How It Works: Open Loop Systems
While the majority of geothermal installations use a closed loop system, another option is an open loop system. Instead of using an antifreeze solution sealed inside the buried piping, an open loop system uses water from a surface or underground source - such as a pond, lake or well. The water is pumped into the heat pump unit where the heat is extracted; the water is then discharged back into the original source. Well water designs are the most common and most cost-effective. The well supplies both household water and water for the heat pump. Approximately three gallons per minute of well water are needed per ton of cooling capacity. A 3,000-square-foot, well-insulated home would typically require 10 to 15 gallons per minute. Water quality is an important issue with open-loop systems. Mineral deposits can build up inside the heat exchanger, iron and other impurities can clog a return well, and organic matter from ponds and lakes can quickly damage a geothermal system. Water should be tested for acidity, mineral content and corrosiveness. |
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Learn more about:Working With It: Designing an Open Loop System Working With It: Installing an Open Loop System |
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Brochures and fact sheets:GeoThermal: Bringing Comfort to Your World |
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