McQuay MHC Standard Range User Manual

IM 985-1 / Page 33 of 36
Figure 26. Cooling Mode
Return Air
Reversing Valve
Conditioned Air
(Cooling)
Thermal
Expansion Valve
Coaxial Heat
Exchanger
Blower
Coil – Air to Refrigerant
Heat Exchanger
Water In
Water Out
Sensing Bulb and
Capillary Tube
Compressor
Figure 27. Heating Mode
Return Air
Thermal
Expansion Valve
Coaxial Heat
Exchanger
Reversing Valve
Conditioned Air
(Heating)
Blower
Water In
Water Out
Sensing Bulb
and Capillary Tube
Compressor
Coil – Air to Refrigerant
Heat Exchanger
Cooling Refrigeration Cycle
WhenthewallthermostatiscallingforCOOLING,thereversingvalvedirectstheowoftherefrigerant,ahotgas,
leaving the compressor, to the water-to-refrigerant heat exchanger. Here the heat is removed by the water and the
hotgascondensestobecomealiquid.Theliquidthenowsthroughathermalexpansionmeteringsystemtothe
air-to-refrigerant heat exchanger coil. The liquid then evaporates becoming a gas, at the same time absorbing heat
andcoolingtheairpassingoverthesurfacesofthecoil.Therefrigerantthenowsasalowpressuregasthroughthe
reversing valve and back to the suction side of the compressor to complete the cycle.
Heating Refrigeration Cycle
WhenthewallthermostatiscallingforHEATING,thereversingvalvedirectstheowoftherefrigerant,ahotgas,
leaving the compressor, to the air-to-refrigerant heat exchanger coil. Here the heat is removed by the air passing
overthesurfacesofthecoilandthehotgascondensestobecomealiquid.Theliquidthenowsthroughacapillary
thermal expansion metering system to the water-to-refrigerant heat exchanger. The liquid then evaporates becoming
agas,atthesametimeabsorbingheatandcoolingthewater.Therefrigerantthenowsasalowpressuregasthrough
the reversing valve and back to the suction side of the compressor to complete the cycle.
Typical Cooling and Heating Refrigeration Cycles

McQuay MHC Standard Range Specifications

General

Brand	McQuay
Model	MHC Standard Range
Category	Heat Pump
Language	English