How a High-Efficiency Furnace Works

All forced-air furnaces burn fuel to heat air, then a blower fan distributes warm air through ducts to your home.

High-efficiency furnaces:

How furnace works
  • Have additional heat exchange surfaces that extract more heat. As the exhaust gases cool, they condense or turn to water. High-efficiency furnaces are known as condensing furnaces. 
  • Require a floor drain to dispose of the water formed during the combustion process.
  • Do not require a chimney since combustion products are vented through PVC or ABS plastic pipe out the side of the house.
  • High-efficiency furnaces have an Annual Fuel Utilization Efficiency (AFUE) rate of 90 to 98 per cent.

More information

Learn about furnace features and energy-efficient options.