AFUE Ratings Guide

If you’re considering an upgrade to your furnace, an early choice in the process is to determine an efficiency rating. That first choice will have an effect on your up-front costs and what you pay for home heating as time goes on. With this handy guide, you’ll understand more 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 changes 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 measured by calculating the ratio of a furnace’s heat output to the fuel it utilizes in the process. This calculation takes into account the energy lost through exhaust gases, radiation and other variables that diminish efficiency. The result is expressed as a percentage, representing the share of fuel converted into heat. 

Calculating a furnace’s AFUE rating includes conducting a standard test cycle to quantify the heat output and fuel consumption. This test cycle is intended 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 full 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 gradually increased HVAC efficiency ratings over the last several decades in order 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 power bills and curbs the environmental consequence of heating your home. 

Why Do Gas Furnaces Jump from 80 to 90 AFUE? 

When researching for new furnaces, you may discover many models around 80 and 90 AFUE, with little in between. This is as a result of the technology required to exceed 80 AFUE causes 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 convert 80% of the fuel they consume into heat, with the remaining 20% lost to the atmosphere through the flue. 

Gas furnaces must incorporate more innovative 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 pull heat from the fuel supply more effectively, raising efficiency from 80 to 90 AFUE or higher. Today’s most popular furnaces cap out at about 98.5 AFUE. 

How Do AFUE Ratings Influence Furnace Prices? 

The total price of a furnace with a higher AFUE rating is usually higher than that of a lower AFUE-rated furnace. After all, more sophisticated technologies come at a higher price. The exact cost difference is based on the furnace manufacturer, size and efficiency rating. 

When considering the purchase price of a more efficient furnace, don’t forget the ongoing energy savings that awaits you. The real chance to save money on fuel bills for the next decade or longer will allow you to recoup the extra up-front investment. 

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

While a higher AFUE rating translates into more effective home heating and lower energy bills, we are not recommending that every homeowner should purchase a 95 AFUE furnace. Below are a few factors to consider when evaluating costs and efficiency ratings:  

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

• When do you plan to move?: If you imagine living in your home for some time, buying a high-efficiency furnace may be a smart 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 may not be worth it. 

• Fuel costs: The impact of an efficient furnace is more noticeable when the price of fuel is higher. You’ll realize the savings each month when your furnace converts a higher percentage of fuel into usable heat for your home. 

Install a New Furnace Today 

If you’re looking for the perfect 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 guide your decision. We know you’ll love working with Service Experts so much so that we offer a 100% satisfaction guarantee! For more information or to schedule a no-cost furnace installation estimate, please get in touch with a Service Experts office near you

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