By Megan McKoy-Noe
Heat pump systems move heat into residences during winter and out of them in summer, trimming overall home heating and cooling costs by as much as 40 percent, according to the U.S. Department of Energy (DOE).
Different heat pumps succeed in specific regions. Air-source heat pumps work well in the Southeast, where temperatures rarely drop below freezing. In more northerly climates geothermal heat pumps shine because their heat source remains shielded—the top 10 feet of earth consistently measures between 50 to 60 degrees Fahrenheit.
A heat pump system can deliver value to your home if the model used matches your region and if it’s installed properly. Here’s a guide to three different types of heat pumps.
Outside temperatures may vary, but the earth’s temperature remains steady year-round and can be harnessed to make homes comfortable. According to DOE, geothermal heat pumps offer energy savings between 30 percent and 60 percent annually when compared to conventional baseboard or radiant heating systems, and are typically the most efficient heat pump option.
Geothermal heat pumps move a liquid or water through pipes buried in the ground, then into a home. Also called ground-source heat pumps, there are two types of units: a groundwater (open-loop) system uses well or pond water, while an earth-coupled (closed-loop) model uses a water and antifreeze solution. Systems can be installed horizontally or vertically, depending on available space.
Geothermal efficiency depends on climate, soil and water conditions, and landscaping. For example, soil that transfers heat easily requires less piping. Rocky terrain may require a vertical loop system instead of a more economical horizontal loop system.
When buying a geothermal system, compare two elements: coefficient of performance (COP) for heating, and the energy efficiency ratio (EER) for cooling. ENERGY STAR-qualified models must provide a rating of at least 2.8 COP and 13 EER.
Air-source heat pumps use a system of coils to evaporate a refrigerant and, with it, draw heat away from a home, cooling the air. In winter the magic reverses with the flip of a valve, and your home heats.
The system delivers up to three times more heat energy than electricity consumed, but is not perfect. Air-source heat pumps often do not fare well in regions with sub-zero temperatures. A back-up system of electric resistance coils kicks-in when air temperatures dips below 40 degrees Fahrenheit, but this method of heating—similar to a toaster—isn’t energy efficient, costing more to operate than traditional heating systems.
When shopping for an air-source heat pump, compare the seasonal energy efficiency rating (SEER) for cooling prowess, and heating seasonal performance factor (HSPF) for compressor and heating element strength.ENERGY STAR models guarantee a SEER of 12 or more and a HSPF of 7 or more.
One option to avoid duct leakage, which can waste 15-20 percent of your heating and cooling energy, is to bypass ducts with a ductless version of an air-source heat pump (DHP), also called a “mini-split” heat pump.
Small and versatile, ductless heat pumps have two main parts: an outdoor compressor/condenser and one or more indoor air-handling units. These components are linked by a cable (refrigerant line). Many systems offer up to four indoor units to condition different rooms, and some systems come with wireless remotes or wall-mounted control units.
According to CRN, these devices use an estimated 50 percent to 60 percent less energy than traditional forms of heating. DHPs are ideal for room additions where duct work may not be possible, or for homes with “non-ducted” air conditioning (i.e. window units). Indoor models can be mounted in the ceiling, hung on the wall, or placed on the floor.
DHPs are costly—30 percent more expensive than traditional central air systems (not including ductwork). Installation can also be tricky—if a system is too big for the space, energy will be wasted and the correct temperature may not be reached.
Saving on Systems
Although heat pumps are more expensive than traditional air conditioning, rebates and tax credits can help cut the cost. A federal tax credit equal to 30 percent of the cost for materials and installation, with no limit on total project expenses, applies to geothermal heat pumps through Dec. 31, 2016. A list of requirements can be found atwww.energystar.gov/taxcredits. To find incentives in our state, check the Database of State Incentives for Renewables and Efficiency at .
Since heat pump success depends on region, contact your local contractor to find out which type of system might work for you.