What is the minimum established efficiency rating for furnaces set by the U.S. government?

The minimum established efficiency rating for furnaces set by the U.S. government, particularly for residential gas furnaces, is 80%. This standard, which applies to new furnace installations, is part of the Department of Energy's efforts to ensure energy efficiency and reduce emissions. The rating reflects the annual fuel utilization efficiency (AFUE), which measures how effectively a furnace converts fuel into heat over the course of a year.

A furnace with an efficiency rating below this threshold would not meet legal requirements for installation in many areas, indicating that it would consume more fuel and have higher operating costs over time, as well as a poorer environmental impact. This regulation encourages consumers to invest in more energy-efficient systems, leading to cost savings on utility bills and a reduction in the carbon footprint of heating systems.

Furnaces with efficiency ratings lower than 80% are less common today, as manufacturers have increasingly focused on producing higher-efficiency models to comply with energy standards and meet consumer demand for efficiency and performance.