AFUE Ratings Guide

If you’re considering an upgrade to your furnace, an early choice in the process is to settle on 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 is an acronym 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 output of heat from the furnace or boiler to the amount of gas or diesel it requires in the process. This calculation accounts for the energy lost through exhaust gases, radiation and other variables that diminish efficiency. The result is shown as a percentage, representing the proportion of fuel converted into heat.

Calculating a heating system’s AFUE rating includes conducting a conventional test cycle to quantify the heat output and fuel consumption. This test cycle is structured to simulate normal heating conditions in the course of the year, including both on and off periods. The heating system is then run at peak 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 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 called for furnaces to be rated 90 AFUE or higher. Better AFUE ratings lessen energy consumption, lowers power bills and reduces 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 find many models around 80 and 90 AFUE, and not a whole lot else to consider. This is because the technology necessary to exceed 80 AFUE forces a considerable 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 convert 80% of the fuel they consume into heat, with the remaining 20% sacrificed to the atmosphere through the flue.

Gas furnaces must integrate more innovative technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and secondary heat exchangers. These solutions help the furnace grab heat from the fuel source more effectively, improving 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 total price of a furnace with a higher AFUE rating is normally higher than that of a lower AFUE-rated furnace. Not surprisingly, more advanced technologies come with a higher price tag. The exact cost difference depends on the furnace manufacturer, size and efficiency rating.

When evaluating the up-front cost of a more efficient furnace, don’t forget the long-term energy savings that awaits you. The real chance to save money on utility bills for the next ten years or longer will definitely allow you to recoup the extra up-front investment.

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

Though a higher AFUE rating translates into more efficient home heating and lower energy bills, we are not saying everyone should purchase a 95 AFUE furnace. Here are the factors to think about when evaluating costs and efficiency ratings:

  • Local weather: The colder the weather, the more frequently your high-efficiency furnace operates, and thus, provides an earlier ROI. For that reason, higher AFUE ratings are most appropriate in cold climates that require more heating than cooling to maintain a comfortable indoor temperature.
  • When do you plan to move?: If you picture living in your home for quite a while, purchasing a high-efficiency furnace could be a wise investment since it will pay for itself over the next few years in energy savings. But, if relocating is in your plans within the next couple of years, the extra cost of a higher AFUE-rated furnace probably does not make sense.
  • Energy prices: The affect of an efficient furnace is more evident when energy costs are higher. 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

When trying to find the perfect furnace system for your needs and budget, choose Mid-State Air Conditioning, Heating & Plumbing. We can help you sort 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! To find out more or to schedule a free furnace installation estimate, please get in touch with a Service Experts office near you.

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