What is the minimum efficiency rating for furnaces?

The minimum efficiency rating for furnaces is determined by the U.S. Department of Energy and is typically set at 78%. This standard indicates that a furnace must be able to convert at least 78% of the fuel it consumes into usable heat. This requirement helps ensure energy efficiency and environmental responsibility, reflecting a shift towards encouraging higher efficiency in heating systems.

Furnaces with efficiency ratings below this threshold are not commonly accepted in modern applications, and higher efficiency ratings are often preferred for optimal energy savings and reduced utility costs. While many high-efficiency models available today far exceed this minimum requirement, understanding the baseline helps consumers recognize the least efficient options in the market.