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The efficiency of a gas (natural or propane) or oil furnace is measured by the Annual Fuel Utilization Efficiency (AFUE), which describes the heat produced from the energy used. This rating takes into consideration losses from pilot lights, start-up, and stopping. For example, a furnace with an AFUE rating of 80 converts 80% of the fuel it burns into usable heat. New furnaces usually rate in the mid-70s to low 80s, whereas older furnaces will be in the 50s or 60s. ENERGY STAR® qualified oil and gas furnaces have annual fuel utilization efficiency (AFUE) ratings of 83% and 90%, or higher, making them up to 15% more efficient than standard models. Unlike the Seasonal Energy Efficiency Ratio (SEER) and Heating Season Performance Factor (HSPF) ratings, the AFUE does not consider the unit’s electricity use for fans and blowers.
Virginia Cooperative Extension materials are available for public use, reprint, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; M. Ray McKinnie, Administrator, 1890 Extension Program, Virginia State University, Petersburg.
June 9, 2014