A -- A geothermal heat pump is probably the most efficient heating and air-conditioning system available for any home today. In the heating mode, the heat blowing out of the registers is often warmer than with a standard air-to-air heat pump, so comfort during the winter is better.
Throughout its life, installing a geothermal heat pump usually makes economic sense for the average home, but your electric co-op can do a payback analysis for you. If your house is extremely energy efficient and already has low utility bills, even cutting them in half with a geothermal heat pump may not justify its higher cost.
A geothermal heat pump both heats and cools your home like a common air-type heat pump, but that is where the similarities end. In the heating mode, a geothermal heat pump pulls free heat from a ground loop, well water, lake water, etc., for super-high efficiencies.
During the summer, the energy savings can be as much as 60 percent. Some geothermal models have efficiencies as high as a seasonal energy efficiency rating (SEER) of 22, compared to an old central air conditioner at about 8. The dehumidification factor is also often better for improved indoor air quality, less allergy problems, and better comfort.
When operating in the air-conditioning mode, most geothermal heat pumps offer the option of using a desuperheater device. This device takes the waste heat from your house that is normally exhausted outdoors and diverts it to your water heater for free hot water during the summer.
Geothermal heat pumps are energy efficient because they use the earth as the source of heat during the winter, and during the summer they exhaust indoor heat to the earth. Since the ground temperature several feet below the surface stays relatively constant year-round, a geothermal heat pump uses less electricity to heat and cool your house.
During the winter, even though it feels cold outdoors when it is 30 degrees, there is still heat energy in the air that a standard heat pump can "pump" into your house. At the same time, the ground temperature may be 55 degrees. It makes intuitive sense that it is easier to pull heat from the ground at 55 degrees than from the air at 30 degrees. The colder it gets outdoors, the greater the benefit of a geothermal heat pump becomes.
To install a typical ground-loop system, a series of small pipes is placed in deep narrow trenches dug in your yard with a backhoe. Drilling deep vertical holes can also be used. The pipes are connected to a heat exchanger inside the heat pump. An antifreeze solution runs through the pipes to capture heat during the winter or exhaust heat during the summer.
Another efficient design (called DX) does not use an antifreeze solution in pipes or a heat exchanger. Instead, thin copper tubing is placed in the ground and the actual refrigerant (freon or R410A) runs directly through it. This requires less overall ground-loop length and is ideal for smaller yards. The inefficiencies of using an extra heat exchanger are also eliminated.
For ultimate comfort and efficiency, select a two-stage model with a variable-speed blower. This allows it to constantly fine-tune the heating and cooling (and electricity usage) to the varying needs throughout the day.

Write for Utility Bills Update No. 644 for a buyer's guide to geothermal heat pumps. Include $3.00, a business-size SASE, and Update number. Mail requests and questions to James Dulley, Kentucky Living, P. O. Box 54987, Cincinnati, OH 45254. Go to www.dulley.com to instantly download.