How does a geothermal system work? The efficiency of the geothermal power is that it uses the stable temperature in the earth as a heat source, so the refrigerant is exchanging heat with water that is circulating through the ground.
A heat pump works on the same principal as the refrigerator. So, if you can picture a refrigerator continually chilling down your ice box. It can work also on reverse, so I can continually pump heat into a space. There is a refrigerant gas that's continually changing state; evaporating and condensing. When it changes state, that's how it gains its efficiency. A lot of heat is taken up or given off when the refrigerant changes state from a gas to a liquid and back to a gas.
