Geothermal heat pumps are considered ground source heat pumps (GSHPs) and they are electrically powered systems that tap the stored energy of the greatest solar collector in existence, the earth. These systems use the earth's relatively constant temperature to provide heating, cooling, and hot water for homes and for commercial buildings.

A geothermal pump design consisting of ground source pump units are typically in the range of 20% to 40% more efficient than conventional air conditioning systems. If you are designing one of these systems in the northeast, more than likely you will need a second source of heat, such as a small boiler that will provide additional heat that will be required when the outdoor temperature drops below 30 degrees. This second source of heat will supplement the heat that is being provided by the geothermal heat pumps.

There are two major piping systems in the overall design. One system called the earth coupling system is the outdoor piping system that is located below the surface of the earth. The other system is the indoor piping system that is connected to geothermal heat pump units that are located indoors. These indoor heat pumps provide either warm air for heating or cool air for cooling through a duct distribution system. The two piping systems are interconnected and both systems require circulating pumps.

When the heat pumps are in the heating mode they extract the heat from the earth and transfer this heat to the air distribution system. When a geothermal heat pump is in the cooling mode they extract heat from the air distribution system by cooling the air and transfer this heat back to the earth through the underground piping system.

There are two different types of piping loops. There is what is called the open piping loop similar to an open well where the water is exposed to the atmosphere, and there is the closed piping loop where the piping system is completely closed and not exposed to the atmosphere.

For design in a closed loop, the outdoor underground piping can be located horizontally in trenches or vertically in what is called a bore hole. Horizontal piping requires more land and depending on the type of soil and rock formation can be expensive. Vertical piping typically is a 6" hole that is drilled into the ground with a special drill and the hole is usually 300 to 400 feet deep. An average size home may require anywhere between 2 and 4 bore holes. A commercial building will require many more bore holes.

Many utility companies offer financial incentives for the installation of these geothermal systems to help offset the higher costs for these system compared to a more conventional air conditioning system. The federal government is also offering tax incentives for a geothermal heat pump design.

A geothermal pump design is very reliable and will provide many years of efficient heating and air conditioning for your home or your office building.