser fan and fanbelts.belts.
Check chilled water flowCheck chilled water flow
Control panel reading (Control panel reading (
Microprocessor & Flow Sensor)Microprocessor & Flow Sensor)
Pressure drop methodPressure drop method
position.position. Place oil pump switch inPlace oil pump switch in AUTOAUTO
position.position.
Close the main disconnect switchClose the main disconnect switch(Make(Make ONON).).
Operate oil pump and fans onOperate oil pump and fans on
ManualManual to check operation.to check operation. Set the current limiterSet the current limiter %%
CurrentCurrent..
Suggest to setSuggest to set 75 to 80 %75 to 80 % initiallyinitiallyoror MinimumMinimum..
Set theSet the
Control TemperatureControl Temperature
atat
desired temperature.desired temperature.
Reset the safety controls or circuitReset the safety controls or circuitbreaker.breaker.
Place thePlace the Vane PositionVane Position switchswitchinin AutoAuto position.position.
Start Chiller by Putting the systemStart Chiller by Putting the systemswitch inswitch in ONON PositionPosition
Daily Operation Checks (Log Recommended by Manufacturer)
Parameter Normal operation Reading Actual Reading Actual reading
Ambient Condition DB & WB
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Chilled water Temperature Entering Leaving Temp Drop
Chilled water pressure Entering Leaving Pressure drop
Condenser Water Temperature Entering Leaving Temp. Rise
Condenser Water Pressure Entering Leaving Pressure drop
Evaporator Pressure
Discharge Pressure
oil pressureSupply to BearingsReturn from bearing
oil TemperatureSupply to BearingsReturn From bearing
Sump oil Temperature
% Vane opening
Amperes
Abnormal Sound or Noise
Maintenance (Weekly)Maintenance (Weekly)
Check Sump oil levelCheck Sump oil level Maintenance (Monthly)Maintenance (Monthly)
Perform weekly checksPerform weekly checks
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Check Sump oil level.Check Sump oil level. Oil should be visible inOil should be visible in
lower site glass.lower site glass.
Check liquid line siteCheck liquid line site
glasses.glasses. Check unit piping and coilsCheck unit piping and coils
for visible signs of leaks.for visible signs of leaks.
Listen and observe theListen and observe the
operation of the chiller foroperation of the chiller forusual sounds.usual sounds.
Check all operatingCheck all operatingpressure and temperaturepressure and temperature
againstagainst normal operatingnormal operatingcondition.condition.
Perform weekly checks.Perform weekly checks.
Check fan belt tension andCheck fan belt tension andwear.wear.
Check fan and fan motor forCheck fan and fan motor for
lubrication.lubrication. Check condenser condition,Check condenser condition,
If required clean the coil byIf required clean the coil by NUNU--coil/ calcoil/ cal--clean.clean.
Or follow individualOr follow individualmanufacturer recommendation.manufacturer recommendation.
Maintenance (Annual)Maintenance (Annual)
MechanicalMechanical
Perform weekly & monthlyPerform weekly & monthly ElectricalElectrical
Check physical condition ofCheck physical condition of
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Perform weekly & monthlyPerform weekly & monthlyinspection checks.inspection checks.
Clean the condenser coil byClean the condenser coil byrecommended chemical.recommended chemical.
Straighten the fins by NylonStraighten the fins by Nyloncomb.comb.
Change oil by approved oilChange oil by approved oilonly.only.
Be doubly sure about oilBe doubly sure about oil
quality and storage time.quality and storage time. Change oil filter.Change oil filter.
Check and change theCheck and change theliquid line filter of motorliquid line filter of motorcooling system.cooling system.
Clean the chilled water inletClean the chilled water inletstrainerstrainer
Check physical condition ofCheck physical condition ofthe components in starterthe components in starterpanel.panel.
Check physical conditionCheck physical condition
of all actuating components.of all actuating components. Terminal & Lugs condition.Terminal & Lugs condition.
Clean the contactor byClean the contactor byCommercial carbon tetraCommercial carbon tetrachloridechloride (CCL 100)(CCL 100) oror
equivalent.equivalent. Check for loose connection.Check for loose connection.
Check sensors.Check sensors.
Fill the conductive liquid inFill the conductive liquid in
thermothermo --well, if required.well, if required.
Periodic ChecksPeriodic Checks Leak checkLeak check
Purge operationPurge operation
System drynessSystem dryness L b i t l lL b i t l l
Inspection of starter contacts andInspection of starter contacts and
actionaction
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System drynessSystem dryness Lubricant levelLubricant level
Lubricant filter pressure dropLubricant filter pressure drop
Refrigerant quantity or levelRefrigerant quantity or levelSystemSystem pressures andpressures and
temperaturestemperatures Water flowsWater flows
Expansion valves operationExpansion valves operation
RegularlyRegularly Scheduled MaintenanceScheduled Maintenance
CondenserCondenser and lubricant coolerand lubricant coolercleaningcleaning
EvaporatorEvaporator cleaning on opencleaning on opensystemssystems
CalibratingCalibrating pressure, temperature,pressure, temperature,and flow controlsand flow controls
TighteningTightening wires and powerwires and power
connectionsconnections
actionaction Safety interlocksSafety interlocks Dielectric checking of hermetic andDielectric checking of hermetic and
open motorsopen motors Tightness of hot gas valveTightness of hot gas valve Lubricant filter and drier changeLubricant filter and drier change
AnalysisAnalysis of lubricant and refrigerantof lubricant and refrigerant Seal inspectionSeal inspection Partial or complete valve or bearingPartial or complete valve or bearing
inspection, as per manufacturerinspection, as per manufacturerssrecommendationsrecommendations
Vibration levelsVibration levels
Extended Maintenance ChecksExtended Maintenance ChecksCompressorCompressor guide vanes and linkageguide vanes and linkage
operation and wearoperation and wearEddyEddy current inspection of heatcurrent inspection of heat
exchanger tubesexchanger tubesCompressorCompressor teardown andteardown and
inspection of rotating componentsinspection of rotating components Other components asOther components as
recommended by manufacturerecommended by manufacture
Screw ChillersScrew Chillers
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Screw ChillersLiquid Chilling SystemLiquid Chilling System
A liquid chilling system cools water, brine,A liquid chilling system cools water, brine,or other secondary coolant for airor other secondary coolant for air
conditioning or refrigerationconditioning or refrigeration..
The system may be either factoryThe system may be either factoryassembled and wired or shipped inassembled and wired or shipped in
sections for erection in the field.sections for erection in the field.
Twin Screw Compressors
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Twin Screw Compressors
ComponentsComponents
of chillersof chillers
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Components of chillers Compressor (reciprocating, centrifugal orCompressor (reciprocating, centrifugal or
rotary),rotary),
Liquid cooler (evaporator),Liquid cooler (evaporator),
Condenser, a compressor drive, a liquidCondenser, a compressor drive, a liquid
refrigerant expansion or flowrefrigerant expansion or flow--controlcontroldevice, and a control center.device, and a control center.
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EconomizerEconomizer
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EconomizerEconomizerEconomizer is a separate vesselEconomizer is a separate vessel
containing the Electronic Expansioncontaining the Electronic Expansionvalve and a float valvevalve and a float valve
PurposesPurposes
It improves chiller capacity andIt improves chiller capacity andefficiencyefficiency
It provides compressor motor coolingIt provides compressor motor cooling
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Screw CompressorsScrew Compressors
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Both are conventionally used with fluidBoth are conventionally used with fluid
injection where sufficient fluid cools andinjection where sufficient fluid cools and
seals the compressorseals the compressor..
Screw compressors have the capability toScrew compressors have the capability to
operate at pressure ratios above 20:1operate at pressure ratios above 20:1
single stage.single stage.
The capacity range currently available isThe capacity range currently available is
from 20 to 1300 tonsfrom 20 to 1300 tons
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Single Screw Compressor
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Sequence of CompressionSequence of Compression
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SSuctionuction
CompressionCompression
DDischargeischarge
Compressor rotationCompressor rotation
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Compressor rotationCompressor rotationCompressor rotation in ScrewCompressor rotation in Screw
compressor is extremely importantcompressor is extremely importantOperation in the opposite direction, evenOperation in the opposite direction, even
momentarily, can cause serious rotormomentarily, can cause serious rotor
damage and must be avoideddamage and must be avoided
Mechanical FeaturesMechanical Features
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RotorsRotors
The screw rotor is normally made of castThe screw rotor is normally made of castironiron and the mating gate rotors are madeand the mating gate rotors are made
from an engineered plastic.from an engineered plastic.
The inherent lubricating quality of the plastic,The inherent lubricating quality of the plastic,as well as its compliant nature, allow theas well as its compliant nature, allow the
singlesingle--screw compressor to achieve closescrew compressor to achieve close
clearances with conventional manufacturingclearances with conventional manufacturing
practice.practice.
Mechanical FeaturesMechanical Features
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RotorsRotors
BearingsBearings EconomizersEconomizers
Economizers
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Hermetic CompressorsHermetic Compressors
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Hermetic screw compressors areHermetic screw compressors arecommercially available through 200 tons ofcommercially available through 200 tons of
refrigeration effect using Rrefrigeration effect using R--22. The hermetic22. The hermetic
motors can operate under discharge, suction,motors can operate under discharge, suction,
or intermediate pressure. Motor cooling canor intermediate pressure. Motor cooling canbe with gas, oil, and/or liquid refrigerant. Oilbe with gas, oil, and/or liquid refrigerant. Oil
separation for these types of compressorsseparation for these types of compressors
may be accomplished either with anmay be accomplished either with an
integrated oil separator or with a separatelyintegrated oil separator or with a separatelymounted oil separator in the systemmounted oil separator in the system..
Capacity ControlCapacity Control
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All positiveAll positive--displacement compressors, bothdisplacement compressors, both
speed modulation and suction throttling can bespeed modulation and suction throttling can be
used. Ideal capacity modulation for anyused. Ideal capacity modulation for anycompressor includescompressor includes
Continuous modulation from 100% to less thanContinuous modulation from 100% to less than
10%,10%,
Good partGood part--load efficiencyload efficiency
Unloaded startingUnloaded starting
Unchanged reliabilityUnchanged reliability
TwinTwin--screw compressorsscrew compressors
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Twin screw is the common designation forTwin screw is the common designation fordouble helical rotary screw compressors.double helical rotary screw compressors.
A twinA twin--screw compressor consists of twoscrew compressor consists of twomating helically grooved rotorsmating helically grooved rotors--malemale(lobes) and female (flutes or gullies) in a(lobes) and female (flutes or gullies) in a
stationary housing with inlet and outletstationary housing with inlet and outletgas ports.gas ports.
The flow of gas in the rotors is mainly inThe flow of gas in the rotors is mainly inan axial directionan axial direction
Sequence of Compression Process inSequence of Compression Process in
Twin Screw CompressorTwin Screw Compressor
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SuctionSuction
CompressionCompression DischargeDischarge
LubricantLubricant
b i i l d b f h f ll i h d
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Lubricant is cooled by one of the following methodsLubricant is cooled by one of the following methods
WaterWater--cooled using condenser water, evaporative condensercooled using condenser water, evaporative condenser
sump water, chilled water, or a separate watersump water, chilled water, or a separate water-- or glycolor glycol--toto--air cooling loopair cooling loop
AirAir--cooled using a lubricantcooled using a lubricant--toto--air heat exchangerair heat exchanger
RefrigerantRefrigerant--cooled (where lubricant cooling load is low)cooled (where lubricant cooling load is low)
Liquid injection into the compressorLiquid injection into the compressor Condensed refrigerant liquid thermal recirculationCondensed refrigerant liquid thermal recirculation
(thermosyphon), where appropriate, compressor head(thermosyphon), where appropriate, compressor head
pressure is availablepressure is available
Oil separatorsOil separators
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Efficient lubricant separators areEfficient lubricant separators are
required. The types and efficienciesrequired. The types and efficienciesof these separators vary according toof these separators vary according to
refrigerant and application. Fieldrefrigerant and application. Field
built systems requires better built systems requires betterseparation than complete factoryseparation than complete factory--
built systemsbuilt systems
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MotorComp
Control
Air cooled condenser
SCREW.CH.FLOW CYCLE
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Oil separator
Oil cooler
StrainerOil pump
Control
Evaporator
Filter coreReceiver
MotorComp
control
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Oil separator
oil cooler
strainer
oil pump
oil filtersGauge
Gaugecontrol
CAPACITY CONTROL
LUBRICATION SYSTEM
Capacities and Types AvailableCapacities and Types Available
Screw compressor liquid chillers are available as factoryScrew compressor liquid chillers are available as factory
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Screw compressor liquid chillers are available as factoryScrew compressor liquid chillers are available as factory--
packaged units from about 30 to 1250 Tons.packaged units from about 30 to 1250 Tons.
The following types of liquid chillers are generally used for aiThe following types of liquid chillers are generally used for airrconditioning:conditioning:
Up to 25 tonsUp to 25 tons Reciprocating or scrollReciprocating or scroll
25 to 80 tons25 to 80 tons Screw, reciprocating, or scrollScrew, reciprocating, or scroll
80 to 450 tons80 to 450 tons Screw, reciprocating, or centrifugalScrew, reciprocating, or centrifugal 200 to 1000 tons200 to 1000 tons Screw or centrifugalScrew or centrifugal
Above 1000 tonsAbove 1000 tons CentrifugalCentrifugal
Safety controlsSafety controls
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Lubricant failure switch,Lubricant failure switch, High discharge pressure cutout,High discharge pressure cutout,
Low suction pressure switch,Low suction pressure switch,
Cooler flow switch,Cooler flow switch,
High lubricant and discharge temperature cutout,High lubricant and discharge temperature cutout,
Hermetic motor inherent protection,Hermetic motor inherent protection,
Lubricant pump and compressor motor overloads,Lubricant pump and compressor motor overloads,
andand
Low lubricant temperature (flood back/dilutionLow lubricant temperature (flood back/dilutionprotection).protection).
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Starting of Screw compressorStarting of Screw compressor
The current limit relay protects against motorThe current limit relay protects against motor
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The current limit relay protects against motorThe current limit relay protects against motoroverload from higher than normal condensingoverload from higher than normal condensing
temperatures or lowtemperatures or low--voltage and also allows avoltage and also allows ademand limit to be set, if desired. An antire cycledemand limit to be set, if desired. An antire cycletimer is used to prevent overly frequenttimer is used to prevent overly frequentrecycling. Lubricant sump heaters are energizedrecycling. Lubricant sump heaters are energizedduring the off cycle. A hot gas capacity control isduring the off cycle. A hot gas capacity control isoptionally available and prevents automaticoptionally available and prevents automaticrecycling at norecycling at no--load conditions such as is oftenload conditions such as is oftenrequired in process liquid chilling. A suction torequired in process liquid chilling. A suction todischarge starting bypass sometimes aids startingdischarge starting bypass sometimes aids starting
and allows the use of standard starting torqueand allows the use of standard starting torquemotors.motors.
Starting of Screw compressorStarting of Screw compressor
Some units are equipped with electronicSome units are equipped with electronic
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Some units are equipped with electronicSome units are equipped with electronicregulators specially developed for theregulators specially developed for the
screw compressorscrew compressor These regulators include PI controlThese regulators include PI control
(Proportional(Proportional--Integrating) of the leavingIntegrating) of the leaving
brine temperature and such functions as brine temperature and such functions asautomatic/manual control, capacityautomatic/manual control, capacityindication, time circuits to preventindication, time circuits to preventfrequent recycling and to bypass thefrequent recycling and to bypass the
lubricant pressure cutout during startup,lubricant pressure cutout during startup,switch for unloaded starting, etc.switch for unloaded starting, etc.
Inspection or change outInspection or change out
timetabletimetable
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Shaft seals 1.5 to 4 yr InspectShaft seals 1.5 to 4 yr Inspect
Hydraulic cylinder seals 1.5 to 4 yrHydraulic cylinder seals 1.5 to 4 yr
ReplaceReplace
Thrust bearings 4.0 to 6 yrThrust bearings 4.0 to 6 yr
Shaft bearings 7 to 10 yr InspectShaft bearings 7 to 10 yr Inspect
Check preload via shaft end play every 6Check preload via shaft end play every 6months and replace as requiredmonths and replace as required
Capacity Slide ValveCapacity Slide Valve
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A slide valve for capacity control is a valveA slide valve for capacity control is a valve
with sliding action parallel to the rotorwith sliding action parallel to the rotor bores. They are placed within or close to bores. They are placed within or close to
the highthe high--pressure cusp region, face one orpressure cusp region, face one or
both rotor bores, and bypass a variable both rotor bores, and bypass a variableportion of the trapped gas charge back toportion of the trapped gas charge back to
suction, depending on their positionsuction, depending on their position
Capacity Lift ValveCapacity Lift Valve
Capacity lift valves or plug valves areCapacity lift valves or plug valves are
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Capacity lift valves or plug valves areCapacity lift valves or plug valves aremovable plugs in one or both rotormovable plugs in one or both rotor
bores (with radial or axial lifting bores (with radial or axial liftingaction) that regulate the actual startaction) that regulate the actual startof compression. These valves controlof compression. These valves control
capacity in a finite number of steps,capacity in a finite number of steps,rather than by the infinite control ofrather than by the infinite control ofa conventional slide valvea conventional slide valve
Chiller NumberChiller Number
NomenclatureNomenclature
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ExampleExample
0 6 N A 11 2 3 S 6 E A0 6 N A 11 2 3 S 6 E A
First three digits are the basic modelFirst three digits are the basic model 06N06N
Fourth digitFourth digit AA for Airfor Air--cooledcooledWW for Waterfor Water--cooledcooled
Fifth digit Type of RefrigerantFifth digit Type of Refrigerant 11for refrigerant 134afor refrigerant 134a
Sixth, Seventh and Eighth digits Compressor displacementSixth, Seventh and Eighth digits Compressor displacement
Ninth digit Electrical characteristicsNinth digit Electrical characteristics
Tenth digit Electrical FrequencyTenth digit Electrical Frequency
Eleventh digit Type of motor coolingEleventh digit Type of motor cooling EE forfor
economizedeconomized NN noneconomizednoneconomized
Twelfth digit PackagingTwelfth digit Packaging AA standard packagingstandard packaging BB
service packagingservice packaging
HVAC controlsHVAC controls
Automatic HVAC control systems are designed toAutomatic HVAC control systems are designed tomaintain temperature, humidity, pressure, flow,maintain temperature, humidity, pressure, flow,power lighting levels and safe levels of indoorpower lighting levels and safe levels of indoor
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power, lighting levels, and safe levels of indoorpower, lighting levels, and safe levels of indoorcontaminantscontaminants
Automatic control primarily modulates, stages, orAutomatic control primarily modulates, stages, orsequences mechanical and electrical equipmentsequences mechanical and electrical equipmentto meet load requirements and provide safeto meet load requirements and provide safe
operation of the equipment.operation of the equipment. It can use digital, pneumatic, mechanical,It can use digital, pneumatic, mechanical,
electrical, and electric control devises, andelectrical, and electric control devises, and
implies that human intervention is limited inimplies that human intervention is limited instarting and stopping equipment and adjustingstarting and stopping equipment and adjustingcontrol set points.control set points.
HVAC controlsHVAC controls
The sensor measuresThe sensor measures A controller can be inA controller can be in
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the controlled variablethe controlled variable
and transmits values toand transmits values tothe controllerthe controller
The controller comparesThe controller comparesthe value of thethe value of the
controlled variable withcontrolled variable withthe set point andthe set point andgenerates a signal to thegenerates a signal to the
controlled device forcontrolled device forcorrective action.corrective action.
the form of hardwarethe form of hardware
or software.or software.Thermostats,Thermostats,humidistat, andhumidistat, andpressure controls arepressure controls areexamples of hardwareexamples of hardwarecontrollers. Digitalcontrollers. Digitalalgorithms arealgorithms are
examples of softwareexamples of softwarecontrollers.controllers.
HVAC controlsHVAC controls
The set point is the desiredThe set point is the desired
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value of the controlledvalue of the controlled
variable.variable. The controller seeks toThe controller seeks to
maintain this set point.maintain this set point.
The controlled device reactsThe controlled device reactsto signals received from theto signals received from thecontroller to vary the flow ofcontroller to vary the flow ofthe control agentthe control agent
The controlledThe controlled
device may be adevice may be avalve, damper,valve, damper,heating element, or aheating element, or a
motor driving amotor driving apump or a fan.pump or a fan.
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ValvesValvesValvesValves
A singleA single--seated valve isseated valve isdesigned for tightdesigned for tight
A threeA three--way mixingway mixingvalve has two inlet andvalve has two inlet and
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designed for tightdesigned for tightshutoffshutoff
A doubleA double--sealed orsealed orbalanced valve isbalanced valve is
designed so that thedesigned so that the
media pressure actingmedia pressure actingagainst the valve disc isagainst the valve disc isessentially balanced,essentially balanced,reducing the operatorreducing the operator
force requiredforce required
valve has two inlet andvalve has two inlet and
one outlet connectionsone outlet connectionsand a doubleand a double--faced discfaced discoperating between twooperating between twoseatsseats
A threeA three--way divertingway divertingvalve has one inlet andvalve has one inlet andtwo outlet connectionstwo outlet connections
and two separate discsand two separate discsand seatsand seats
HVAC controlsHVAC controls
A thermistor is aA thermistor is ad hi d h
Preprogrammed controlPreprogrammed controlti k fiti k fi
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semiconductor thatsemiconductor that
changes electricalchanges electricalresistance withresistance withtemperature. It has atemperature. It has anegative temperaturenegative temperature
coefficient; i.e., thecoefficient; i.e., theresistance decreases as theresistance decreases as thetemperature increasestemperature increases
routines, known as firmware,routines, known as firmware,are typically stored inare typically stored inpermanent memory such aspermanent memory such asEEPROM (electronicallyEEPROM (electronicallyerasable programmable readerasable programmable readonly memory). To preventonly memory). To preventunauthorized alteration, theunauthorized alteration, theoperator can modify parametersoperator can modify parameterssuch as set points, limits, andsuch as set points, limits, andminimum off times within theminimum off times within the
control routines, but thecontrol routines, but theprogram logic cannot beprogram logic cannot bechanged without replacing thechanged without replacing thememory chips.memory chips.
HVAC controlsHVAC controls
DampersDampers Indoor Air QualityIndoor Air Quality
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DampersDampers
Humidity SensorsHumidity Sensors
Pressure TransmittersPressure Transmitters andand
transducerstransducers
Flow Rate SensorsFlow Rate Sensors
TransducersTransducers
Indoor Air QualityIndoor Air Quality
SensorsSensors Digital ControllersDigital Controllers
ThermostatsThermostats
PI ControllersPI Controllers