A heat pump is a wonderful option for your home comfort system. If it’s time to start considering a replacement for your present heat pump or you’re thinking of installing one for the first time, there are numerous elements to consider. First, it is important to install a heat pump that compliments the extent of your home and that it is also well-matched with the style of furnace or air-system you already own in home.
How does a Heat Pump Work?
Heat pumps are just two-way air conditioners. During the summer, an air conditioner works by moving heat from the relatively cool indoors to the relatively warm outside. In winter, the heat pump reverses this trick, scavenging heat from the cold outdoors with the help of an electrical system, and discharging that heat inside the house. Almost all heat pumps use forced warm-air delivery systems to move heated air throughout the house.
A ground-source heat pump heats and cools in any climate by exchanging heat with the ground, which has a more constant temperature.
There are two relatively common types of heat pumps. Air-source heat pumps use the outside air as the heat source in winter and heat sink in summer. Ground-source (also called geothermal, GeoExchange, or GX) heat pumps get their heat from underground, where temperatures are more constant year-round. Air-source heat pumps are far more common than ground-source heat pumps because they are cheaper and easier to install. Ground-source heat pumps, however, are much more efficient, and are frequently chosen by consumers who plan to remain in the same house for a long time, or have a strong desire to live more sustainably. How to determine whether a heat pump makes sense in your climate is discussed further under “Fuel Options.”
Whereas an air-source heat pump is installed much like a central air conditioner, ground-source heat pumps require that a “loop” be buried in the ground, usually in long, shallow (3–6′ deep) trenches or in one or more vertical boreholes. The particular method used will depend on the experience of the installer, the size of your lot, the subsoil, and the landscape. Alternatively, some systems draw in groundwater and pass it through the heat exchanger instead of using a refrigerant. The groundwater is then returned to the aquifer.
Because electricity in a heat pump is used to move heat rather than to generate it, the heat pump can deliver more energy than it consumes. The ratio of delivered heating energy to consumed energy is called the coefficient of performance, or COP, with typical values ranging from 1.5 to 3.5. This is a “steady-state” measure and not directly comparable to the heating season performance factor (HSPF), a seasonal measure mandated for rating the heating efficiency of air-source heat pumps. Converting between the measures is not straightforward, but ground-source units are generally more efficient than air-source heat pumps.
Most Fuel Efficient Heat Pumps
Currently the only ENERGY STAR rated heat pumps are geothermal.
These include:
American Standard Series, Bosch Greensource Series, Bryant Series, Carrier Series, Climate Master Series, EarthLinked Prime Series, GeoSmart Series, GeoStar Series, Hydro-Temp Star Series, Modine Series, Trane Series, Waterfurnace Series, and York Series.
Source: EnergyStar.gov