High efficiency furnaces produce and deliver heat using less energy than the conventional model you probably have in your basement right now. A furnace uses energy to produce and deliver heat. Most homes are heated with either furnaces or boilers. Furnaces heat air and distribute the heated air through the house using ducts. Boilers heat water, yielding either hot water or steam for heating. Because steam boilers operate at a higher temperature than hot water boilers, they are inherently less e