Final answer:
The AFUE efficiency rating is determined through specific tests on a heating system to measure its energy efficiency. The rating is expressed as a percentage and compares the amount of heat generated to the amount of fuel used.
Step-by-step explanation:
The Annual Fuel Utilization Efficiency (AFUE) rating is determined by performing specific tests on a heating system to measure its energy efficiency. To determine the AFUE rating for a furnace, the fuel is burned, and the amount of heat generated is measured. The heat is then compared to the amount of fuel used to calculate the efficiency. The rating is expressed as a percentage, with higher numbers indicating greater efficiency.
For example, if a furnace has an AFUE rating of 80%, it means that 80% of the fuel consumed is converted into heat, while the remaining 20% is lost through the exhaust or other means. This rating allows consumers to compare the energy efficiency of different heating systems before making a purchase decision.
Overall, the higher the AFUE rating, the more efficient the heating system is, resulting in lower energy costs and reduced environmental impact.