A device that extracts heat from beneath the Earth is called a Geothermal Heat Pump (GHP). The GHP functions based on the principle that heat will move from higher to lower temperature materials, by either conduction or convention (air currents). These pumps absorb energy from both the ground and bodies of water and uses it to provide space and water heating. This is able to occur because the Earth absorbs 50% of the suns heat that reaches the Earth’s service.
Taking advantage of the earth’s ability to store thermal energy, ground source heating and cooling is inexpensive and environmentally friendly while still providing lots of heat. These pump systems can either pump heat from the ground into a building, or in warmer weather, from the building back into the ground. It doesn’t take much electricity to run the pumps and fans, along with a compressor.
GHPs utilize the relatively constant temperature of the ground or water several feet below the surface as a source of heating and cooling and are appropriate for both retrofit or new homes. In addition to space heating and cooling, geothermal heat pumps can provide hot water with virtually no additional energy requirements because GHPs don’t create heat; they merely move it from one area to another. This is a relatively new technology that can save homeowners money
It can cost several times to install a geothermal heating and cooling system, compared to the traditional kind. However, those costs are recovered over the next five to ten years, in the form of saving on energy costs. The interior components of these systems can easily last twenty-five years, and the piping in the ground can last fifty years. These systems are practical in most areas, and about 50,000 new systems are put in every year. They heat in the winter, and cool in the summer.
Quite a number of new residential systems come with desuperheaters, by which excess heat is transferred to the home’s hot water storage tank from the geothermal heat pump’s compressor, providing a highly efficient means of heating water. But in the spring and autumn, during which the geothermal heat pump system does not operate, the desuperheater will not provide hot water. However, because of the geothermal system’s significant advantage in efficiency compared to other water heating methods, ‘full demand’ systems using a separate heat exchanger to meet hot water needs cost-effectively are now being offered by some manufacturers.