AFUE Ratings Guide

If you’re thinking about upgrading your furnace, an early choice in the process is to settle on an efficiency rating. That rating selection will have an effect on your up-front costs and what you pay for home heating in the future. This guide is intended to inform you about AFUE ratings and how they affect you. 

What Is an AFUE Rating? 

AFUE is short for Annual Fuel Utilization Efficiency. It is a standard for measuring 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 the output of heat from the furnace or boiler to the fuel it utilizes in the process. This calculation accounts for the energy lost through exhaust gases, radiation and other elements that reduce efficiency. The result is displayed as a percentage, representing the share of fuel converted into heat. 

Determining a heating system’s AFUE rating entails conducting a standard test cycle to quantify 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 is then run 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 steadily increased HVAC efficiency ratings over the past several decades with hopes to improve energy efficiency and reduce emissions that harm the ozone/atmosphere. In 2023, the minimum rating for new gas furnaces was set 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 lessen energy consumption, lowers energy bills and reduces 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 mainly because the technology needed to exceed 80 AFUE causes a considerable jump 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 use more sophisticated technology to achieve higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and secondary heat exchangers. These solutions help the furnace extract heat from the fuel supply more effectively, improving efficiency from 80 to 90 AFUE or higher. Today’s most popular furnaces cap out at approximately 98.5 AFUE. 

How Do AFUE Ratings Affect Furnace Costs? 

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

When evaluating the up-front cost of a more efficient furnace, don’t forget the long-term energy savings that awaits you. The ability to save money on utility bills for the next 10 years or longer will permit you to recoup the higher up-front investment. 

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

Though a higher AFUE rating results in more effective home heating and more affordable energy bills, this doesn’t necessarily mean all homeowners should pick a 95 AFUE furnace. Below are a few factors to consider when evaluating costs and efficiency ratings:  

  • Seasonal weather conditions: The colder the temperatures, the more your high-efficiency furnace runs, and the sooner it will provide a return on investment. Therefore, higher AFUE ratings are most appropriate in cold climates that take more heating than cooling to keep a comfortable indoor temperature. 
  • How long you’ll live in this home: If you imagine living in your home for a long time, buying a high-efficiency furnace could be a smart investment since it will pay for itself over the next few years in energy savings. However, 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. 
  • The cost of fuel: The affect of an efficient furnace is more pronounced when the price of fuel is higher. You’ll see the savings in your bottom line as your furnace converts a higher percentage of fuel into usable heat for your home. 

Install a New Furnace Today 

When trying to find the best furnace system for your needs and budget, choose Service Experts Heating, Air Conditioning & Plumbing. We can help you weigh the initial costs and long-term benefits of different AFUE ratings to inform your decision. We are so certain that you’ll love working with Service Experts that we offer a 100% satisfaction guarantee! For more information or to schedule a free furnace installation estimate, please contact a Service Experts office near you

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