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What is AFUE?

October 22nd, 2009

If you are concerned about the efficiency of your gas furnace, you have probably heard the term AFUE before. But do you understand what it means? The AFUE of your furnace plays a huge role in the money you spend to heat your home each winter.

What is AFUE?

AFUE is a measure of a gas furnace’s energy efficiency. It stands for Annual Fuel Utilization Efficiency and is represented as a percentage. Generally, the higher the AFUE, the more efficient the furnace.

AFUE is used to display the energy of many types of combustion appliances, including:

  • Furnaces
  • Boilers
  • Water heaters

In order to encourage energy efficiency, the U.S. government sets the minimum AFUE for gas furnaces, which is currently at 78%. The AFUE number represents the amount of fuel that is used to create heat. In other words, a furnace with 80% AFUE wastes 20% of the gas that is consumed.

Converting to Dollars and Cents

An even simpler way of approaching AFUE is by looking at the money. Say, for example, you have the 80% AFUE gas furnace mentioned above – for every dollar you spend on natural gas, only 80 cents actually goes toward heating your home’s air while the rest escapes as exhaust.

In contrast, a 95% AFUE furnace uses 95 cents of every dollar to heat your home, which means less fuel used and more money in your pocket.

Taking this a step further, you can see how the savings of a higher rated AFUE furnace can really add up throughout the year. Use this savings calculator (Excel file) from ENERGY STAR to see if a new, higher efficiency furnace make sense for your home.

Other Considerations

AFUE is an important factor in your decision to purchase a new furnace, but as with most large purchases, there are many things to consider as well.

  • Short-term vs. long-term savings – An efficient gas furnace will cost more to purchase up front but offers more energy savings over life of the unit.
  • Electric furnaces – If electric furnaces measured efficiency in AFUE, they would be close to 100%. However, because electricity is much more expensive than natural gas, they don’t make financial sense for most Northern California homeowners.
  • Other heat loss – The AFUE only measures the efficiency of the combustion process of the furnace, it does not take into account heat loss from air duct leakage or lack of insulation.

For more information on AFUE and how to choose the furnace that fits your needs and budget, schedule a free estimate with one of Service Champions’ heating specialists.

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