Ground-source heat pumps (GSHPs), often known as a Geothermal heat pumps, extract heat from the earth around a home and transfer the heat into the house in the winter, providing space heat. Ground-source heat pumps consist of three parts: (1) pipes buried in the ground to draw heat from the earth, (2) the heat pump, and (3) a means of distributing heat in a house (a conventional heating system such as a radiant floor or forced-air heating system).

In the winter, ground-source heat pumps gather heat from the subsoil, well beneath the frost line where temperatures remain about 50°F (10°C) year round. Heat is collected from this massive heat sink by water or propylene glycol pumped through the underground network of pipes. The heat is then concentrated by the heat pump and transferred into a home.

How do heat pumps turn 50°F ground heat into 80° or 90°F (27° or 32°C) space heat? Ground-source heat pumps rely on refrigeration technology—refrigerants, gases, compressors, and pumps. Without getting too technical, the heat delivered to the heat pump causes the refrigerant in the unit to expand. The refrigerant is then sent to a compressor. Compressing the vaporized refrigerant releases heat. It is captured and transferred to the heating system while the refrigerant gas is recompressed and reused.

Heat pumps can also be used to draw heat from the groundwater or even surface waters, for example, a nearby lake or pond. These units are known as water-source heat pumps.

Pros and Cons of Ground-Source Heat Pumps

Ground-source heat pumps have many great features. Perhaps the most important is that they are extremely energy efficient. According to the United States Department of Energy (DOE) and Environmental Protection Agency (EPA), ground-source heat pumps are the most efficient, environmentally benign, and cost-effective space-heating and cooling system on the market today. These systems use relatively small amounts of electricity to power their pumps and compressors—about 25 to 50 percent less than conventional heating and cooling systems. Moreover, ground-source heat pumps require no additional fuel other than the heat they extract from the earth, which is free. Because of this, ground-source heat pumps offer the lowest carbon dioxide emissions of any conventional heating and cooling system on the market today.

Yet another advantage of ground-source heat pumps is that they can be installed in virtually any climate. Although they’re more expensive to install than conventional heating and cooling systems, efficiency gains pay for the additional costs in two to ten years. In addition, ground-source heat pumps carrying EPA’s Energy Star label can be financed with special Energy Star loans from banks and other financial institutions. Some of these loans offer a lower interest rate than you’d be able to get for a conventional heating system. Others allow longer repayment. Some combine both features. (For information on Energy Star loans, call 1-888-STAR-YES).

Another advantage of ground-source heat pumps is that they are more compact than conventional heating and air conditioning systems. They also have relatively few moving parts and typically require less maintenance than conventional heating and cooling systems. Underground piping is often warranted for 25 to 50 years.

Yet another advantage of ground-source heat pumps is that they are much less likely to set your home on fire, as they contain no flames. The absence of combustion also eliminates indoor air pollution.  ....read more