AFUE Ratings Guide

If you’re realizing that it’s time to upgrade your furnace, an important first step is to determine an efficiency rating. This will impact your up-front costs and what you pay for home heating in the future. With this handy guide, you’ll understand more about AFUE ratings and how they affect you. 

What Is an AFUE Rating? 

AFUE is an acronym for Annual Fuel Utilization Efficiency. It is an industry-standard measurement for how efficiently a furnace or boiler changes fuel into heat for your home over the course of a year. The higher the AFUE rating (on a scale of 0% to 100%), the more efficient the system is at converting fuel into usable heat. 

How Is AFUE Measured? 

AFUE ratings are measured by calculating the ratio of a furnace’s heat output to the amount of fuel it requires in the process. This calculation factors in the energy lost through exhaust gases, radiation and other variables that diminish efficiency. The result is stated as a percentage, representing the amount of fuel converted into heat. 

Determining a heating system’s AFUE rating entails conducting a standard test cycle to assess the heat output and fuel consumption. This test cycle is structured to simulate normal heating conditions in the course of the year, including both in-season and out-of-season periods. The heating system then functions at maximum capacity for an extensive period to establish its peak performance. 

What Is the Minimum AFUE Rating in 2023? 

The U.S. Department of Energy (DOE) has gradually increased HVAC efficiency ratings over the past several decades in an effort to improve energy efficiency and reduce carbon monoxide from the atmosphere. In 2023, the minimum rating for new gas furnaces changed to 81 AFUE. From 2015 to 2022, the South and Southwest regions had a minimum rating of 80 AFUE, and the North required furnaces to be rated 90 AFUE or higher. Better AFUE ratings lessen energy consumption, lowers energy bills and decreases the environmental impact of heating your home. 

Why Do Gas Furnaces Jump from 80 to 90 AFUE? 

When searching for new furnaces, you may discover many models around 80 and 90 AFUE, but not much in between. This is because the technology needed to exceed 80 AFUE forces a significant jump in performance. 

The 80 AFUE threshold has been the minimum criteria for gas furnaces in the U.S. since the 1990s. At this level, furnaces transform 80% of the fuel they consume into heat, with the remaining 20% sacrificed to the atmosphere through the flue. 

Gas furnaces must use more advanced technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and alternate heat exchangers. These techniques help the furnace extract heat from the fuel supply more effectively, improving efficiency from 80 to 90 AFUE or higher. Today’s top-rated furnaces cap out at about 98.5 AFUE. 

How Do AFUE Ratings Determine Furnace Prices? 

The cost of a furnace with a higher AFUE rating is normally higher than that of a lower AFUE-rated furnace. Basically, more advanced technologies come with a higher price tag. The exact cost difference depends on the furnace manufacturer, size and efficiency rating. 

When considering the up-front cost of a more efficient furnace, remember the future energy savings that awaits you. The ability to save money on utility bills for the next ten years or longer helps you to recoup the additional up-front investment. 

Should You Buy a Furnace with the Highest AFUE Rating Possible? 

While a higher AFUE rating translates into better home heating and lower energy bills, we are not recommending that all homeowners should purchase a 95 AFUE furnace. Below are a few factors to take into account when contrasting costs and efficiency ratings:  

• Climate: The colder the weather, the longer your high-efficiency furnace runs, and thus, provides an earlier ROI. For that reason, higher AFUE ratings are most suitable in cold climates that need more heating than cooling to sustain a comfortable indoor temperature. 

• How long will you live there?: If you envision living in your home for some time, buying a high-efficiency furnace may be a good investment given that it will pay for itself over the coming years in energy savings. But, if you’re going to move within the next few years, the extra cost of a higher AFUE-rated furnace would not be recommended. 

• The cost of fuel: The benefit of an efficient furnace is more evident when energy costs are higher. You’ll experience noticeable savings as your furnace converts a higher percentage of fuel into usable heat for your home. 

Get a New Furnace Today 

For help determining the best furnace system for your needs and budget, select Service Experts Heating, Air Conditioning & Plumbing. We can help you figure out the up-front costs and long-term benefits of different AFUE ratings to steer your decision. We’re so confident you’ll be satisfied with our services that we offer a 100% satisfaction guarantee! To find out more or to schedule a complimentary furnace installation estimate, please get in touch with a Service Experts office near you

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