Understanding AFUE Will Help You Choose the Right Furnace ReplacementWinter’s on the way, so it’s time to prepare your Los Angeles home for the upcoming cool season. Energy efficiency and low operating costs are important factors when replacing a furnace, so discuss your options with your HVAC professional. Here are a few important points to consider before buying a furnace.

  • The annual fuel utilization efficiency (AFUE) of a furnace is the yearly ratio of the furnace’s heat output compared to the total amount of fuel consumed.
  • The Federal Trade Commission requires all furnaces to display their AFUE in order to compare heating efficiencies.

For example, an AFUE rating of 90 percent means that 90 percent of the fuel’s energy becomes heat and the other 10 percent escapes up the chimney and elsewhere. This does not include heat loss via ductwork or piping (which can reach 35 percent), especially if the ductwork is located in the attic, garage or in an unprotected crawl space under the home.

Unlike gas- or oil-fired furnaces, an electric furnace has no heat loss through a chimney, resulting in an average AFUE rating of between 95 percent and 100 percent. Electric units reflecting lower values are usually outdoor installations that lose heat through the metal casing. Electric units can have higher operating costs (dependent on local utility rates).

All Energy Star-labeled furnaces have an AFUE of 90 percent or higher. They not only use energy more efficiently, they contain sealed combustion chambers, posing fewer safety issues related to carbon monoxide emissions or flame rollout (accidental combustion outside the unit).

As of May 1, 2013, the minimum AFUE requirements for indoor (non-weatherized) furnaces are as follows:

  • Gas furnaces (not including mobile home furnaces) – 78 percent

As of Nov. 15, 2015, all non-weatherized gas-fired furnaces will have to have an AFUE of 80 percent.

For more information on AFUE ratings and furnace options, please contact us at Around the Clock Air Conditioning and Heating. We’ve provided expert HVAC service to the greater Los Angeles area since 1967.

Our goal is to help educate our customers in Los Angeles, North Hollywood and surrounding areas about energy and home comfort issues (specific to HVAC systems). For more information about furnace replacements and other HVAC topics, downloadour free Home Comfort Resource guide.

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