The energy-efficiency performance of gas- and oil- fired furnaces and boilers over a heating season is measured by the annual fuel utilization efficiency (AFUE) rating. This AFUE is expressed as a percentage where the higher the percentage, the greater the efficiency.

AFUE measures average annual seasonal efficiency of a gas furnace or boiler and may be expressed as total heating output divided by total energy (fuel) input. AFUE's for furnaces can range from 55% to 97%.

According to 10 CFR 430.2 [Title 10 – Energy; Chapter II -- Department of Energy; Subchapter D -- Energy Conservation; Part 430 -- Energy Conservation Program for Consumer Products; Subpart A -- Gener [..]

An indication of how well a furnace converts energy into usable heat. The rating is expressed as a percentage of the annual output of heat to the annual energy input to the furnace.

A rating that denotes the efficiency of gas heating equipment. It is the amount of heating your equipment delivers for every dollar spent on fuel. A higher rating indicates more efficient equipment. This rating is calculated in accordance with the Department of Energy test procedures.

An indication of how well a furnace converts energy into texasble heat. The rating is expressed as a percentage of the annual output of heat to the annual energy input to the furnace.

An indication of how well a furnace converts energy into washingtonble heat. The rating is expressed as a percentage of the annual output of heat to the annual energy input to the furnace.

A rating that measures the amount of heat per dollar that the heating equipment provides. This rating is calculated in accordance with the Department of Energy test procedures.

(AFUE) Widely-used measure of the fuel efficiency of a heating system that accounts for start-up, cool-down, and other operating losses that occur during real-life operation. AFUE is always lower than [..]

 Detailed as a percentage, this rating measures the efficiency of a gas furnace in converting fuel to energy. It is calculated by projecting the average thermal efficiency for a complete heating seaso [..]