AFUE Ratings Guide

If you’re thinking about upgrading your furnace, an important first step is to determine an efficiency rating. That rating selection will influence 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 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 measured by calculating the ratio of a furnace’s heat output to the amount of gas or diesel it utilizes in the process. This calculation takes into account the energy lost through exhaust gases, radiation and other factors that diminish efficiency. The result is expressed as a percentage, representing the share of fuel converted into heat. 

Determining a furnace or boiler’s AFUE rating involves conducting a conventional test cycle to assess the heat output and fuel consumption. This test cycle is intended to simulate typical 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 a prolonged period to define 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 greenhouse gas emissions. 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 required furnaces to be rated 90 AFUE or higher. Better AFUE ratings lessen energy consumption, lowers energy bills and reduces the environmental impact 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, and not a whole lot else to consider. This is as a result of the technology needed to exceed 80 AFUE forces a significant leap in performance. 

The 80 AFUE threshold has been the minimum criteria for gas furnaces in the USA since the 1990s. At this level, furnaces convert 80% of the fuel they consume into heat, with the remaining 20% lost to the atmosphere through the flue. 

Gas furnaces must incorporate more innovative technology to achieve higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and secondary heat exchangers. These technologies help the furnace grab heat from the fuel supply more effectively, raising efficiency from 80 to 90 AFUE or higher. Today’s best furnaces cap out at approximately 98.5 AFUE. 

How Do AFUE Ratings Influence Furnace Prices? 

The cost of a furnace with a higher AFUE rating is usually more than that of a lower AFUE-rated furnace. After all, more sophisticated technologies come at a higher price. The exact cost difference is determined by the furnace brand, size and efficiency rating. 

When thinking about the initial cost of a more efficient furnace, don’t forget the future energy savings that awaits you. The potential to save money on energy bills for the next 10 years or longer will definitely allow 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 reduced energy bills, this doesn’t necessarily mean everyone should pick a 95 AFUE furnace. Below are a few factors to take into account when contrasting costs and efficiency ratings:  

  • Local weather: The colder the climate, the longer your high-efficiency furnace operates, and the faster you will realize an overall savings from your investment. For that reason, higher AFUE ratings are most appropriate in cold climates that take more heating than cooling to keep a comfy indoor temperature. 
  • How long you’ll live in this home: If you envision 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. However, if you’re going to move within the next few years, the extra cost of a higher AFUE-rated furnace would not be recommended. 
  • The cost of fuel: The affect of an efficient furnace is more noticeable if your energy costs are high. 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 

For help determining the perfect heating system for your needs and budget, select Service Experts Heating, Air Conditioning & Plumbing. We can help you weigh the initial costs and long-term benefits of different AFUE ratings to steer your decision. We are so certain that you’ll love working with Service Experts 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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