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How does a geothermal heating and cooling system work ? Outdoor temperatures fluctuate with the changing seasons but underground temperatures don't. Four to six feet below the earth's surface, temperatures remain relatively constant year round. A geothermal system, which typically consists of an indoor unit and a buried earth loop, capitalizes on these constant temperatures to provide "free" energy. In winter, fluid circulating through the system's earth loop absorbs stored heat and carriers it indoors. The indoor unit compresses the heat to a higher temperature and distributes it thoughouts the building. In summer, the system reverses, pulling heat from the building, carrying it through the earth loop and depositing it in the cooler earth.
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Animated diagram of heating cycle of geothermal system
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Animated diagram of cooling cycle of geothermal system
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Horizontal loops are often considered when adequate land surface is available. Pipes are placed in trenches, in lengths that range from 100 to 300 feet.
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These are ideal choices when available land surface is limited. Drilling equipment is used to bore small-diameter holes from 75 to 500 deep.
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These use groundwater as a direct energy source. In ideal conditions, an open-loop application can be the most economical type of geothermal loop.
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These are very economical to install when a body of water is available, because excavation cost are virually eliminated. Coils of pipe are simply placed on the bottom of the pond or lake.
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