AFUE Ratings Guide

If you’re considering an upgrade to your furnace, an important first step is to settle on an efficiency rating. That first choice will impact your up-front costs and what you pay for home heating down the road. With this handy guide, you’ll understand more about AFUE ratings and how they affect you.

What Is an AFUE Rating?

AFUE is short 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 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 the heat coming from your furnace to the fuel it consumes in the process. This calculation accounts for the energy lost through exhaust gases, radiation and other variables that decrease efficiency. The result is expressed as a percentage, representing the amount of fuel converted into heat.

Calculating a heating system’s AFUE rating includes conducting a conventional test cycle to assess the heat output and fuel consumption. This test cycle is structured to simulate normal heating conditions throughout the year, including both on and off periods. The heating system operates at full 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 slowly increased HVAC efficiency ratings over the past several decades in order to improve energy efficiency and reduce emissions that harm the ozone/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 required furnaces to be rated 90 AFUE or better. Better AFUE ratings cut down energy consumption, lowers energy bills and decreases the environmental impact of heating your home.

Why Do Gas Furnaces Jump from 80 to 90 AFUE?

When shopping for new furnaces, you may notice many models around 80 and 90 AFUE, but not much in between. This is as a result of the technology needed to exceed 80 AFUE forces a significant rise in performance.

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

Gas furnaces must incorporate more innovative technology to secure higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and secondary heat exchangers. These features 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 about 98.5 AFUE.

How Do AFUE Ratings Determine Furnace Prices?

The cost 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 with a higher price tag. The exact cost difference depends on the furnace manufacturer, size and efficiency rating.

When evaluating the purchase price of a more efficient furnace, keep in mind the ongoing energy savings that awaits you. The ability to save money on utility bills for the next decade or longer helps you to recoup the additional up-front investment.

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

Though a higher AFUE rating translates into more effective home heating and reduced energy bills, we are not recommending that all homeowners should purchase a 95 AFUE furnace. Listed below are some factors to take into account when reviewing costs and efficiency ratings:

  • Climate: 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 appropriate in cold climates that demand more heating than cooling to maintain a pleasant indoor temperature.
  • How long you’ll live in this home: If you picture living in your home for some time, buying a high-efficiency furnace could be a wise investment because 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 probably does not make sense.
  • The cost of fuel: The impact of an efficient furnace is more pronounced if your energy costs are high. You’ll see the savings in your bottom line once your furnace converts a higher percentage of fuel into usable heat for your home.

Get a New Furnace Today

If you’re looking for the perfect heating system for your needs and budget, rely on 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 steer your decision. We’re so confident you’ll be satisfied with our services 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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