Here Are the Facts on Earth Loops

Three Basic Geothermal Energy Sources
Closed-loop systems circulate a water-based solution through a "loop system " of small-diameter, high-density polythylene underground pipes. Closed-loop systems can be installed horizontally, vertically or in a pond. Open-loop systems use an existing water well or surface water. Whether the system is open or closed, heat is transferred to or from the structure, regardless of outdoor temperature, to provide year-round comfort.

	Boiler-Cooler Systems Typically, a boiler is employed to maintain closed loop temperatures above 60°F and a cooling tower to maintain loop temperatures below 90°F. These systems are applicable in medium to large buildings regardless of whether the load is heating or cooling dominated.
	Vertical Loops The ideal choice when available land surface is limited. Well drilling equipment is used to bore small-diameter holes from 100 to 400 feet deep.
	Pond (Lake) Loops Very economical to install when a large body of water is available. Coils of pipe or a submersed heat exchanger are simply placed in the pond or lake.
	Ground Water Systems In ideal conditions, an open-loop application can be the most economical type of geothermal system - utilizing well water, lake, ocean or other water source as a direct energy source.
	(Click on the loop diagrams for larger images)