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 rating selection will influence your up-front costs and what you pay for home heating as time goes on. This guide is intended to inform you about AFUE ratings and how they affect you. 

What Is an AFUE Rating? 

AFUE is an acronym for Annual Fuel Utilization Efficiency. It is a measure of how efficiently a furnace or boiler converts 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 the output of heat from the furnace or boiler to the amount of gas or diesel it consumes in the process. This calculation accounts for the energy lost through exhaust gases, radiation and other elements that decrease efficiency. The result is shown as a percentage, representing the share of fuel converted into heat. 

Determining a furnace or boiler’s AFUE rating entails conducting a conventional test cycle to quantify the heat output and fuel consumption. This test cycle is intended to simulate ordinary heating conditions in the course of the year, including both on and off periods. The heating system is then run at full 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 slowly increased HVAC efficiency ratings over the past several decades in an attempt to increase 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 greater. Better AFUE ratings reduce energy consumption, lowers power 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 find many models around 80 and 90 AFUE, but not much in between. This is mainly because the technology required to exceed 80 AFUE causes a significant leap in performance. 

The 80 AFUE threshold has been the minimum requirement for gas furnaces in the United States since the 1990s. At this level, furnaces convert 80% of the fuel they consume into heat, with the remaining 20% lost to the atmosphere through the flue. 

Gas furnaces must use more innovative technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and supplementary heat exchangers. These solutions 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 approximately 98.5 AFUE. 

How Do AFUE Ratings Influence Furnace Prices? 

The price of a furnace with a higher AFUE rating is typically higher than that of a lower AFUE-rated furnace. After all, more innovative technologies come at a cost. The exact cost difference depends on the furnace brand, size and efficiency rating. 

When considering the purchase price of a more efficient furnace, keep in mind the future energy savings that awaits you. The ability to save money on fuel bills for the next decade or longer helps you to recoup the higher up-front investment. 

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

While a higher AFUE rating results in more effective home heating and more affordable energy bills, we are not recommending that everyone should choose a 95 AFUE furnace. Below are a few factors to consider when comparing costs and efficiency ratings:  

  • Local weather: The colder the weather, the more frequently your high-efficiency furnace operates, and the faster you will realize an overall savings from your investment. For that reason, higher AFUE ratings are most suitable in cold climates that take more heating than cooling to maintain a pleasant indoor temperature. 
  • How long will you live there?: If you picture living in your home for many years, choosing a high-efficiency furnace could be a good investment given that it will pay for itself over time in energy savings. On the other hand, if relocating is in your plans within the next couple of years, the extra cost of a higher AFUE-rated furnace probably does not make sense. 
  • Energy prices: The affect of an efficient furnace is more pronounced when energy costs are 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. 

Install a New Furnace Today 

For help determining the perfect heating system for your needs and budget, rely on Service Experts Heating, Air Conditioning & Plumbing. We can help you sort out the initial costs and long-term benefits of different AFUE ratings to inform your decision. We know you’ll love working with Service Experts so much so 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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