Geothermal

What is a geothermal heat pump?

A geothermal heat pump is a central heating and/or cooling system that pumps heat to or from the ground. It uses the earth as a heat source (in the winter) or a heat sink (in the summer). This design takes advantage of the moderate temperatures in the ground to boost efficiency and reduce the operational costs of heating and cooling systems. Geothermal heat pumps are also known by a variety of other names, including geoexchange, earth-coupled, earth energy or water-source heat pumps.

Are incentives available from the state or federal government?

YES. Home and commercial building owners who install geothermal heating and cooling systems are now eligible for federal tax incentives under the American Recovery and Reinvestment Act of 2009 (H.R. 1: Div. B, Sec. 1122, p. 46), which removed the maximum credit amount for all eligible technologies (except fuel cells) placed in service after 2008. The legislation offers a one-time tax credit of 30 percent of the total investment for residential ground-loop or groundwater geothermal heat pump installations, with no limit on the maximum credit.

To qualify for the tax credit, residential systems must meet Energy Star requirements. The contractor who sold and installed the product should list the purchase as a "geothermal heat pump" on the invoice and note that the unit "Exceeds requirements of the Energy Star program currently in effect." The home served by the system does not have to be the taxpayer's principal residence. The act also provides incentives forresidential wind and solar systems, biomass, and efficient appliances and vehicles. Some states offer tax incentives, and some utilities offer rebates or special electric rates. You should check with a contractor to find out what's available in your area.

Can geothermal cool as well?

It can do more than cool; it can make hot water, too. A simple switch at the thermostat reverses the process, allowing the geothermal system to provide cooling twice as efficiently as any other air conditioning system. In the process, the system provides virtually free hot water and superior home dehumidification plus, some units can make all of your hot water.

Are we going to be comfortable?

Probably more comfortable than ever. A geothermal system moves warm air throughout your home via a standard duct network. Because the system moves a larger volume of air, heat is more even throughout the home and the initial cold air blast common with fossil fuel furnaces is eliminated. It's also a great comfort to know that you've reduced your energy consumption while using a renewable source - the earth. And geothermal means a cleaner house because there is no soot from combustion, and increased air flow means increased filtration.

Can a geothermal system be added to my furnace?

Split systems can easily be added to existing furnaces for those wishing to have a dual- fuel system. Dual-fuel systems use the geothermal unit as the main heating source and a fossil fuel furnace as a supplement in extremely cold weather if additional heat is needed. Your electric utility may provide special rates for dual-fuel installations.

What does open-loop and closed-loop mean?

The heart of the geothermal systems is the ground loop. An open-loop geothermal system uses well water as a heat source. As the water passes through it, the system extracts heat, reducing the water temperature about 5 degrees F. The water is then returned to the earth, usually by running it on the ground and letting it seep into the aquifer. A closed-loop system extracts heat from the earth by a series of liquid-filled pipes buried in the ground. The plastic pipes are filled with water and antifreeze. The pipe used in closed loop systems is buried beneath the frost line. The pipe can also be run vertically in bored holes. A typical home will have about 2,000 running feet of pipe in the earth loop. The pipe can have a guaranteed lifetime of 50 years or more.

Do I need separate loops for heating and cooling?

No. The same loop works for both. All that happens when changing from heating to cooling is that the flow of heat is reversed.

How do geothermal owners feel about them?

State and national surveys show that over 90 percent of owners are very satisfied with their geothermal units. More than 95 percent said they would choose the system again and recommended it to others.

Is a geothermal heat pump difficult to install?

Most units are easy to install, especially when they are replacing another forced air system. They can be installed in areas unsuitable for fossil fuel furnaces because there is no combustion, thus, no need to vent exhaust gases. Ductwork must be installed in homes that don't have an existing air distribution system. The difficulty of installing ductwork will vary and should be assessed by a contractor.

How is heat made from cold well water or the frozen earth?

The earth is a wonderful source of heat. Just ask the burrowing animals that depend on it for warmth in the winter. In fact, the earth stores 47 percent of the solar energy that reaches us, making it a natural source of heat for our homes, if we can get it out. And we can. Geothermal heating and cooling systems, also called earth loop, or ground-coupled heat pumps, move the heat from the ground into your home using the same technology your refrigerator uses to remove heat from food.