AFUE Ratings Guide

If you’re considering an upgrade to your furnace, one of the first steps 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 down the road. 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 converts 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 measured by calculating the ratio of the heat coming from your furnace to the fuel it requires in the process. This calculation factors in the energy lost through exhaust gases, radiation and other factors that reduce efficiency. The result is stated as a percentage, representing the proportion of fuel converted into heat. 

Calculating a furnace or boiler’s AFUE rating entails conducting a conventional test cycle to measure the heat output and fuel consumption. This test cycle is structured to simulate typical heating conditions in the course of the year, including both in-season and out-of-season periods. The heating system is then run at peak capacity for an extended period to establish 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 past few decades in an attempt to promote 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 required furnaces to be rated 90 AFUE or better. 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 researching for new furnaces, you may notice many models around 80 and 90 AFUE, with little in between. This is as a result of the technology required to exceed 80 AFUE causes a significant leap in performance. 

The 80 AFUE threshold has been the minimum requirement 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% forfeited to the atmosphere through the flue. 

Gas furnaces must incorporate more innovative technology to secure higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and alternate heat exchangers. These techniques help the furnace extract heat from the fuel source more effectively, improving efficiency from 80 to 90 AFUE or higher. Today’s top-rated furnaces cap out at approximately 98.5 AFUE. 

How Do AFUE Ratings Determine Furnace Costs? 

The price of a furnace with a higher AFUE rating is normally more than that of a lower AFUE-rated furnace. Not surprisingly, more sophisticated technologies come with a higher price tag. The exact cost difference depends on the furnace manufacturer, size and efficiency rating. 

When thinking about the up-front cost of a more efficient furnace, keep in mind the ongoing energy savings that awaits you. The ability to save money on fuel bills for the next decade or longer will definitely allow you to recoup the extra up-front investment. 

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

Though a higher AFUE rating translates into better home heating and reduced energy bills, we are not recommending that everyone should choose a 95 AFUE furnace. Below are a few factors to take into account when reviewing costs and efficiency ratings:  

• Climate: The colder the climate, the more your high-efficiency furnace operates, and the faster you will realize an overall savings from your investment. 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 quite a while, buying a high-efficiency furnace could be a wise investment given that it will pay for itself over time in energy savings. On the other hand, if you plan to move in the near future, the extra cost of a higher AFUE-rated furnace may not be worth it. 

• The cost of fuel: The affect of an efficient furnace is more evident 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. 

Install a New Furnace Today 

If you’re looking for the perfect 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 guide 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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