February 16, 2017
By Mark Paup

The Efficiency Question with Furnaces and Boilers: How Important Is It?

Updated January 29, 2024

You may be in the middle of trying to decide whether or not to have a new gas furnace or boiler put in. You can always contact our team to help you make the decision. We’ll assess your current system and give you honest answers about the best way forward.

If you do decide that a new heating system installation is the best option, you then have some other decisions to make. You will probably want to stay with the type of system you currently have, i.e., replacing a furnace with a new furnace or replacing a boiler with a new boiler. (Switching from one to the other requires major home retrofit work.) But newer units have higher efficiencies than older ones. Should you just automatically choose the unit with the highest efficiency that you can afford? And what do the furnace and boiler efficiency numbers mean?

AFUE Is the Measure of Boiler and Furnace Efficiency

We’ll answer the second question first because it is important to have some knowledge about how gas furnace and boiler efficiency is determined. AFUE stands for annual fuel utilization efficiency. It’s a percentage that tells how much of the heating system’s fuel supply is converted into actual thermal energy. For example, if a boiler has an AFUE of 80%, that means that for every 100 units of natural gas that the boiler burns, 80 units turn into thermal energy to heat the house, and 20 units are lost to exhaust, standing heat loss, and other sources. AFUE is measured over a year, so on any given day a furnace or boiler may work a bit higher or lower than their rating.

Efficiency Is Important, But It Is Not the Only Important Factor

The newer models of natural gas boilers and furnaces can achieve incredibly high AFUE ratings that improve over older models, in some cases by 20%. A condensing furnace can have an AFUE of 98.5%, which is a tremendous leap from furnaces that once only had 70% AFUE.

But just because a furnace or boiler has a high AFUE rating doesn’t mean it will automatically save you money. A heating system that is improperly sized and matched to a home will be a huge energy waster and might not be able to adequately heat the space at all—and that’s true no matter how efficient it is. Also, higher efficiency models cost more to install upfront, and this might not be the best match for your current budget.

This is why you must always look to trained HVAC professionals when it’s time for a new heating system installation. A wrong choice will have extensive repercussions, and usually, the only way to fix the problems is to replace the furnace or boiler.

You can count on us to see that you have the best heating system replacement, whether a furnace or boiler. We offer extensive furnace and boiler service in Ankeny, IA.

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Contact Us Today for HVAC Service!

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