Wow, Awesome – Rebates on Heat Pumps in Maine!

 Wait. What’s a heat pump?

            Many people are confused about heat pumps: how they work, what they do. Don’t feel bad if you are confused, because very few people seem to understand them at all. Still, they are worth understanding, because they can make a big difference in your heating bill – and in your “carbon footprint.” And there are big rebates for installing them in Maine right now.

    There are ground source heat pumps and air source heat pumps. There are even water source heat pumps for a home adjacent to a pond or lake. The basic mechanism at work is that we take heat out of the source, be it air, ground, or water, and put it into your house with the heat pump.

      Most household heat pumps in Maine are air-source heat pumps, also known as “mini-splits.” The cost of air source heat pumps is quite a bit less than ground source heat pumps, so they pay for themselves much faster and they require a lot less capital outlay.

    Incidentally, people often refer to ground source heat pumps as “geothermal,” conjuring images of hot springs, geysers, molten layers in the earth, and other very hot things.  Actually the temperature of the “source” of ground source heat is about 40 – 45 degrees Fahrenheit.

The thing that probably confuses people is that you can extract heat from things like 45 degree ground and 25 degree air.  It is not, as they say, “intuitive!” Nevertheless, you can extract heat from a substance of pretty much any temperature by using a little physics and engineering.

Heat pumps work essentially like refrigerators, using a refrigerant to take heat out of somewhere and put it somewhere else.  You know how the coils at the back of the refrigerator are hot – it is because the refrigerant in the coils cools the inside of the fridge by extracting the heat from it.  Similarly, a heat pump cools its source (the ground, the outside air) by extracting heat, which it then pumps into your house. The process is reversible, and so in the summer you can use the heat pump for air conditioning.

Now, it is true that with outside temperatures like those we have in Maine, it is not possible to provide all of our heat with air source heat pumps.  Heat pumps combine very well with other automatic heating systems – automatic stoves, furnaces, and boilers, whether oil or gas or pellet. When the temperatures outside are above a certain level, another automatic source of heat can supplement the heat pump as needed.

Meanwhile heat pumps can easily provide for ⅔ of your heating needs, and so thereby significantly lower your need for fuels.  Heat pumps do use electricity, which is generated from various sources including fossil fuels, but the magic is in the numbers.

One gallon of fuel oil contains about 140,000 Btu (British thermal units) of energy.  When you burn it to heat your house it delivers about 125,000 Btu of heat if you have a high efficiency furnace or boiler.

            Electricity, of course, also contains energy.  The 125,000 Btu you are getting from your furnace is equal to 37 kWh (kilowatt-hours) of electricity. But using electricity to run a heat pump, 37kWh can deliver as much heat as between 3 to 5 gallons of fuel oil, due to the heat you are getting from the air or ground.  In other words you can get a gallon’s worth of heat for less than 12 kWh of electricity. Comparing prices, that gallon of oil is around $2.60 right now while those 12kWh will cost you less than $1.80.

Incidentally you also reduce your carbon footprint significantly with the heat pump.  Burning a gallon of fuel oil produces about 20 pounds of CO2, while generating those 12 kWh of electricity produces about 5lbs of CO2. That’s a 75% reduction!!

The installation cost of heat pumps will vary depending on the construction of your home and the size of the space to be heated.  A typical installation is around $2500 for an 18,000 Btu-per-hour unit. Right now, Maine has a program that will provide rebates of $1,000  for installing your first high-efficiency heat pump, and $500 for the second one (https://www.efficiencymaine.com/at-home/ductless-heat-pumps/) – so it is a good time to act if you are considering it. With this rebate program your energy savings will generally pay for the system in 3 to 5 years.

Efficiency Maine is running the rebate program. You can call them at 866-376-2463 to learn more about the program, which heat pumps qualify, and how to find a contractor.

We hope this article has helped you feel more up-to-speed on heat pumps, and that you will feel more able to evaluate how they can help with your heating (and cooling) future!

Paul Stancioff, PhD., is a professor of Physics at the University of Maine Farmington, who studies energy economics on the side.  He can be reached at pauls@maine.edu. Cynthia Stancioff, MA, Public Administration, is an amateur naturalist and writer.