GEOTHERMAL

Geothermal Basics

Geothermal systems, or ground source heat pumps, take advantage of the 45-55 degree F ambient temperature of the earth just six feet below ground level. This temperature is brought to the desired temperature through a compressor and circulation system. Geo-thermal systems do not qualify for NYSERDA subsidy, but they do qualify for federal and state tax credit. Systems are now available for homes as well as for much larger installations.

HOW IT WORKS

Geothermal heat pumps consist of three basic parts: 1) the ground heat exchanger; 2) the heat pump unit; and 3) pipes for water-based systems and duct work for air-based systems. The heat exchanger is either drilled vertically into the ground, or laid horizontally in a trench or pond. There are several possible installations: Horizontal loops are installed in trenches five feet or more deep where soil conditions allow for economical excavation. Horizontal loops take up more land area than any other loop type. Vertical loops are drilled where land area is limited.

Pond loops are installed in water at least eight feet deep and transfer heat or cooling to and from the pond. An average home would require approximately 900 feet of coiled pipe and ½ acre of water surface.

Open loop installations pump water from an underground aquifer through the geothermal unit and then discharge that water to a drainage ditch or pond. Like a closed loop installation, the geothermal unit processes heat and cooling from the water.