How Geothermal Works

A geothermal system consists of a geothermal heat transfer unit inside a building, which is connected to a ground loop consisting of pipes buried in the earth outside the house or sometimes to a well.

For a movie about how geothermal works, please select the appropriate link:

If you have a DSL or Cable connection:	56k Modem Connection
1024 x 768 resolution or above	1024 x 768 resolution or above
800 x 600 resolution or below	800 x 600 resolution or below

Heating: A Water/antifreeze solution circulating through the ground loop absorbs the heat from the ground and flows back into the house at ground temperature. The geothermal unit uses refrigerant technology to extract heat from the circulating water and to move it to a heat exchanger which conveys the heat to the distribution system; forced air, radiant floor, baseboard or any combination of these. Geothermal units are also capable of heating domestic hot water at a fraction of the cost of conventional water heaters.

Cooling: Water circulates through the loop and enters the house at ground temperature. The geothermal unit reverses direction from the heating mode and extracts heat from the house and moves it into the circulating water. The warmer water returns to the ground loop where the heat is absorbed and stored in the earth. This constitutes a type of 'thermal battery' which stores free summer heat in the ground which can be extracted by the geothermal system in the winter and moved back in the house.

Closed Loop options: Loops can be buried in trenches or pits, however, if yard space or obstructions do not allow this then drilled wells may be used.

Open loop option: If flows are sufficient for geothermal designs, water wells can be used to provide water to the geothermal unit and then discharged back into the ground.

Pond loop option: Closed loops can be designed to be placed into ponds if the body of water can meet minimum volume, depth and quality criteria. Supply and return pipes are run underground to the pond and coiled in circles at least eight feet under the surface of the water. This method is subject to approval by local authorities.

Figures courtesy of the U.S.Department of Energy

For more information visit:
www.geoexchange.org
www.eere.energy.gov/RE/geo_heat_pumps.html
www.econar.com