AFUE Ratings Guide

If you’re thinking about upgrading your furnace, an important first step is to settle on an efficiency rating. That rating selection will impact your up-front costs and what you pay for home heating in the future. Use this guide to learn 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 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 determined by calculating the ratio of a furnace’s heat output to the fuel it requires in the process. This calculation takes into account the energy lost through exhaust gases, radiation and other variables that reduce efficiency. The result is stated as a percentage, representing the share of fuel converted into heat.

Calculating a furnace or boiler’s AFUE rating entails conducting a standard test cycle to quantify the heat output and fuel consumption. This test cycle is designed to simulate typical heating conditions in the course of 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 with hopes to increase 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 higher. 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 browsing around for new furnaces, you may notice many models around 80 and 90 AFUE, with little in between. This is due to the technology needed to exceed 80 AFUE creates a considerable jump in performance.

The 80 AFUE threshold has been the minimum expectation 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 sophisticated technology to attain higher AFUE ratings, such as two-stage or modulating gas valves, variable-speed blowers and supplementary heat exchangers. These features help the furnace pull heat from the fuel supply 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 Determine Furnace Prices?

The price of a furnace with a higher AFUE rating is normally higher than that of a lower AFUE-rated furnace. In the end, more sophisticated technologies come with a higher price tag. The exact cost difference is based on the furnace brand, size and efficiency rating.

When thinking about the initial cost of a more efficient furnace, remember the ongoing energy savings that awaits you. The ability to save money on energy bills for the next 10 years or longer will permit 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 translates into better home heating and reduced energy bills, we are not recommending that everyone should buy a 95 AFUE furnace. Listed below are some factors to consider when evaluating costs and efficiency ratings:

• Local weather: The colder the climate, the longer your high-efficiency furnace operates, and thus, provides an earlier ROI. Because of this, higher AFUE ratings are most appropriate in cold climates that take more heating than cooling to sustain a comfy indoor temperature.
• How long you’ll live in this home: If you envision living in your home for a long time, buying a high-efficiency furnace could be a smart investment given that it will pay for itself over the coming years 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 benefit of an efficient furnace is more evident 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.

Get a New Furnace Today

If you’re looking for the ideal heating system for your needs and budget, choose Service Experts Heating & Air Conditioning. We can help you figure out the initial costs and long-term benefits of different AFUE ratings to guide your decision. We know you’ll love working with Service Experts so much so 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.