A Primer on Geothermal Home Heating

Heat Pumps: Pump Free Heat from the Earth

Modern and efficient geothermal heating systems that harvest free heat from the earth are becoming increasingly popular as a method of providing domestic heating.

Vast amounts of heat from the sun is stored in the earth at all times, waiting to be tapped as a ready source of free,  clean, and renewable energy.

Geothermal heat is extracted from the earth by essentially the same mechanical process used in any domestic refrigerator or freezer. In a home appliance, the circulation of refrigerant absorbs heat from the food storage compartment and the heat is moved outside of the appliance. In a geothermal heating system, heat energy is absorbed from the earth and transferred into the residence.

Operating a geothermal system involves pumping a liquid, usually an alcohol/water mixture, through pipes buried in the earth. The liquid absorbs ground heat, which is then subsequently extracted by a "heat pump" and heat exchanger system that uses common mechanical refrigeration equipment including a separate refrigerant loop, a compressor, condenser, and a heat exchanger similar to a common radiator. The "ground heat" is extracted from the circulating coolant and transferred by a heat exchanger to the refrigerant loop. The heat is then transferred to a water or hot air exchanger, and distributed throughout the residence by forced air or circulated hot water.

Domestic potable hot water may be heated and is usually available with the installation of a heat pump system. Highly efficient residential air conditioning is also offered using the same equipment, simply by reversing the process and sending heat from the building back into the earth.