Geothermal Comes in More Than One Flavor

Geothermal heat pumps remove heat from one place and transfer it to another. They use the earth, or water in the earth, for their heat source and heat sink.

This heat for the earth comes from the earth’s crust. In fact, less than 4 percent of the stored energy in the earth’s crust comes from its hot molten center.

Since the tax credit program became available, all types of geothermal options have been on the minds of the building community. Direct GeoExchange technology uses copper refrigerant lines buried in the ground with refrigerant flowing through them, rather than a water or glycol heat exchange fluid. These buried copper pipes, or earth loops, act as the evaporator when in the heating mode. When in the cooling mode, the buried copper pipes act as the condenser.

Direct GeoExchange is a term used by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and the Air Conditioning, Heating and Refrigeration Institute (AHRI). (For the purposes of this story, all discussion about earth loops refer to direct GeoExchange technology.)