The heating process involves the extraction of heat energy from the ground, and moving it into the building. Transferring the heat from the earth to the building involves a cycle of evaporation, compression, condensation and expansion. A refrigerant is used as the heat transfer medium. The heating cycle starts 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). The refrigerant evaporates into a gas as heat is absorbed. The gaseous refrigerant passes through a compressor where the refrigerant is pressurized, raising its temperature to over 180° F. The hot gas then circulates through a 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 of the blower and the 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 continuously during the heating process. A by-product of the heating function is the production of hot water that is delivered to the water heater by way of a small pump.