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 have an effect on 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 stands for Annual Fuel Utilization Efficiency. It is a measure of how efficiently a furnace or boiler switches fuel into heat for your home over the course of 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 a furnace’s heat output to the fuel it requires in the process. This calculation takes into account the energy lost through exhaust gases, radiation and other variables that reduce efficiency. The result is expressed as a percentage, representing the amount of fuel converted into heat.

Determining a heating system’s AFUE rating includes conducting a common 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 in-season and out-of-season periods. The heating system is then run at maximum capacity for a prolonged period to determine 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 past few decades in an attempt 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 mandated furnaces to be rated 90 AFUE or higher. Better AFUE ratings cut down 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 searching for new furnaces, you may notice many models around 80 and 90 AFUE, but not much in between. This is due to the technology required to exceed 80 AFUE triggers a substantial leap 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 transform 80% of the fuel they consume into heat, with the remaining 20% forfeited to the atmosphere through the flue.

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

How Do AFUE Ratings Determine Furnace Prices?

The cost of a furnace with a higher AFUE rating is usually more than that of a lower AFUE-rated furnace. Basically, more advanced technologies come at a cost. The exact cost difference is based on the furnace manufacturer, size and efficiency rating.

When considering the up-front cost of a more efficient furnace, don’t forget the future energy savings that awaits you. The potential to save money on utility bills for the next 10 years or longer will permit you to recoup the higher up-front investment.

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

Although a higher AFUE rating leads to better home heating and reduced energy bills, this doesn’t necessarily mean everyone should buy a 95 AFUE furnace. Here are the factors to take into account when comparing costs and efficiency ratings:

  • Local weather: The colder the weather, the more frequently your high-efficiency furnace operates, and thus, provides an earlier ROI. Therefore, higher AFUE ratings are most suitable in cold climates that need more heating than cooling to keep a comfortable indoor temperature.
  • How long you’ll live in this home: If you picture living in your home for many years, purchasing a high-efficiency furnace may be a good investment given that it will pay for itself over time in energy savings. On the other hand, if relocating is in your plans within the next couple of years, the extra cost of a higher AFUE-rated furnace may not be worth it.
  • Fuel costs: The impact of an efficient furnace is more pronounced if your energy costs are high. You’ll experience noticeable savings when your furnace converts a higher percentage of fuel into usable heat for your home.

Consider a New Furnace Today

When trying to find the perfect furnace system for your needs and budget, turn to 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 complimentary furnace installation estimate, please get in touch with a Service Experts office near you.

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