Ground source heat pumps upgrade low temperature heat extracted from the ground into higher temperature heat that can be used for space and water heating.  They work on the same principal as a refrigerator cooling circuit but in reverse.  A ground source heat pump takes low temperature heat from the ground or ground-water and ‘upgrades’ it to a higher temperature to provide space heating and/or hot water.  In a typical system, for every unit of electrical energy used to drive the system, between 3 and 5 units of heat are produced.

The ground source can be Closed loop, where same fluid is continually cycled through buried pipe system, or Open Loop when ground water is pumped from water wells through system and then returned back to ground water system down another well.