Geothermal heat pumps take energy from the earth (land or large water source) and use it to heat and supply domestic hot water to a building. It relies on the fact that the earth's temperature is fairly constant throughout the year (12°C) below the frost line.

Unlike a traditional boiler, a geothermal heat pump does not create heat, rather it uses a small amount of energy (electricity) to transport heat from the heat source (earth) to the heat sink (building). The environmentally friendly anti freeze/water mixture runs through the plastic pipes in the earth picking up low grade heat. The heat pump uses a condenser, expansion vessel, evaporator and compressor vessel to extract the low grade heat from the water/anti freeze mix and turns it into high grade heat for the house heating system and domestic hot water. The heat pump can produce enough heat so that a boiler is not required! The process can also be reversed to provide cooling in the summer.

The most common types of closed loop geothermal systems are the horizontal loop, bore hole and Pond loop.

Here is an example of a bore hole loop.