AFUE Ratings Guide

If you’re thinking about upgrading your furnace, one of the first steps is to determine an efficiency rating. That first choice 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 is short for Annual Fuel Utilization Efficiency. It is an industry-standard measurement for how efficiently a furnace or boiler converts 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 determined by calculating the ratio of the heat coming from your furnace to the amount of fuel it consumes in the process. This calculation accounts for the energy lost through exhaust gases, radiation and other factors that reduce efficiency. The result is displayed as a percentage, representing the amount of fuel converted into heat.

Determining a heating system’s AFUE rating includes conducting a conventional test cycle to assess the heat output and fuel consumption. This test cycle is designed to simulate typical heating conditions throughout the year, including both on and off periods. The heating system operates at full capacity for an extended 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 few decades in an effort to encourage energy efficiency and reduce carbon monoxide from the atmosphere. In 2023, the minimum rating for new gas furnaces was recalculated to be 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 greater. Better AFUE ratings reduce 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 browsing around for new furnaces, you may discover 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 creates a considerable rise in performance.

The 80 AFUE threshold has been the minimum criteria 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 advanced technology to achieve higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and alternate heat exchangers. These features help the furnace grab heat from the fuel source more effectively, raising efficiency from 80 to 90 AFUE or higher. Today’s top-rated furnaces cap out at around 98.5 AFUE.

How Do AFUE Ratings Impact Furnace Prices?

The price of a furnace with a higher AFUE rating is typically more than that of a lower AFUE-rated furnace. Not surprisingly, more sophisticated technologies come with a higher price tag. The exact cost difference is determined by the furnace brand, size and efficiency rating.

When evaluating the purchase price of a more efficient furnace, remember the future energy savings that awaits you. The ability to save money on fuel bills for the next ten years or longer will permit you to recoup the higher up-front investment.

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

Although a higher AFUE rating leads to better home heating and lower energy bills, we are not saying all homeowners should buy a 95 AFUE furnace. Listed below are some factors to consider when contrasting costs and efficiency ratings:

• Seasonal weather conditions: The colder the weather, the longer your high-efficiency furnace runs, and the faster you will realize an overall savings from your investment. Because of this, higher AFUE ratings are most appropriate in cold climates that need 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, buying a high-efficiency furnace may be a smart investment since it will pay for itself over the next few years in energy savings. On the other hand, if you’re going to move within the next few years, the extra cost of a higher AFUE-rated furnace would not be recommended.
• The cost of fuel: The impact of an efficient furnace is more pronounced when energy costs are higher. You’ll experience noticeable savings as your furnace converts a higher percentage of fuel into usable heat for your home.

Get a New Furnace Today

When trying to find the ideal furnace system for your needs and budget, select Service Experts Heating & Air Conditioning. We can help you sort out the up-front costs and long-term benefits of different AFUE ratings to guide your decision. We’re so confident you’ll be satisfied with our services that we offer a 100% satisfaction guarantee! To find out more or to schedule a no-cost furnace installation estimate, please contact a Service Experts office near you.