AFUE Ratings Guide

If you’re realizing that it’s time to upgrade 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 in the future. 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 standard for measuring how efficiently a furnace or boiler changes 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 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 factors that decrease efficiency. The result is expressed as a percentage, representing the amount of fuel converted into heat. 

Figuring out a furnace’s AFUE rating entails conducting a common test cycle to quantify the heat output and fuel consumption. This test cycle is designed to simulate normal heating conditions in the course of the year, including both in-season and out-of-season periods. The heating system operates at maximum 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 steadily 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 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 better. Better AFUE ratings reduce energy consumption, lowers power bills and decreases 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 as a result of the technology needed to exceed 80 AFUE causes 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% lost 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 techniques 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 around 98.5 AFUE. 

How Do AFUE Ratings Influence Furnace Prices? 

The cost of a furnace with a higher AFUE rating is normally higher than that of a lower AFUE-rated furnace. In the end, more advanced technologies come at a cost. The exact cost difference is determined by 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 potential to save money on utility bills for the next 10 years or longer helps you to recoup the higher up-front investment. 

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

While a higher AFUE rating leads to more effective home heating and lower energy bills, we are not recommending that all homeowners should choose a 95 AFUE furnace. Here are the factors to think about when contrasting costs and efficiency ratings:  

• Seasonal weather conditions: The colder the temperatures, the longer your high-efficiency furnace operates, and thus, provides an earlier ROI. For that reason, higher AFUE ratings are most suitable in cold climates that take more heating than cooling to maintain a pleasant indoor temperature. 

• How long you’ll live in this home: If you envision living in your home for a long time, purchasing a high-efficiency furnace may be a smart investment because it will pay for itself over the coming years 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 probably does not make sense. 

• Energy prices: The affect of an efficient furnace is more evident if your energy costs are high. You’ll realize the savings each month as your furnace converts a higher percentage of fuel into usable heat for your home. 

Get a New Furnace Today 

For help determining the best furnace system for your needs and budget, select 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! To learn more or to schedule a free furnace installation estimate, please call a Service Experts office near you

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