For example, a gas furnace must have at least a 95% efficiency rating to qualify for the credit.

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Nucor has a number of growth initiatives, including new natural-gas furnace operations, strategic acquisitions and international joint ventures.

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And with all that money saved by the superefficient gas furnace in your basement, you fly to Aspen for a weekend in the snow.

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But when buying a furnace, make sure you buy one that uses liquefied natural gas, not propane, whose price is based on the price of oil, Davis said.

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But this portion could grow, given the hassles of making hydrogen:It requires a six-story furnace, called a steam-methane reformer, where natural gas combines with steam and nickel at 1, 600 degrees Fahrenheit to unleash hydrogen gas.

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