ThermoLift, a Stony Brook company trying to develop an ultraefficient system to heat and cool homes, has closed on $2.75 million in funding from local investors through Topspin Fund and the Long Island Angel Network.

The company, based at Stony Brook University, will use the funding to continue developing its natural gas-powered thermal pump, which acts as a furnace, air conditioner and hot-water heater rolled into one.

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"A natural gas air conditioner is highly attractive to many markets globally. We believe ThermoLift is a transformational and new approach," said Steve Winick of Topspin, a Roslyn Heights venture capital firm that specializes in fledging biotech, life science and energy companies.

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The Long Island Angel Network, based in Hicksville, provides startup funding for local tech companies.

ThermoLift, founded in 2012, has raised a total of $5.7 million in startup funding. It has 10 full-time employees, at offices at Stony Brook's Advanced Energy Center and in Ann Arbor, Michigan.

The company's heating and cooling system is based on a German model developed in the 1990s. ThermoLift plans to use the latest round of funding to test its prototype at Oak Ridge National Laboratory in Tennessee.

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"Both Topspin and the LI Angels have been excellent financial and strategic partners for ThermoLift," ThermoLift chief executive Paul Schwartz said. "We are extremely happy with the most recent investment."