AFUE Ratings Guide

If you’re realizing that it’s time to upgrade your furnace, an important first step is to decide on an efficiency rating. This will impact your up-front costs and what you pay for home heating down the road. This guide is intended to inform you about AFUE ratings and how they affect you. 

What Is an AFUE Rating? 

AFUE stands for Annual Fuel Utilization Efficiency. It is a standard for measuring how efficiently a furnace or boiler switches fuel into heat for your home within 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 estimated by calculating the ratio of a furnace’s heat output to the amount of fuel it utilizes in the process. This calculation accounts for the energy lost through exhaust gases, radiation and other factors that diminish efficiency. The result is displayed as a percentage, representing the share of fuel converted into heat. 

Determining a heating system’s AFUE rating includes conducting a common test cycle to quantify the heat output and fuel consumption. This test cycle is structured 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 extended period to define 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 last several decades in an effort to increase 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 lessen energy consumption, lowers energy bills and curbs 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, and not a whole lot else to consider. This is mainly because the technology needed to exceed 80 AFUE triggers a considerable rise in performance. 

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

Gas furnaces must integrate more sophisticated technology to achieve 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 source more effectively, increasing efficiency from 80 to 90 AFUE or higher. Today’s best furnaces cap out at around 98.5 AFUE. 

How Do AFUE Ratings Determine Furnace Prices? 

The total price of a furnace with a higher AFUE rating is typically higher than that of a lower AFUE-rated furnace. Basically, more sophisticated technologies come at a cost. The exact cost difference depends on the furnace make, size and efficiency rating. 

When considering the up-front cost of a more efficient furnace, don’t forget the future energy savings that awaits you. The real chance to save money on fuel bills for the next decade or longer helps you to recoup the higher up-front investment. 

Does It Make Sense to Buy a Furnace with the Highest AFUE Rating Possible? 

While a higher AFUE rating translates into more efficient home heating and more affordable energy bills, we are not saying all homeowners should buy a 95 AFUE furnace. Listed below are some factors to think about when reviewing costs and efficiency ratings:  

• Local weather: The colder the temperatures, the more frequently your high-efficiency furnace runs, and thus, provides an earlier ROI. Therefore, higher AFUE ratings are most appropriate in cold climates that demand more heating than cooling to maintain a comfy indoor temperature. 

• How long will you live there?: If you imagine living in your home for many years, buying a high-efficiency furnace might be a wise investment because it will pay for itself over the next few years 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. 

• The cost of fuel: The affect 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. 

Consider a New Furnace Today 

For help determining the perfect heating system for your needs and budget, turn to 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 guide your decision. We are so certain that you’ll love working with Service Experts that we offer a 100% satisfaction guarantee! To learn more or to schedule a complimentary furnace installation estimate, please call a Service Experts office near you

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