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
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.
Choosing a Heat Pump
Reducing the Energy Cost of Your Heat Pump