Furnace System GuideSystems index
Furnace Types: Gas, Electric, Oil, and High-Efficiency
Compare furnace system families: gas furnaces, electric furnaces, oil furnaces, and high-efficiency condensing furnaces, with how each heats, vents, and fits your home.
System type
Gas Furnaces
Natural gas and propane furnaces: how they heat, AFUE efficiency tiers, venting, and what they fit.
System typeHigh-Efficiency Condensing Furnaces
90 to 98 percent AFUE condensing furnaces: secondary heat exchanger, condensate, and when the payback works.
System typeElectric Furnaces
Electric resistance furnaces: how they heat, where they fit, and operating cost realities.
System typeOil Furnaces
Heating oil furnaces for homes without gas: efficiency, tanks, and maintenance.