A heat pump works similarly to an air-conditioner except it can move air in two directions — into the home and out of the home — being a furnace and an air conditioner all in one. An air-source heat pump (also called an air-air heat pump) extracts heat from the air outside your home and pumps it inside through coils that contain refrigerant. Beside the coils, the pump unit has two fans, a compressor and the key to making the unit both a heater and an AC — a reversing valve. Very well-insulated homes, even in frigid New England, can be heated almost entirely with a heat pump due to advancements in this technology that allow air-source heat pumps to extract heat from the air to about 15 degrees Fahrenheit.
Besides the basic air-source heat pump, there is also a ground-source (geothermal) heat pump. Ground source heat pump systems extract heat from deep in the ground rather than from outside air. The advantage to air-source heat pumps is that they are far less expensive to install compared to ground source heat pumps, and they can do the same job.
Air-source heat pumps either connect to a whole-house duct system or are installed in an exterior wall to serve a particular room or house section. The latter are called ductless mini-split heat systems. The main advantages of mini splits are their small size and flexibility for zoning or heating and cooling individual rooms. If you have a particular room or house section that you want to make more comfortable, a mini-split may be the ideal solution.
I was visiting a professional office in Newburyport recently where it was cooler than normal inside. I noticed it was heated with electric baseboard, which is why the thermostat was set low — electric heat is expensive. This situation represented a perfect example of where a low-cost mini-split heat pump could be installed to cut the electric bill by about two thirds. Rebates from utilities provide additional incentives and help subsidize the installation of air-source heat pumps.
Now, let’s talk efficiency and savings. Heat pumps will lower your energy costs, both to heat and to cool your home. Heat pumps can deliver one-and-a-half to three times more heat energy than the electric energy it consumes to run. When purchasing a heat pump, look for a SEER (seasonal energy efficiency rating) of between 14 and 18. The SEER represents how much energy (measured in BTUs) is pumped outside when the pump is cooling your home divided by the electricity used (in watts) for cooling. Secondly, look for an HSFP (heating seasonal performance factor) of around 9. This represents the energy pumped indoors for heating divided by the energy used for heating, while also factoring in supplemental heating needs and the energy used to defrost the pump.
Air-source heat pumps compare favorably with traditional boilers and furnaces in terms of the cost to heat a home. For example, a gas-fired furnace costs about $18 per million BTUs at current prices for natural gas. An air-source heat pump costs between $12 and $15 per million BTUs to operate at current prices for electricity. Heating with oil, propane and conventional electric heat elements are far more expensive in the range of $45 to $60 per million BTUs. In terms of installation costs, air-source heat pumps systems average between $1,500 to $4,000.
When considering saving on your heating costs, especially if you have a particular room or section of your house that is difficult to keep comfortable, an air-source heat pump may be the solution.
Tim Gould is the director of Informed Energy Solutions in Amesbury. Contact him at 978-388-6349. On the web at www.InformedNRG.com.