AFUE Ratings Guide

If you’re considering an upgrade to your furnace, one of the first steps is to settle on an efficiency rating. That first choice will impact your up-front costs and what you pay for home heating down the road. Use this guide to learn more about AFUE ratings and how they affect you. 

What Is an AFUE Rating? 

AFUE stands for Annual Fuel Utilization Efficiency. It is an industry-standard measurement for how efficiently a furnace or boiler switches fuel into heat for your home within a 12-month period. 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 estimated by calculating the ratio of a furnace’s heat output to the fuel it utilizes in the process. This calculation factors in the energy lost through exhaust gases, radiation and other variables that decrease efficiency. The result is stated as a percentage, representing the share of fuel converted into heat. 

Determining a heating system’s AFUE rating involves conducting a conventional test cycle to quantify the heat output and fuel consumption. This test cycle is intended to simulate ordinary heating conditions over the year, including both hot and cold periods. The heating system then functions at peak capacity for an extensive period to define its peak performance. 

What Is the Minimum AFUE Rating in 2023? 

The U.S. Department of Energy (DOE) has slowly increased HVAC efficiency ratings over the past several decades in an attempt to improve energy efficiency and reduce greenhouse gas emissions. 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 called for furnaces to be rated 90 AFUE or better. Better AFUE ratings cut down energy consumption, lowers utility bills and decreases the environmental consequence of heating your home. 

Why Do Gas Furnaces Jump from 80 to 90 AFUE? 

When shopping for new furnaces, you may discover many models around 80 and 90 AFUE, with little in between. This is because the technology needed to exceed 80 AFUE triggers a substantial leap in performance. 

The 80 AFUE threshold has been the minimum expectation for gas furnaces in the United States 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 incorporate more innovative technology to secure 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, boosting efficiency from 80 to 90 AFUE or higher. Today’s top-rated furnaces cap out at about 98.5 AFUE. 

How Do AFUE Ratings Influence Furnace Prices? 

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

When considering the purchase price of a more efficient furnace, keep in mind the long-term energy savings that awaits you. The ability to save money on fuel bills for the next ten years or longer will definitely allow you to recoup the higher up-front investment. 

Is It Smart to Buy a Furnace with the Highest AFUE Rating Possible? 

Although a higher AFUE rating leads to more efficient home heating and more affordable energy bills, we are not saying all homeowners should choose a 95 AFUE furnace. Here are the factors to consider when evaluating costs and efficiency ratings:  

• Climate: The colder the climate, the more frequently your high-efficiency furnace runs, and the faster you will realize an overall savings from your investment. Therefore, higher AFUE ratings are most suitable in cold climates that need more heating than cooling to keep a pleasant indoor temperature. 

• When do you plan to move?: If you picture living in your home for many years, buying a high-efficiency furnace could be a wise investment given that it will pay for itself over time in energy savings. But, if you plan to move in the near future, the extra cost of a higher AFUE-rated furnace would not be recommended. 

• Fuel costs: The impact of an efficient furnace is more evident when the price of fuel is higher. You’ll see the savings in your bottom line once your furnace converts a higher percentage of fuel into usable heat for your home. 

Get a New Furnace Today 

When trying to find the best furnace system for your needs and budget, rely on Service Experts Heating, Air Conditioning & Plumbing. We can help you sort 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 learn more or to schedule a no-cost furnace installation estimate, please contact a Service Experts office near you

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