AFUE Ratings Guide

If you’re realizing that it’s time to upgrade your furnace, an early choice in the process is to determine an efficiency rating. That rating selection will influence your up-front costs and what you pay for home heating in the coming years. With this handy guide, you’ll understand more about AFUE ratings and how they affect you.

What Is an AFUE Rating?

AFUE is an acronym for Annual Fuel Utilization Efficiency. It is a measure of how efficiently a furnace or boiler switches 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 determined by calculating the ratio of the heat coming from your furnace to the amount of gas or diesel it consumes in the process. This calculation factors in the energy lost through exhaust gases, radiation and other variables that reduce efficiency. The result is shown as a percentage, representing the amount of fuel converted into heat.

Calculating a heating system’s AFUE rating entails conducting a conventional test cycle to quantify the heat output and fuel consumption. This test cycle is designed to simulate normal heating conditions throughout the year, including both on and off periods. The heating system then functions at maximum 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 slowly increased HVAC efficiency ratings over the past several decades in an effort to improve 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 required furnaces to be rated 90 AFUE or greater. Better AFUE ratings cut down energy consumption, lowers utility bills and curbs the environmental impact of heating your home.

Why Do Gas Furnaces Jump from 80 to 90 AFUE?

When researching for new furnaces, you may find many models around 80 and 90 AFUE, but not much in between. This is mainly because the technology necessary to exceed 80 AFUE triggers a significant rise in performance.

The 80 AFUE threshold has been the minimum expectation for gas furnaces in the United States since the 1990s. At this level, furnaces turn 80% of the fuel they consume into heat, with the remaining 20% sacrificed 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 alternate heat exchangers. These technologies help the furnace pull heat from the fuel source more effectively, raising 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 Costs?

The cost of a furnace with a higher AFUE rating is typically more than that of a lower AFUE-rated furnace. Not surprisingly, more innovative technologies come at a higher price. The exact cost difference depends on the furnace make, size and efficiency rating.

When evaluating the purchase price of a more efficient furnace, don’t forget the long-term energy savings that awaits you. The potential to save money on utility bills for the next decade 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?

Though a higher AFUE rating translates into better home heating and more affordable energy bills, this doesn’t necessarily mean every homeowner should choose a 95 AFUE furnace. Listed below are some factors to take into account when comparing costs and efficiency ratings:

• Seasonal weather conditions: The colder the weather, the more your high-efficiency furnace runs, and thus, provides an earlier ROI. For that reason, higher AFUE ratings are most beneficial in cold climates that take more heating than cooling to keep a pleasant indoor temperature.
• How long will you live there?: If you imagine living in your home for a long time, buying a high-efficiency furnace may be a wise investment since it will pay for itself over time in energy savings. On the other hand, if you’re going to move within the next few years, the extra cost of a higher AFUE-rated furnace may not be worth it.
• The cost of fuel: The affect of an efficient furnace is more noticeable 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.

Consider a New Furnace Today

When trying to find the ideal furnace system for your needs and budget, turn to Service Experts Heating & Air Conditioning. We can help you weigh the initial costs and long-term benefits of different AFUE ratings to steer your decision. We know you’ll love working with Service Experts so much so that we offer a 100% satisfaction guarantee! To find out more or to schedule a free furnace installation estimate, please contact a Service Experts office near you.