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AFUE Rating and Furnace Energy Efficiency

Back in July, we wrote a post about the importance of SEER when it comes to determining how energy efficiently an air conditioning system will run. Now that it’s October and people are getting ready for cooler weather, the time has come to think about how efficiently a heating system is going to run. This is especially important in a place like Florida, where heaters don’t run as often: we want to make sure that each time a heating system turns on that it isn’t wasting large amounts of power.

Furnaces have their own efficiency rating, AFUE, which is measured in a different way than SEER.

AFUE: What It Means and How It’s Measured

AFUE stands for “annual fuel utilization efficiency,” and it’s applied to the energy efficiency performance of gas and electric furnaces and boilers. (Heat pumps have their own efficiency rating in heating mode, called HSPF.) AFUE is a percentage that represents how much of a heater’s fuel source it converts into heating power. A furnace that has an AFUE rating of 85% converts 100 units of its fuel source into 85 units of heat, with 15 units going to waste.

To give you an example of the range of AFUE numbers, older furnaces have AFUEs between 55% and 65%. Advances in technology have brought those numbers up to 78%–84%. Special condensing furnaces, which draw extra heat from condensing the exhaust vapor left over in the heat exchangers, can score 90–97% AFUE.

But here’s something to keep in mind when considering a new furnace for installation or replacement: a higher AFUE rating does not necessarily mean a furnace that performs better or even one that will save you money. High AFUE means a furnace that more efficiently converts energy to heat, but if the system is incorrectly sized or matched to a home, all the efficiency in the world won’t help it keep a home comfortable. This is why it is so important to have professionals help you select and install a new furnace.

Call Kool Breeze of Northwest Florida, Inc. when you are looking to have a new furnace installed in Destin, FL.

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