NATE Gas Heating Practice Exam

What is the minimum Annual Fuel Utilization Efficiency (AFUE) standard for furnaces sold in the U.S. since 1992?

1. 70%

2. 75%

3. 78%

4. 80%

The correct answer is: 78%

The minimum Annual Fuel Utilization Efficiency (AFUE) standard for furnaces sold in the U.S. since 1992 is indeed 78%. AFUE is a measure of a furnace's efficiency in converting fuel to energy, expressed as a percentage. A furnace with a 78% AFUE means that 78% of the energy in the fuel is used for heating, while the remaining 22% is lost during the combustion process and through exhaust. The 78% minimum was established to ensure that modern heating systems provide adequate energy efficiency. This standard was a significant improvement over earlier models, which often had much lower efficiency ratings. Selecting a furnace that meets or exceeds this AFUE standard contributes to better energy use, lower utility bills, and reduced environmental impact. Understanding this standard is crucial for those working in gas heating, as it helps in the selection of efficient heating equipment and compliance with regulations.