Geothermal Heat Pump: How It Works

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Geothermal Heat Pump: How It Works by Max Alexander

Loves Heating & Air
This Old House Magazine Summer 2008

Even with this significant front-end investment, geo­thermal heat pumps systems are so energy-stingy that the payback period is remarkably brief. A study by the Air Force Institute of Technology calculated that it takes on average just seven to eight years to recoup costs. Your actual break-even point depends on local utility rates, excavation/drilling costs, how well your house is insulated, the efficiency of the model you choose, and what incentives your state or utilities provide. A good installer who’s knowledgeable about heating and cooling as well as your local geology will be able to make those calculations for you.

The current federal incentive is limited to the standard $300 tax credit for Energy Star HVAC installations. (Canadians retrofitting an existing home with geothermal qualify for a $3,500 federal grant.) Some forward-thinking utilities have offered low-interest loans to homeowners willing to adopt the technology. “It’s a win-win arrangement,” says Steve Rosenstock, energy solutions manager at the Edison Electric Institute, an association of utilities. “The utilities reduce peak demand for heating and cooling as their customers dramatically lower their electric bills.” And because the plastic ground loops should last 50 years or more, the payoff for homeowners, and for the environment, can last for generations….

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