Most people in New England could cut their heating bills in half, when the time comes to choose a new heating system.
Over the last couple years, we have seen more and more mention of air-source heat pumps in the news. Last year, we started to see some European countries talking about laws mandating the use of heat pumps in all new residential construction. This year, Green Mountain Power in Vermont offered to rent 200 heat pumps to customers, and 600 asked to get them.
Despite the presence in the news, most people seem to draw a blank when a heat pump is mentioned. Of those who think they know about them, some seem to think only of expensive, ground source systems, so-called geothermal heat pumps that are far beyond the economic reach of ordinary people.
An air-source heat pump is actually rather easy for most of us to understand, because most of us actually use them from time to time. It happens that an ordinary air conditioner is a heat pump of sorts. While it runs, an air conditioner extracts heat from a cool room and pumps it outside. While the science behind this seems obscure to many people, nearly everyone understands that it does work.
An air-source heat pump differs from an ordinary air conditioner in a couple of ways. First of all, it extracts heat from cold outside air and pumps it into a warm interior space, the opposite direction of the air conditioner’s heat flow. We should note that most air-source heat pumps can work either way and function as air conditioners in the summer.
Second, air-source heat pumps are typically far more efficient than air conditioners. And this is where the business of cutting your heating bill in half comes in. Heat pumps do not create heat, the way electric resistance heaters do. They move heat. It happens that moving heat requires far less effort than creating it. In fact, an air-source heat pump may use only 40% or less of the electricity that a standard electric heater does to heat a space.
Since the resistance heater converts all of the electricity it uses to heat, it is rated at 100% efficient. Since the air-source heat pump can move 2.5 times the heat that the resistance heater creates with the same amount of power, the heat pump is considered to be 250% efficient.
The best test of efficiency might be how well the heat pump performs in terms of costs. In New England, heat pumps turn out to be among the lowest cost heating options. Air source units are just a fraction more expensive to run than ground source, or geothermal, heat pumps, but they cost far less to buy and install. They can also be less costly to install than new fossil fuel heating systems. In fact, for many people they are no more expensive to run than conventional woodstoves.
Air source heat pumps are far less expensive than oil, propane, or conventional electric heaters. Another piece of good news is that they do not pollute, and can be powered by renewable electrical sources. In fact, they can, and are, being run off-grid.
One person who has looked into heat pumps and decided to install them in his house is Tony Klein, Vermont State Representative for East Montpelier and Middlesex, Vermont. Since he is the Chairman of the House Natural Resources and Energy Committee and the Joint House and Senate Energy Oversight Committee, we imagine he did his homework on the subject.
Tony says, “I am convinced that heat pumps will substantially lower my cost of heating this winter.” Noting side benefits of having air-source heat pumps, he adds, “Mainly we had them installed to provide air conditioning in the summer and to solve a downstairs humidity problem.”
Tony chose Cacicio Heating in East Montpelier to install Mitsubishi “Mr. Slim” units for the lower floor of his ranch house and two upstairs rooms. He said the cost of the units was about $8,000. Noting that there were no incentives to apply to their purchase, he added, “If I were a GMP customer there would have been incentives.”
He expects to cut his propane heat cost by 70% and electricity bill to increase by 20-25%. These figures would produce a net savings of over $1,000 per year.
“I couldn’t begin to tell you the science behind it,” Tony says. But he adds, “So far the house is way more comfortable.”