Up here in Maine, the words "heat" and "pump," when strung together, elicit something between a wince and a guffaw. Central air conditioning is a novelty up here, used primarily in commercial establishments–and sparsely even in those. For heating, the technology is utterly useless. Or at least it was until now.

William Gloede Founded in 2005, Bangor, Maine-based Hallowell International has developed an air-source heat pump HVAC system called the Acadia that not only works in temperatures well below zero degrees Fahrenheit but also rivals geothermal systems in efficiency at a fraction of the installed cost. It runs–as all heat pumps do–on electricity, which, given the recent rapid rise in the cost of fossil fuels, is the most cost-effective source of energy this side of the sun and the wind.

Those in the know are probably scoffing right about now. Duane Hallowell, president and CEO, is accustomed to the scoffing.

"What we are doing is known to be impossible," says Hallowell with a glint in his eye. He has a pointer in his hand and is whacking away at a graphic on the wall that depicts the heating capacities of an Acadia system at various outside temperatures. The bars over on the right of the chart say minus 30 degrees Fahrenheit.

According to Boyle's Law, if temperature remains constant, the volume of a given mass of gas is inversely proportionate to the absolute pressure. Therefore, if one raises the pressure of the gas via a compressor, and the volume remains constant, the temperature must go up.

FREEZE FRAME: CEO Duane Hallowell (left) and VP/sales and marketing Chip Curtis at Hallowell International stand in a psychometric chamber in which the temperature has been reduced to two below zero by the Acadia system, which has transferred the heat into an adjacent lab. Photo: Bill Gloede This is how a conventional heat pump–or your average air conditioner–works, with the exception that the refrigerant changes from a liquid to a gas under pressure. Every heat pump or A/C unit has a high-pressure side that disperses heat though a condenser and a low-pressure side that absorbs heat through an evaporator.

Unlike conventional heat pumps, the Acadia adds a compressor to the cycle's low-pressure side. This involves much more than just installing a second compressor; there are eight separate patents that explain how it is accomplished. "We're well protected," quips Hallowell.

"Today's air-source heat pump is designed primarily as an air conditioner with a secondary function for heat," he explains. The Acadia started as a heating unit. It employs two stages of compression, an additional booster compressor, variable-speed electronically commutated motor (ECM) technology on blowers, and programmable thermostats that combined deliver four stages of heat and two stages of A/C. The result is an extremely comfortable heat from a forced-air system, better humidity control, and an 80 percent reduction in the time needed to reverse cycles to defrost the system–a common problem with conventional heat pumps.

United Communities, which is currently privatizing the housing facilities at McGuire Air Force Base in southern New Jersey, is installing 2,400 Acadias. The man who put United together with Hallowell, HVAC contractor and owner of Beta American Services Pete Monahan thinks the Acadia "is the best air system on the market, and there are a lot of good air systems out there."

"We've got about 22 of the systems in," he adds. "We've been down to 10 and 12 degrees, and we had no problem at all. We haven't had to use the resistance heat [the fourth stage of heating, meant for temperatures below 0 degrees Fahrenheit]."

The Seasonal Energy Efficiency Rating for the Acadia is 16.5; the Heating Seasonal Performance Factor is 9.7. Its savings over fossil fuels is dependent on the going price of those fuels versus the electricity rate, but savings can be more than 50 percent.

An Acadia system runs between $8,000 and $14,000, installed. Hallowell promises more technological advances in the near future and has signed Parker Hannifin as a strategic partner. The company's Web site is www.gotohallowell.com. Cute.