What is GeoExchange? - Page 4
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Making Hot Water
GeoExchange systems can also provide all or part of a household’s hot water. This can be highly economical, especially if the home already has a GeoExchange system, hence a ground loop, in place.
One economical way to obtain a portion of domestic hot water is through the addition of a desuperheater to the GeoExchange unit. A desuperheater is a small, auxiliary heat exchanger that uses superheated gases from the heat pump’s compressor to heat water. This hot water then circulates through a pipe to the home’s water heater tank. In summer, when the GeoExchange system is in the cooling mode, the desuperheater merely uses excess heat that would otherwise be expelled to the loop. When the GeoExchange unit is running frequently, homeowners can obtain all of their hot water in this manner virtually for free. A conventional water heater meets household hot water needs in winter if the desuperheater isn’t producing enough, and in spring and fall when the GeoExchange system may not be operating at all.
Because GeoExchange systems heat water so efficiently, many manufacturers today are also offering triple function GeoExchange systems. Triple function systems provide heating, cooling and hot water. They use a separate heat exchanger to meet all of a household’s hot water needs.
The Earth Connection
Once installed, the loop in a GeoExchange system remains out of sight beneath the Earth’s surface while it works unobtrusively to tap the heating and cooling nature provides. The loop is made of a material that is extraordinarily durable but which allows heat to pass through efficiently. This is important so it doesn’t retard the exchange of heat between the Earth and the fluid in the loop. Loop manufacturers typically use high-density polyethylene, a tough plastic. When installers connect sections of pipe, they heat fuse the joints. This makes the connections stronger than the pipe itself. Some loop manufacturers offer up to 50-year warranties. The fluid in the loop is water or an environmentally safe antifreeze solution that circulates through the pipes in a closed system.
Another type of geothermal heating and cooling is Direct GeoExchange (DX) systems, which utilize copper piping placed underground. As refrigerant is pumped through the loop, heat is transferred directly through the copper to the earth.
To ensure good results, the piping should be installed by professionals who follow procedures established by the International Ground Source Heat Pump Association (IGSHPA). Installers should be certified by IGSHPA or be able to show equivalent training by manufacturers or other recognized authorities at a recognized institution, such as one of the many regional GeoExchange training centers located throughout the United States.
