HeatingWhat is an AFUE Rating and Why is it Important?

If you have been out shopping for a furnace or boiler recently, you may have noticed a sticker or sign on a unit that said “AFUE Rating:” followed by a percentage. It looks like an important number, and it is, but most AFUE labels don’t do a very good job of explaining what they actually mean. Read on for an explanation of why you should pay attention to an AFUE rating.


AFUE stands for “Annual Fuel Utilization Efficiency.” It is an evaluation of how well your heating system converts the fuel it burns into thermal energy on an annual basis. For example, an AFUE of 90% means that 90% of the fuel that unit burns is successfully converted into heat and distributed throughout the house. An AFUE of 90% is an extremely good rating. An AFUE of 70% or less is much less desirable. Most modern heating systems are at least 75% AFUE, while older systems can get as low as the mid 50’s. If you have an older heating system, like a cast-iron boiler, you might want to consider replacing it for a unit that won’t waste as much energy.


So why does this matter? Well, the AFUE rating of a unit determines how much fuel it will need to reach and maintain the temperature you want it to maintain. If a unit has a very low AFUE rating, it will burn much more fuel to heat the house sufficiently. This will cost you more money over the course of the year than if you had installed a unit with a higher AFUE rating. With this in mind, it is in your best interest to always look for a heating system with an AFUE rating of at least 80%. This should be relatively easy, as there are federally established requirements for all new heating systems that demand higher AFUE ratings. Even so, it behooves you to always be aware of the efficiency of the unit you buy for your home.

If you need help selecting the most energy efficient heating system for your home, call G&S Heating, Cooling & Electrical, Inc. If you need to schedule reliable heating service in Lynnwood, call us today.


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