Despite their name, heat pumps do a lot more than heating. They also provide air conditioning and humidity control. During the heating season, a heat pump moves heat from the cool outdoors into your home; then during the cooling season, it transfers heat from your house to the warm outdoors. Heat pumps move heat rather than generate it, so they can heat and cool for significantly less cost than other systems, such as furnaces and central air conditioners.
There are three main types of heat pumps—air source, split ductless, and geothermal. All heat pump systems should be installed by a professional heating and cooling technician who can determine the proper size and right product for your home and climate.
Air-source systems are the most commonly installed heat pumps. They have two parts: an indoor unit (air handler) and an outdoor unit (heat pump). A refrigerant, which circulates between the two units through tubing, absorbs and releases heat as it moves back and forth.
New air-source heat pumps can reduce your heating costs by about 50 percent over electric furnaces and baseboard heaters. They also dehumidify better than standard central air conditioners, so your home will be more comfortable in warmer, muggier months.
In the past, air-source heat pumps were more appropriate for warmer climates. But in recent years, the technology has improved, so they’re now viable for colder regions, such as the upper parts of the Northeast and Midwest. However, you will need an auxiliary heating system if temperatures in your area drop below 10 degrees F to 25 degrees F (depending on your system’s size).
Split-ductless heat pumps have two units: an outdoor compressor/condenser and one to four indoor air handlers. The quiet indoor units are installed high on a wall or on the ceiling, and are operated by a remote control. Also called mini splits, the systems circulate refrigerant through tubing that connects the indoor and outdoor units.
Split-ductless systems don’t require ductwork, so they are practical for single-room additions or for homes without ducts. Mini splits also avoid the energy losses associated with ductwork, which can account for more than 30 percent of a home’s energy consumption for space conditioning. Plus, they offer design flexibility (although some homeowners don’t like the look of the indoor units).
The cost of installing a split-ductless heat pump with multiple indoor units can be higher than other systems, but federal and other incentives can defray the initial installation cost.
Geothermal heat pumps (also called ground and water source) move heat through a series of pipes buried vertically or horizontally in loops outdoors. The pipes contain a water solution, which is warmed by the constant 50 to 60 degree F temperature of the ground, pond or well, and is circulated into and out of your house.
Geothermal heat pumps, which also control humidity, can reduce your home’s energy use by 25 percent to 50 percent when compared with a conventional heating and cooling system. Plus, they are quiet, long lasting (indoor units last about 25 years and loops about 50 years), require little maintenance and are effective in extreme climates.
However, geothermal is not practical for small lots and certain soil conditions, and installation is costly—$20,000 to $25,000 for a 2,500-square-foot home, or several times that of an air-source system. However, federal and local incentives can drop the initial cost considerably, and you are paid back in energy savings in five to 10 years.
Climate
New heat pumps work efficiently in many parts of the country, but especially in places without wide temperature swings and moderate heating and cooling needs. But if you live in an area with extremely cold temperatures, below 10 degrees F to 25 degrees F depending on system size, you will need an auxiliary heating system.
Energy Efficiency
The cooling efficiency for air-source and ductless-split systems is measured by SEER (Seasonal Energy Efficiency Ratio). The federal minimum standard is 13 SEER for new units for homes in the Northeast, Midwest, Mountain States and Pacific Northwest; for the rest of the country, the minimum is 14 SEER.
The heating efficiency of air-source and ductless-splits systems is measured by HSPF (Heating Seasonal Performance Factor). The minimum federal HSPF rating for all units is 7.7.
In warmer climates, a higher SEER is more important, but in colder climates, a higher HSPF is better. According to the American Council for an Energy-Efficient Economy, you should consider buying a heat pump that is at least 15 SEER and 8.5 HSPF. The most-efficient Energy Star-rated heat pumps are 18 to 27.5 SEER and 8.5 to 12.5 HSPF.
A geothermal heat pump’s cooling efficiency is rated by EER (Energy Efficiency Ratio) and its heating efficiency by COP (Coefficient of Performance). Based on type, the federal EER minimums are 17.1 to 21.1 and the COP minimums are 3.1 to 4.1.
Typically, the higher the rating, the higher the system’s cost. You can spend several thousand dollars more for a more efficient heat pump. But, depending on where you live, you could save $115 a year or more on your utility bill by replacing your older heating and cooling system with an Energy Star-rated product.
Sizing
Size is also important. If a heat pump is undersized or oversized, it won’t heat or cool effectively and will increase your energy bills. And your home may not feel comfortable. A unit that’s too big will cost more upfront, and will cycle on and off too many times, shortening its life.
Work with a heating and cooling professional, who should use an Air Conditioning Contractors of America (ACCA) Manual J calculation to determine the right size. The calculation takes into consideration your home’s foundation, wall thicknesses, insulation values, windows, air filtration and more.
Tax Credits and Rebates
If you installed an Energy Star-certified geothermal heat pump by Dec. 31, 2016, you are eligible for a 30-percent federal tax credit on the purchase. Check the websites of the Internal Revenue Service and the Department of Energy for more details.
Likewise, some states and utilities offer credits and rebates on geothermal systems, and smaller federal credits and utility rebates are available for other heat pumps, too. Visit the federally funded NC Clean Energy Technology Center's website for a state-by-state list of available incentives.
Other Considerations
Don't buy a new heat pump until you make the rest of your home is as energy efficient as possible, because that will allow you to buy a smaller, less expensive system.
A heat pump won’t work as well, or provide as much annual energy savings as it should, unless the rest of your home is efficient, too. So, before you buy a heat pump, consider:
• Adding insulation to your attic and walls.
• Adding weather stripping around doors and caulk around windows.
• Properly sealing the ductwork throughout your home.
• Properly insulating the ducts in crawlspaces and attics.
• Installing and setting programmable thermostats to automatically lower the temperature at night in the cooler months and raise it in the warmer months, and adjust the temperature while you are away. Programmable thermostats can save you 10 percent annually on your energy bills.
Noise Output
Fans and compressors can be noisy, so select an air-source heat pump with a sound rating of 7.6 bels or lower. Also, locate the outdoor unit away from windows and consider positioning it on a noise-absorbing base. In addition, protect the outdoor unit from high winds, which can cause defrosting problems. Placing a shrub or a fence upwind of the coils will help.
Demand-Defrost Control
Frost accumulation on the heat pump’s outdoor unit can impede energy efficiency and compromise indoor comfort. So, select a model with a demand-defrost control. This feature will minimize defrost cycles, making your system more energy and cost efficient.
Reverse Cycle Chiller
A heat pump with a reverse cycle chiller allows you to pair it with a wide variety of heating and cooling distribution systems, and it can help make your home more comfortable. The technology can also lower your winter electric bills, and is especially economical in all-electric homes.