The heat pump is the heart of any geothermal system. In the heating mode it functions to concentrate the thermal energy that has been collected from the ground and convert that raw energy into a usable form that can be distributed throughout the home to heat the various living spaces within the house. In the cooling mode the heat pump collects energy (excess heat) from within the house and transfers it back into the ground using the ground loop to carry this unwanted energy back into the ground.
Within the heat pump a refrigeration cycle is at work. Known as the Carnot Cycle, a heat pump functions on a thermodynamic principal called the latent heat of vapourization. A refrigerant material (410A) is circulated within the heat pump, repeatedly compressed and then expanded, thereby changing it from a liquid to vapour and then back again. This change of state either requires or gives off heat and provides the source of energy that is then used to heat or cool the home.
Heat pumps are extremely reliable mechanical pieces of equipment and require considerably less maintenance when compared to traditional furnaces. Additionally, there is no need for an outdoor AC unit since a heat pump functions as both a furnace and an air conditioning unit, contained within a single box. This further reduces the operating and maintenance costs of running a geothermal system since there is no equipment outside the house above the ground.