Geothermal heating and cooling takes proven heat pump technology and uses it to extract heat from the earth in winter to warm us and dissipates heat in summer to cool us. While the temperature of the soil to several feet below the surface varies with the seasons, below that depth the earth's temperature stays about the same. For example, in the Midwest this temperature is about 55 degrees Fahrenheit. This is much cooler than the outdoor air in summer and much warmer in the winter.
There are several types of systems to gather the heat from the ground. The most commonly used are: Closed Loop where a loop of pipe, usually of high-grade plastic, is buried in the ground, filled with water, an anti-freeze solution, or a refrgerant and connected to the heat pump.
The horizontal loop system in either straight pipe or slinky coils is installed in trenches typically dug 4 to 6 feet deep wherever space and soil conditions are suitable. The vertical loop goes down as needed - in some cases to depths of up to 250 feet. For commercial installations, a number of vertical loop heat exchangers are used.
|The aqua loop or pond loop system is placed on the bottom of a pond or in another convenient body of water. Another type is the direct expansion system in which a refrigerant is circulated in the buried piping, instead of water or antifreeze.|
Open Loop where water, pumped from a well or a body of water, passes through a heat exchanger in the heat pump system. This system requires a plentiful supply of high quality well or ground water and a good place for water disposal after the heat has been used.