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 influence 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 short 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 determined by calculating the ratio of a furnace’s heat output to the amount of fuel it utilizes 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 share of fuel converted into heat. 

Calculating a furnace or boiler’s AFUE rating involves conducting a common test cycle to measure the heat output and fuel consumption. This test cycle is designed to simulate ordinary heating conditions over the year, including both in-season and out-of-season periods. The heating system is then run at peak capacity for an extensive period to define 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 last few decades in order to increase 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 better. Better AFUE ratings reduce energy consumption, lowers power bills and curbs 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, with little in between. This is as a result of the technology required to exceed 80 AFUE triggers a considerable jump 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 advanced technology to achieve higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and secondary heat exchangers. These solutions help the furnace pull heat from the fuel supply more effectively, increasing efficiency from 80 to 90 AFUE or higher. Today’s most popular furnaces cap out at about 98.5 AFUE. 

How Do AFUE Ratings Determine 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 higher price. The exact cost difference is determined by the furnace manufacturer, size and efficiency rating. 

When considering the initial cost of a more efficient furnace, keep in mind the long-term energy savings that awaits you. The real chance to save money on utility bills for the next decade or longer will 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 better home heating and reduced energy bills, we are not recommending that every homeowner should buy a 95 AFUE furnace. Listed below are some factors to consider when contrasting costs and efficiency ratings:  

• Seasonal weather conditions: The colder the weather, the longer your high-efficiency furnace runs, and the sooner it will provide a return on investment. Therefore, higher AFUE ratings are most appropriate in cold climates that require more heating than cooling to keep a comfortable indoor temperature. 

• How long will you live there?: If you picture living in your home for quite a while, buying a high-efficiency furnace might be a good investment because it will pay for itself over time 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 realize the savings each month once your furnace converts a higher percentage of fuel into usable heat for your home. 

Consider a New Furnace Today 

For help determining the perfect heating system for your needs and budget, turn to Service Experts Heating, Air Conditioning & Plumbing. We can help you weigh the initial costs and long-term benefits of different AFUE ratings to inform your decision. We know you’ll love working with Service Experts so much so that we offer a 100% satisfaction guarantee! For more information or to schedule a free furnace installation estimate, please call a Service Experts office near you

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