Using a Heat Pump
For climates with moderate heating and cooling needs, heat pumps offer an energy-efficient alternative to furnaces and air conditioners.

Like your refrigerator, heat pumps use electricity to move heat from a cool space into a warm place (heat pumps powered by natural gas are also commercially available now). During the heating season, heat pumps move heat from the cool outdoors into your warm house; during the cooling season, heat pumps move heat from your cool house into the warm outdoors.

Because they move heat rather than generating heat, heat pumps can provide up to 4 times the amount of energy they consume. If you heat with electricity, a heat pump can trim the amount of electricity you use for heating by as much as 30% to 40%. High-efficiency heat pumps also dehumidify better than standard central air conditioners, resulting in less energy usage and more cooling comfort in summer months.

If your home lacks a ductwork system, you would need to add one to convert to a heat pump system. Even if your house has ducts, you may need to modify them, as heat pump systems generally require larger duct sizes than other central heating systems. For proper heat pump operation, air flow should be 50 to 60 liters per second per kilowatt-hour or 400 to 500 cubic foot per minute per ton of cooling capacity.

The "conventional" model of heat pump is the air-source heat pump, which transfers heat between your house and the outside air. Although air-source heat pumps can be used in nearly all parts of the United States, they do not perform well over extended periods of sub-freezing temperatures. In regions with sub-freezing winter temperatures, it may not be cost effective to meet all your heating needs with an air-source heat pump.

Higher efficiencies are achieved with ground-source (or geothermal) heat pumps, which transfer heat between your house and the ground. Although they cost more to install, geothermal heat pumps have low operating costs because they take advantage of relatively constant ground temperatures. However, the installation depends on the size of your lot, the subsoil and landscape. If your house is located near a body of water, such as a pond or lake, water-source heat pumps offer similar advantages. Ground-source or water-source heat pumps can be used in more extreme climatic conditions than air-source heat pumps, and customer satisfaction with the systems is very high.

See Also:
Choosing a Heat Pump
Tips for Reducing the Energy Cost of Your Heat Pump