Heating
Oil or gas furnaces work by burning oil or gas in a sealed chamber. The blower circulates air around the outside of the chamber, where the air absorbs heat before it is circulated back into the home through the ducts. The byproducts of burning oil and gas are combustion gases, some of which are lethal. Those gases are vented to the outdoors via a metal or plastic flue pipe. Newer systems include a second pipe which gathers air from outside the home for the fire in the combustion chamber. Older systems pulled conditioned air from inside the home for this purpose. As that air was used in combustion, cold air from outside the home was pulled through cracks in the building’s shell, making the home feel drafty and cold, and lowering efficiency. “Newer furnaces, by bringing in outside air for combustion, don’t pull replacement air through a home’s gaps and cracks,” says Moody, “That means they’re more efficient, operate more safely, and make a home more comfortable than older furnaces.”
Electric furnaces use electric strip elements which convert electricity to heat, much like in a toaster or hair-dryer. Air from the house absorbs heat as it passes by the red-hot heating element. That air is then distributed to rooms in the home via the ducts. While quite simple, reliable, and safe, resistance heating is generally considered a less efficient and more expensive way to heat a home.
Heat pumps, either air-source or geothermal, are the most efficient way to heat and cool with electricity. Air-source heat pumps are the most common, and use a refrigerant or chemical to absorb heat from the air outside the home, concentrate it, and use the concentrated heat to warm the home. While quite efficient, air-source heat pumps can lose efficiency as the outside air get very cold. Geothermal uses heat energy from the earth for the same purpose. Since geothermal systems use heat from the ground, it’s immune to the very cold weather inefficiency that air-source heat pumps experience.
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