AFUE Ratings Guide

If you’re realizing that it’s time to upgrade your furnace, an important first step is to determine an efficiency rating. That first choice will influence your up-front costs and what you pay for home heating in the coming years. 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 measure of how efficiently a furnace or boiler converts 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 the output of heat from the furnace or boiler to the amount of fuel it consumes in the process. This calculation factors in the energy lost through exhaust gases, radiation and other factors that reduce efficiency. The result is expressed as a percentage, representing the amount of fuel converted into heat. 

Figuring out a furnace or boiler’s AFUE rating includes conducting a common test cycle to measure the heat output and fuel consumption. This test cycle is designed to simulate normal heating conditions over the year, including both hot and cold periods. The heating system is then run at full capacity for a prolonged 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 last several decades in an effort to encourage energy efficiency and reduce greenhouse gas emissions. 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 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, with little in between. This is mainly because the technology required to exceed 80 AFUE triggers a significant 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 turn 80% of the fuel they consume into heat, with the remaining 20% lost to the atmosphere through the flue. 

Gas furnaces must integrate more innovative technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and secondary heat exchangers. These techniques help the furnace pull heat from the fuel source more effectively, increasing efficiency from 80 to 90 AFUE or higher. Today’s top-rated furnaces cap out at around 98.5 AFUE. 

How Do AFUE Ratings Influence Furnace Costs? 

The 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 higher price. The exact cost difference depends on the furnace brand, size and efficiency rating. 

When thinking about the up-front cost of a more efficient furnace, keep in mind the future energy savings that awaits you. The ability to save money on utility bills for the next ten years or longer helps you to recoup the additional up-front investment. 

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

Although a higher AFUE rating results in more efficient home heating and reduced energy bills, this doesn’t necessarily mean everyone should choose a 95 AFUE furnace. Below are a few factors to consider when contrasting costs and efficiency ratings:  

• Local weather: The colder the temperatures, the longer your high-efficiency furnace runs, and the sooner it will provide a return on investment. Because of this, higher AFUE ratings are most suitable in cold climates that take more heating than cooling to keep a comfortable indoor temperature. 

• How long will you live there?: If you envision living in your home for a long time, purchasing a high-efficiency furnace could be a smart investment given that it will pay for itself over the next few years in energy savings. But, if you’re going to move within the next few years, the extra cost of a higher AFUE-rated furnace would not be recommended. 

• Energy prices: The affect of an efficient furnace is more noticeable if your energy costs are high. You’ll realize the savings each month as 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 best heating system for your needs and budget, choose Service Experts Heating, Air Conditioning & Plumbing. We can help you weigh 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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