What the Annual Fuel Utilization Efficiency Rating Means

As you prepare for what may be your highest heating bill of the year, it’s good to understand what the Fuel Utilization Efficiency Rating means for your heating system.

The AFUE rating is a percentage ratio of how much fuel your furnace uses in ratio to how much heat it produces. If your furnace has a 75% AFUE rating it means that 75% of the fuel it takes in produces heat, and 25% of the fuel is wasted. Therefore, the higher the percentage AFUE rating, the more efficient your furnace is.