The complete buyer’s guide to furnaces – Understanding furnace energy efficiency (AFUE)

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When looking into purchasing a new furnace, knowing the efficiency ratings should be included in your decision as furnaces are becoming more and more energy efficient. Knowing this rating could be the link between your wallet and your comfort. The budget of your furnace is primarily impacted by efficiency which can be determined through the Annual Fuel Use Efficiency ratings, also known as AFUE.

Measuring AFUE

This number is found by creating a ratio of useful energy out and energy input. It is the measure of the annual output of the heat through the furnace compared to the amount of annual fossil fuel energy taken in by the furnace. Basically, the higher the AFUE the higher the efficiency use. The rating is read as a percentage of fuel paid for versus fuel returned as heat. For example, a furnace with a 98% AFUE rating returns 98% of the fuel you pay for as heat. The remaining 2% is lost in the conversion and burning process.

Gas vs. electric furnace

Gas furnaces are considered to be extremely efficient since the majority have a 90% efficiency rating. The 10% of energy loss comes from the ability of energy to escape through the chimney and other ventilated areas. Since there is no chimney involved when it comes to electric furnaces, the AFUE can range anywhere from 95% to 100%. Although high in efficiency, electric furnaces can also inflict higher electricity costs making them a much less economical choice than gas furnaces.

How much $$$ can you save?

It’s clear that switching to a newer and more efficient furnace will lead to cost savings, but many homeowners want to know exactly how much they can expect to save. Will replacing your old furnace with a new one allow you to save for a trip to Italy? Or a trip to McDonald’s? Let’s compare the cost of an old furnace with a 50% AFUE rating to a new furnace with a 95% AFUE rating. For every $100 a homeowner with the 50% AFUE model spends, a homeowner with a 95% AFUE model would only spend $53. This could save you hundreds of dollars in savings in just one year. Over the lifetime of the furnace it will pay for itself, a replacement, and yes, a trip for the whole family to Italy!

Get a measurement today

Sometimes calculations can get tedious and even confusing. If you don’t know what the AFUE for your furnace is or if you should be looking to replace it, contact us today for consultation by one of our HVAC professionals.