Types—ground source heat pump

There are three types of ground-source heat pump: closed loop, open loop and direct expansion.

Open loop
This type of heat pump uses a lake, river or another body of water to exchange heat. The unit draws water directly to the heat exchanger, where heat is extracted. The system discharges the water either to an above ground body of water or back underground through a well.

Closed loop
Most closed-loop pumps circulate an antifreeze solution through a closed loop, usually made of plastic tubing, which is buried in the ground or submerged in water. A heat exchanger transfers heat between the refrigerant in the heat pump and the antifreeze solution in the closed loop. The loop can be in a horizontal, vertical, or pond/lake configuration.

Direct exchange
In this system, a refrigerant circulates through a continuous loop of copper tubing placed in the ground. It uses a relatively shorter and smaller set of buried tubing, reducing installation costs.