AFUE Ratings Guide

If you’re realizing that it’s time to upgrade your furnace, one of the first steps is to determine an efficiency rating. This will impact your up-front costs and what you pay for home heating as time goes on. Use this guide to learn more about AFUE ratings and how they affect you.

What Is an AFUE Rating?

AFUE stands for Annual Fuel Utilization Efficiency. It is a standard for measuring 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 determined by calculating the ratio of the heat coming from your furnace to the fuel it consumes in the process. This calculation takes into account the energy lost through exhaust gases, radiation and other variables that diminish efficiency. The result is expressed as a percentage, representing the share of fuel converted into heat.

Determining a heating system’s AFUE rating includes conducting a standard test cycle to measure the heat output and fuel consumption. This test cycle is intended to simulate typical heating conditions over the year, including both hot and cold periods. The heating system operates at full capacity for a prolonged period to establish 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 last few decades with hopes to improve energy efficiency and reduce carbon monoxide from the 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 greater. Better AFUE ratings reduce energy consumption, lowers utility bills and reduces 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 due to the technology needed to exceed 80 AFUE creates a considerable leap in performance.

The 80 AFUE threshold has been the minimum expectation for gas furnaces in the USA 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 incorporate more advanced technology to secure higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and alternate heat exchangers. These features help the furnace pull heat from the fuel source more effectively, boosting efficiency from 80 to 90 AFUE or higher. Today’s best furnaces cap out at approximately 98.5 AFUE.

How Do AFUE Ratings Impact Furnace Prices?

The cost of a furnace with a higher AFUE rating is normally more than that of a lower AFUE-rated furnace. Basically, more innovative technologies come at a cost. The exact cost difference is determined by the furnace make, size and efficiency rating.

When considering the purchase price of a more efficient furnace, remember the future energy savings that awaits you. The ability to save money on utility bills for the next 10 years or longer will permit you to recoup the extra up-front investment.

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

While a higher AFUE rating leads to better home heating and lower energy bills, we are not recommending that all homeowners should buy a 95 AFUE furnace. Listed below are some factors to take into account when comparing costs and efficiency ratings:

  • Seasonal weather conditions: The colder the climate, the longer your high-efficiency furnace operates, and thus, provides an earlier ROI. Because of this, higher AFUE ratings are most appropriate in cold climates that demand more heating than cooling to sustain a comfortable indoor temperature.
  • How long will you live there?: If you envision living in your home for a long time, choosing a high-efficiency furnace may be a good investment given that it will pay for itself over the coming 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.
  • Energy prices: The affect of an efficient furnace is more noticeable when energy costs are higher. You’ll see the savings in your bottom line as your furnace converts a higher percentage of fuel into usable heat for your home.

Install a New Furnace Today

If you’re looking for the best heating system for your needs and budget, rely on 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 find out more or to schedule a free furnace installation estimate, please contact a Service Experts office near you.

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