A geothermal heating and cooling system consists of three main pieces of equipment:

• 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.

Desuperheaters

You can save even more energy and money by using your geothermal system to heat your water.

A desuperheater 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 desuperheater 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 desuperheater 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 desuperheaters 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.

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Learn more about:

How It Works: Anatomy of a Geothermal Heat Pump

How It Works: Concepts

Resources: Incentives & Financing

Resources: Dealer Locator

Insulating Your Home [PowerHouse: Home Comfort Tips]

Weatherizing Your Home [PowerHouse: Home Comfort Tips]

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Brochures and fact sheets:

Geothermal: Bringing Comfort to Your World
By Alliant Energy
[PDF format – 7 pages, 174kb]

More brochures and fact sheets….