Geothermal
Heat from the Earth, or geothermal — Geo (Earth) + thermal (heat), is an enormous, underused heat and power resource that is clean (emits little or no greenhouse gases), reliable (average system availability of 95%).
Geothermal heat pumps (GHPs) use the natural heat storage capacity of the earth or ground water to provide energy efficient heating and cooling. These systems draw heat from, or release heat to, the earth, which has moderate temperatures year round.
Geothermal heat pumps use the relatively constant temperature of the ground or water several feet below the earth’s surface as source of heating and cooling. Geothermal heat pumps are appropriate for retrofit or new homes, where both heating and cooling are desired. In addition to heating and cooling, geothermal heat pumps can provide domestic hot water. They can be used for virtually any size home or lot in any region of the U.S.
A geothermal heat pump system consists of indoor heat pump equipment, a ground loop, and a flow center to connect the indoor and outdoor equipment. The heat pump equipment works like a reversible refrigerator by removing heat from one location and depositing it in another location. The ground loop, which is invisible after installation, allows the exchange of heat between the earth and the heat pump.
Ground loops can be installed in a vertical well or a horizontal loop. Vertical wells are usually more expensive and used where space is limited. The length of loop pipe required will vary with soil type, loop configuration, and system capacity. Loop length can range from 250 to 1,000 feet per ton of capacity.
Special heat pump features can include variable speed blowers and multiple-speed compressors. These features can improve comfort and efficiency in areas where heating and cooling loads are quite different. Add-on features include the capability to produce hot water.
