How to Vent a High-Efficiency Furnace

All furnaces need proper ventilation to expel carbon monoxide and other harmful substances that are produced as natural byproducts of furnace combustion.
But furnace ventilation also needs to be designed for the specific ventilation needs of the type of the furnace you are using. Newer, higher-efficiency furnaces, for example, require different kinds of ventilation than do than their older, less efficient counterparts.

Step 1

Install a masonry chimney, metal double-wall chimney or another type of manufactured chimney in your home if there is not one already. If one is already installed in your home, have its outer seal inspected for air leaks and repair any that are discovered.

Step 2

Replace single-walled venting components with double-walled venting components. New, high-efficiency furnaces produce combustion byproducts at a much lower temperature than older models; these cooler byproducts can create hazardous condensation in furnace venting. Using double-walled ventilation helps mitigate the temperature differences between the inside and outside of the vents that create moisture.

Step 3

Install fireclay, masonry liner or a retrofitted metal flue liner on the inside of your furnace's ventilation chimney. This final step to properly venting a high-efficiency furnace ensures that your chimney is lined with a material that can resist the natural corrosion that will occur from exposure to your furnace's combustion byproducts.

Things You Will Need

  • Doulbe-walled vent pipe
  • Chimney liner (fireclay, masonry liner, retrofitted metal flue liner or other type)

About the Author

Eoghan McCloskey is a technical support representative and part-time musician who holds Bachelor of Arts degrees in English and political science from Texas State University. While at Texas State, McCloskey worked as a writing tutor at the Texas State Writing Center, proofreading and editing everything from freshman book reports to graduate theses.