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. That first choice will influence your up-front costs and what you pay for home heating as time goes on. 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 a measure of how efficiently a furnace or boiler switches 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 the output of heat from the furnace or boiler 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.

Figuring out a furnace or boiler’s AFUE rating involves conducting a conventional test cycle to assess the heat output and fuel consumption. This test cycle is designed to simulate typical heating conditions over the year, including both on and off periods. The heating system is then run 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 gradually increased HVAC efficiency ratings over the past several decades with hopes to encourage energy efficiency and reduce carbon monoxide from the atmosphere. 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 required furnaces to be rated 90 AFUE or greater. Better AFUE ratings cut down energy consumption, lowers energy 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, but not much in between. This is due to the technology necessary to exceed 80 AFUE causes a substantial jump in performance.

The 80 AFUE threshold has been the minimum expectation 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% sacrificed to the atmosphere through the flue.

Gas furnaces must use more sophisticated technology to achieve higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and supplementary heat exchangers. These solutions help the furnace grab heat from the fuel supply more effectively, improving efficiency from 80 to 90 AFUE or higher. Today’s most popular furnaces cap out at about 98.5 AFUE.

How Do AFUE Ratings Impact 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 sophisticated technologies come at a higher price. The exact cost difference will depend on the furnace manufacturer, size and efficiency rating.

When thinking about the purchase price of a more efficient furnace, don’t forget the ongoing energy savings that awaits you. The potential to save money on utility bills for the next decade or longer will permit you to recoup the extra up-front investment.

Should You Buy a Furnace with the Highest AFUE Rating Possible?

Although a higher AFUE rating translates into more efficient home heating and lower energy bills, we are not recommending that everyone should buy a 95 AFUE furnace. Here are the factors to take into account when evaluating costs and efficiency ratings:

  • Climate: The colder the weather, the more your high-efficiency furnace runs, and the faster you will realize an overall savings from your investment. For that reason, higher AFUE ratings are most beneficial in cold climates that demand more heating than cooling to sustain a comfortable indoor temperature.
  • How long will you live there?: If you picture living in your home for a long time, choosing a high-efficiency furnace may be a wise investment since it will pay for itself over the coming years in energy savings. However, if relocating is in your plans within the next couple of 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 evident if your energy costs are high. 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 perfect furnace system for your needs and budget, choose Service Experts Heating, Air Conditioning & Plumbing. We can help you sort out the up-front costs and long-term benefits of different AFUE ratings to steer your decision. We know you’ll love working with Service Experts so much so that we offer a 100% satisfaction guarantee! To learn more or to schedule a complimentary furnace installation estimate, please get in touch with a Service Experts office near you.

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