By Merritt Carey
If you’ve heard of heat pumps before, you’ve likely heard of them in the context of geothermal heat pumps. There are two types of heat pumps, geothermal and air source. Air source heat pumps have long been used in warmer climates for cooling, but now, thanks to rapidly improving refrigerant technology, air source heat pumps offer a highly efficient heating option in colder climates as well. But what exactly is an air source heat pump and how does it work?
Unlike most heating systems, heat pumps don’t actually make heat, they extract heat from the outside air, warm it using refrigerant and deliver it indoors. While it may seem counter-intuitive, refrigerant has a very low boiling temperature allowing it to create heat even in below zero temperatures. In some circumstances heat pumps can be used as a sole heating source. However, in most cases, home owners will want a backup heating source as well.
Heat pumps offer considerable savings and convenience with relatively low upfront costs. For example, a heat pump can be purchased and installed for around $3,500, offering homeowners approximately a 3-to 4-year payback. This payback can often be accelerated with financial incentives. As with many green or renewable heating options, there may be federal and state incentives to defray installation and purchase costs. These programs, typically in the form of tax credits or rebates, change frequently (look for updated information on Efficiency Maine’s website). And because heat pumps create heat in a highly efficient manner, the cost of heat generated with an air source heat pump can be the equivalent of paying approximately $1.50/gallon today for oil.
A heat pump is typically mounted on an outside wall and has both an inside and outside unit. They are not connected to an air distribution system or radiators, but rather heat directly from the units in the same way a window air conditioning unit cools air. In Maine, sales of heat pumps have just about doubled in the past two years as their technology has rapidly improved.
Photo courtesy of Efficiency Maine
There are obvious advantages to heat pumps. They allow homeowners to cut heating costs considerably without a huge cash outlay and are more environmentally friendly than many other heating systems. Heat pumps don’t create any direct emissions and while they use electricity (for the fan and compressor), that can be sourced from renewable sources such as wind or solar power. As a result, for a homeowner dedicated to finding the greenest possible home heating solution, heat pumps offer considerable advantages. Currently, there are heat pumps which work down to -15 degrees Fahrenheit.
For new construction, or in open plan homes that are well insulated, it’s possible to have a heat pump as your only heat source. If you are interested in going this route, be sure to consult with a knowledgeable installer who can provide guidance around how to ensure your home will stay warm even on the coldest winter days.
If you’re interested in finding out more about heat pumps and whether they might provide a good solution for your home, Maine has excellent resources readily available. The Efficiency Maine website has considerable information as well as a searchable registered vendor database and a cost comparison calculator. The Efficiency Maine website also provides information about available rebates or other financial incentives.
IN A NUTSHELL:
Pros
- Excellent cost savings with minimal upfront investment ($3,500)
- Easy to install
- Environmentally friendly
- Quiet
- Small, aesthetically pleasing
- Acts as an air heater, air coolant, dehumidifier and filter
Cons:
- Need to keep back up heating source (air source pumps will shut down on days when the temperature reaches -15 degrees)
- Loses efficiency in colder temperatures
