Because electricity is used only to transfer heat, not to produce it, the GHP will deliver 3 to 4 times more energy than it consumes. It can be effectively used over a wide range of earth temperatures. The GHP unit sits inside the home or building, at the site of a normal gas furnace. In a typical installation, a loop of plastic pipe is placed in a nearby vertical drill hole from one hundred to several hundred feet deep and the hole is backfilled with clay. There is no consumptive use of groundwater whatsoever, nor is there any contact between the solution in the plastic pipe and the earth or groundwater.
Installation easily conforms to local construction and well-drilling regulations.
Typical loop installations are warranteed for 50 years. GHPs have been installed in homes and buildings in the U.S. to mid-1990. Additional installations are being actively promoted by investor-owned utilities and rural electrical cooperatives as a means of promoting energy efficiency and better managing demand.