AFUE Ratings Guide

If you’re considering an upgrade to your furnace, an important first step is to determine an efficiency rating. That first choice will have an effect on your up-front costs and what you pay for home heating in the coming years. 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 changes fuel into heat for your home within a 12-month period. 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 fuel it consumes in the process. This calculation accounts for 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 measure the heat output and fuel consumption. This test cycle is designed 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 an extended 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 past several decades in order to encourage 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 greater. Better AFUE ratings cut down energy consumption, lowers utility bills and decreases 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, but not much in between. This is as a result of the technology necessary to exceed 80 AFUE triggers a considerable rise in performance. 

The 80 AFUE threshold has been the minimum expectation for gas furnaces in the U.S. 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 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 best furnaces cap out at approximately 98.5 AFUE. 

How Do AFUE Ratings Impact Furnace Prices? 

The price of a furnace with a higher AFUE rating is normally 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 manufacturer, size and efficiency rating. 

When considering 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 energy bills for the next ten years or longer helps you to recoup the extra up-front investment. 

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

Though a higher AFUE rating leads to better home heating and more affordable energy bills, this doesn’t necessarily mean everyone should pick a 95 AFUE furnace. Below are a few factors to consider when comparing costs and efficiency ratings:  

• Local weather: The colder the temperatures, the more your high-efficiency furnace runs, and the sooner it will provide a return on investment. Because of this, higher AFUE ratings are most suitable in cold climates that need more heating than cooling to maintain a comfy indoor temperature. 

• When do you plan to move?: If you imagine living in your home for some time, purchasing a high-efficiency furnace may be a good investment since 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 would not be recommended. 

• The cost of fuel: The affect of an efficient furnace is more pronounced when energy costs are higher. You’ll see the savings in your bottom line as your furnace converts a higher percentage of fuel into usable heat for your home. 

Install 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 sort out the up-front 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 complimentary furnace installation estimate, please call a Service Experts office near you

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