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Illustration courtesy of Collaborative Efficiency
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Illustration courtesy of Collaborative Efficiency
Q. We’ll need to replace our furnace soon and wonder if a heat pump would help us save some money. Do you have any suggestions?
A. For most of us, heating and cooling account for the largest part of our household energy use.
An electric air-source heat pump can be a good alternative to a furnace system that runs on propane or fuel oil.
Heat pumps not only reduce energy costs, they can also eliminate the risk of carbon-monoxide poisoning and problems that can occur with on-site storage of propane or heating oil. A heat pump is also a cost-effective alternative to the electric-resistance heat used in electric furnaces and in baseboard and wall units.
How heat pumps work
In the summer, an air-source heat pump acts as an air conditioner that draws heat from your home’s interior and transfers it outside. In the winter, the direction is reversed, so heat is pulled from the outside air and moved into your home.
The heat pump has two major components: the condenser (also called the compressor), which circulates refrigerant through the system, and an air handler, which distributes the conditioned air, usually through a duct system. Most heat pumps are split systems, with the condenser located outside and the air handler inside. A packaged system contains both components in one unit placed outside your home.
In winter, heat pumps must work harder as the outdoor temperature drops, because there is less heat to extract from the outside air. At some point, the heat pump switches to electric-resistance mode, similar to how a toaster creates heat, to maintain the home’s temperature at the thermostat setting. This is less efficient and more expensive. For greater efficiency during cold weather, consider a dual-fuel system, which uses a heat pump along with a gas or propane furnace.
If your old furnace has an air conditioner attached, replacing both the heating and cooling system with the all-in-one solution of a heat pump might save money. If you are cooling with window units or have an older central-air conditioner, moving to an air-source heat pump could reduce your summer energy bills.
Selecting and installing
The abbreviations SEER and HSPF can help you compare the efficiency of different heat pumps. SEER (Seasonal Energy Efficiency Ratio) measures cooling efficiency for airsource heat pumps. HSPF (Heating Seasonal Performance Factor) measures heating efficiency. The minimum standards for heat pumps are SEER 14 and HSPF 8.2. Look for an Energy Star label, which indicates the unit is at least 15 SEER and 8.5 HSPF. Visit energystar.gov for more about equipment, proper installation, qualified contractors, and information and calculators to help you predict energy savings.
How much can a heat pump reduce your energy costs? This depends on the size and efficiency of your home, local energy prices and local climate. Some data have shown the cost of heating in South Carolina, using a new heat pump and national average fuel costs, to be less than half the cost of heating with a typical propane furnace or an electric-resistance system.
Energy auditors can predict energy savings with greater precision, advise about brands and proper size for the unit, and suggest ways to improve comfort or reduce energy use, such as duct sealing or insulating the building envelope. Visit resnet.us for information about energy audits.
Send questions to Energy Q&A, South Carolina Living, 808 Knox Abbott Drive, Cayce, SC 29033, email energyqa@scliving.coop or fax (803) 739-3041.
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