The heating process involves extracting heat energy from the ground and moving it into the building. Transferring heat from the earth into the building requires a cycle of evaporation, compression, condensation and expansion. A refrigerant is used as the heat transfer medium.
The heating cycle begins as cold, liquid refrigerant passes through a water-to-refrigerant heat exchanger and absorbs heat from the low temperature source (earth loop fluid or well water). As the heat is absorbed, the refrigerant evaporates into a gas. This gaseous refrigerant then passes through a compressor, where it is pressurized, raising its temperature to over 180° F. The hot gas then circulates through the refrigerant-to-air heat exchanger, where heat is removed as the cooler return air passes over it.
Now heated, this warm air is delivered into the building by way way of the blower and duct system. Upon releasing its heat energy into the air, the refrigerant returns to the water-to-refrigerant heat exchanger, where the process is repeated.
A by-product of the heating function is the production of hot water, delivered to the water heater by the way of a small pump.