During the winter, the heat pump absorbs heat from the ground and uses it to warm the air in your home. In the warmer summer months, the processed is reversed, taking heat from your home and transferring it back into the ground.

The basic elements of a geothermal system include:

• Underground loops of plastic piping;

• A liquid antifreeze solution;

• A heat pump; and

• An air distribution system.

The loops of piping are buried in the ground near your home or business, either vertically or horizontally. That ground loop is connected to a pumping module inside your home.  The pump circulates a mixture of water and the antifreeze through the ground loop, where it absorbs heat from the earth.

When the heated liquid reaches the heat pump inside your home, the heat is multiplied and used to warm the air inside the air-handling system. A blower sends the warmed air throughout the building through ductwork.

• Underground loops of piping act as a heat exchanger. When the liquid antifreeze solution passes through the loops, it absorbs heat from the ground, which causes it to evaporate.

• An indoor heat pump unit includes the condenser coils. When the heated antifreeze vapor passes through the coils, it gives up its heat to the surrounding air and condenses back into a liquid.

• An air-handling system takes the heated air and moves it through ductwork to individual rooms.

During the summer, a reversing valve switches the indoor coil to act as the evaporator and the underground pipes to act as the condenser.  All components of a geothermal system - except the underground loops - are placed inside a building, usually in the basement, garage or crawl space. Because they're indoors, the compressor and other vital parts are protected, with most having a life span of 20 years or more.

Not all geo systems are alike - most provide summer air conditioning, but some models are designed only for winter heating.  Geothermal heat pumps also can be different in the way they're designed. Self-contained units combine the blower, compressor, heat exchanger and coil in a single cabinet.

De-superheaters

You can save even more energy and money by using your geothermal system to heat your water.  A de-superheater is a small refrigerant-to-water heat exchanger that can be added to a heat pump. It heats water with energy that would otherwise by given up by the heat pump's condenser.

A de-superheater can provide useful high-efficiency water heating. However, it provides hot water only when the system to which it's attached is operating; backup water heating is needed at other times.  For example, a de-superheater on a typical residential geothermal heat pump wouldn't heat water during spring and fall, when the full system isn't running.  But when it is running, you can take advantage of virtually free water heating for several weeks or even months each year.

Most manufacturers offer de-superheaters as a factory-installed option. If you have an even greater need for high-efficiency water heating, other options include dedicated heat pump water heaters and multi-function, full-condensing water heating systems.  Your contractor can help you determine which add-on water heating components are right for your needs.

Ductwork and insulation

If you're considering installing a geothermal system in your existing home or business, ductwork and insulation will play a big role.  If you have existing ductwork, it will most likely work for your new geothermal system. Your contractor can help you determine what modifications are needed.

If your home or business doesn't have an existing air distribution system (if you're replacing a boiler system, for example), ductwork or in-floor radiant heating must be installed. The difficulty will depend on how your structure was built.

Insulation is another key factor. Geothermal heat pumps will reduce your heating and cooling costs regardless of how well your home or business is insulated.  However, maximum insulation and weatherizing will help you realize the most energy savings from your high-efficiency geothermal system.