In my research for the new TV series This New House (premiering at 8pm, July 29, on the DIY Network), I came across a heat source you might want to check out.
Heat pumps are tried-and-true machines that cool and heat buildings across the southern tier of the U.S. They use refrigerant to move heat from inside to outside, or vice versa. Like an air-conditioner, they take heat out of houses and dump it outside in the summer; in the winter, the process gets reversed, capturing latent heat in air down to about 37 F, concentrating it by compressing the refrigerant, and sending the heat inside. But below 37 F, they rapidly lose effectiveness, working constantly to try to keep up with heat demand. This is why they’re less common or economical up north, where they require back up systems that heat (expensively) with electricity.
There’s a company in the heart of the frost belt—Bangor, Maine—that’s cracked the code for heat pumps for cold country. By adding a secondary booster compressor, which basically turbo-charges the process, the Hallowell Acadia heat pump (http://www.gotohallowell.com/Acadia™-Products/) is able to draw heat from air as cold as -30 F. As company founder Duane Hallowell puts it, “It’s a heat pump on steroids.”
The heat-pump process is based on the simple fact that heat goes to cold: whenever something is colder than the surrounding air, the heat in that air transfers to it, as the system tries to equalize. By making the outside coil of the heat pump even colder than the air, the Acadia is able to capture latent heat in frigid conditions. Concentrate that heat and transfer it inside and, voila, you’re heating a northern house using the outside air. And it’s all done with electricity, freeing the user from the vicissitudes of the oil and gas markets.
About 4,000 Acadia heat pumps have been sold since the company opened in October of 2006. They cost about $10,000 installed—that’s compared to $30,000 for a geothermal system, which uses the ground as a heat source. The machines are eligible for tax and utility rebates up to $4000 and provide between 25 and 55% cost savings over natural gas and oil, depending on electricity costs in your area.