A: Ground water is attractive as a heat exchange medium in residential and commercial space conditioning. By using a geothermal heat pump, ground water can serve as a heat source (for heating) and a heat sink (for cooling).

The temperature of the ground water is nearly the same year-round, regardless of the temperature extremes on the surface. Thus, it is warmer than the outside air in winter and cooler in summer. Since GeoExchange unit capacity and efficiency vary significantly with the heat source/sink temperature (or temperature difference between the source/sink and conditioned space), a geothermal heat pump system offers considerable advantages over the more widely used air-to-air heat pump. Water will hold five times more heat than an equal weight of air and its heat content does not vary with its temperature. Air yields very little heat at temperatures below 25°F and will accept very little heat in the cooling cycle at temperatures above 85°F.

The only qualifications for the use of ground water with a geothermal heat pump system are that it must be abundant, of high quality, pumping costs must be reasonable, and conditions and regulatory requirements conducive to efficient discharge.