What Does an AFUE Rating Mean?

What is an AFUE rating for heating equipment and why should it matter to Montgomery area homeowners? In our most recent blog, the technicians at Hans Heating and Air explain this important HVAC industry measure and what it tells homeowners about their furnaces. 

What is an AFUE Rating?

AFUE is an acronym that stands for Annual Fuel Utilization Efficiency. Expressed as a percentage, this ratio shares how efficiently a furnace or boiler uses the heating fuel it consumes, whether it be natural gas, propane, or oil. To determine the AFUE rating for a particular furnace unit, the total heat output is divided by the unit’s total energy input. 

A furnace’s AFUE rating shares the percentage of heating fuel that is effectively turned into energy to heat the home. As an example, an 80% AFUE furnace uses 80 percent of the energy it takes in to produce heat energy for the home; the other 20 percent is waste.

How Can Homeowners Use AFUE Ratings?

As you shop for a new furnace to install in your Montgomery home, you can look at a unit’s Annual Fuel Utilization Efficiency rating to judge how efficiently it operates. The most efficient furnaces on the market today top out at about 98.5% AFUE. The minimum allowable AFUE for newly manufactured furnaces in the United States is 80%. 

When replacing an older furnace, the AFUE rating can have a drastic impact on your heating costs. Older heating units weren’t legally required to offer the same AFUE levels today’s manufacturers are bound by. The Department of Energy first began setting standards for AFUE ratios of heating equipment in 1975, issuing a guidance on minimum efficiency ratings. The first minimum Annual Fuel Utilization Efficiency rating was set at 78% in 1987. Effective in 2015, the minimum AFUE was raised to 80%.

Furnaces lose efficiency every year they operate, so if your older furnace has been in service for 15 to 20 or more years, its efficiency is likely nowhere near where you think it might be. Replacing the furnace with a standard 80% AFUE rating unit generates noticeable energy savings and lowers utility costs in many of these cases. Choosing a high efficiency unit with an AFUE rating in the 90% range generates even higher energy savings.

Features of High AFUE Furnaces

To achieve high AFUE ratios, HVAC manufacturers build their systems using new technologies that enhance efficient performance. Common features seen on models with an Annual Fuel Utilization Efficiency rating of 90% or higher include:

  • Secondary heat exchanger, which allows more heat energy to be harnessed for heating air.
  • Variable speed blowers that allow air distribution at higher or lower speeds to conserve energy.
  • Variable heat output, which allows the furnace to vary the amount of heat produced depending on the needs of the household.
  • Hot surface or direct spark ignition systems replace the pilot lights used in older furnaces for increased efficiency.
  • Improved filtration systems help boost the home’s indoor air quality.

Find the Right Furnace with Help from Hans

Hans Heating and Air aims to help our customers understand what an Annual Fuel Utilization Efficiency rating is and how it applies to their purchase decisions. When you shop for a new furnace with our team, you’ll receive expert guidance as you evaluate your options. Contact us to schedule a consultation today!

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