AFUE Ratings Guide

If you’re realizing that it’s time to upgrade your furnace, an important first step is to settle on an efficiency rating. This will have an effect on your up-front costs and what you pay for home heating in the future. Use this guide to learn 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 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 estimated by calculating the ratio of the heat coming from your furnace to the amount of gas or diesel it consumes in the process. This calculation factors in the energy lost through exhaust gases, radiation and other variables that decrease efficiency. The result is displayed as a percentage, representing the proportion of fuel converted into heat.

Figuring out a furnace’s AFUE rating entails conducting a common test cycle to measure the heat output and fuel consumption. This test cycle is intended to simulate normal heating conditions over the year, including both on and off periods. The heating system then functions at maximum 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 slowly increased HVAC efficiency ratings over the last few decades with hopes to increase energy efficiency and reduce emissions that harm the ozone/atmosphere. 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 mandated furnaces to be rated 90 AFUE or better. Better AFUE ratings reduce energy consumption, lowers power bills and decreases the environmental consequence of heating your home.

Why Do Gas Furnaces Jump from 80 to 90 AFUE?

When browsing around for new furnaces, you may find many models around 80 and 90 AFUE, with little in between. This is mainly because the technology needed to exceed 80 AFUE triggers a substantial leap 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% lost to the atmosphere through the flue.

Gas furnaces must integrate more advanced technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and alternate heat exchangers. These features help the furnace extract heat from the fuel supply 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 Influence Furnace Prices?

The total price of a furnace with a higher AFUE rating is typically more than that of a lower AFUE-rated furnace. In the end, more advanced technologies come at a higher price. The exact cost difference is determined by the furnace manufacturer, size and efficiency rating.

When evaluating the purchase price of a more efficient furnace, remember the long-term 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 extra up-front investment.

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

Although a higher AFUE rating translates into more efficient home heating and more affordable energy bills, we are not saying every homeowner should choose a 95 AFUE furnace. Here are the factors to take into account when evaluating costs and efficiency ratings:

  • Seasonal weather conditions: The colder the weather, the more frequently your high-efficiency furnace runs, and thus, provides an earlier ROI. Because of this, higher AFUE ratings are most beneficial in cold climates that demand more heating than cooling to keep a comfy indoor temperature.
  • How long you’ll live in this home: If you imagine living in your home for many years, purchasing a high-efficiency furnace may be a smart investment given that it will pay for itself over the next few years in energy savings. But, if you plan to move in the near future, 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 when the price of fuel is higher. You’ll realize the savings each month once your furnace converts a higher percentage of fuel into usable heat for your home.

Get a New Furnace Today

For help determining the ideal heating system for your needs and budget, select Service Experts Heating, Air Conditioning & Plumbing. We can help you weigh the up-front costs and long-term benefits of different AFUE ratings to inform 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.

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