Specifications

IM 1060 / Page 29 of 32
Typical Cooling and Heating Refrigeration Cycles – Dual Compressors
Note: Typical temperature readings are at full load conditions at ISO-13256 for boiler-tower applications.
Figure 33: Cooling Refrigeration Cycle
WhenthewallthermostatcallsforCOOLING,thereversing
valve(de-energized)directstheowoftherefrigerant,ahotgas,
from the compressor to the water-to-refrigerant heat exchanger
(coaxial heat exchanger). There, the heat is removed by the water,
and the hot gas condenses to become a liquid. The liquid then
owsthroughathermalexpansionvalvetotheair-to-refrigerant
heat exchanger coil (evaporator). The liquid then evaporates and
becomes 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.
Figure 34: Heating Refrigeration Cycle
WhenthewallthermostatcallsforHEATING,thereversing
valve(energized)directstheowoftherefrigerant,ahotgas,
from the compressor to the air-to-refrigerant heat exchanger coil
(condenser). There, the heat is removed by the air passing over
the surfaces of the coil and the hot gas condenses and becomes a
liquid.Theliquidthenowsthroughathermalexpansionvalve
to the water-to-refrigerant heat exchanger (evaporator). The liquid
then evaporates and becomes 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.