AFUE Ratings Guide

If you’re considering an upgrade to your furnace, an important first step is to decide on an efficiency rating. This will impact your up-front costs and what you pay for home heating as time goes on. With this handy guide, you’ll understand more 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 switches 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 estimated by calculating the ratio of a furnace’s heat output to the 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 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 assess the heat output and fuel consumption. This test cycle is designed to simulate normal heating conditions over the year, including both hot and cold periods. The heating system is then run at peak capacity for an extended period to determine 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 last few decades in an effort to encourage 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 lessen energy consumption, lowers utility bills and decreases the environmental consequence of heating your home. 

Why Do Gas Furnaces Jump from 80 to 90 AFUE? 

When shopping 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 causes a significant leap in performance. 

The 80 AFUE threshold has been the minimum requirement 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 integrate more innovative technology to secure higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and secondary heat exchangers. These technologies help the furnace extract heat from the fuel source more effectively, improving efficiency from 80 to 90 AFUE or higher. Today’s best furnaces cap out at around 98.5 AFUE. 

How Do AFUE Ratings Impact Furnace Costs? 

The price of a furnace with a higher AFUE rating is normally more than that of a lower AFUE-rated furnace. After all, more innovative technologies come at a cost. The exact cost difference will depend on the furnace brand, size and efficiency rating. 

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

Does It Make Sense to Buy a Furnace with the Highest AFUE Rating Possible? 

Though a higher AFUE rating leads to more effective home heating and more affordable energy bills, we are not saying every homeowner should buy a 95 AFUE furnace. Below are a few factors to think about when reviewing costs and efficiency ratings:  

• Seasonal weather conditions: The colder the weather, the longer your high-efficiency furnace runs, and the faster you will realize an overall savings from your investment. For that reason, higher AFUE ratings are most suitable in cold climates that demand more heating than cooling to sustain a pleasant indoor temperature. 

• When do you plan to move?: If you envision living in your home for some time, purchasing a high-efficiency furnace may be a smart investment since it will pay for itself over the coming years in energy savings. But, if you plan to move in the near future, the extra cost of a higher AFUE-rated furnace would not be recommended. 

• Fuel costs: The impact of an efficient furnace is more noticeable if your energy costs are high. You’ll see the savings in your bottom line when 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 furnace system for your needs and budget, select 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 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 complimentary furnace installation estimate, please contact a Service Experts office near you

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