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90 percent AFUE Gas Condensing Furnace Review

By: Kelly Burgess on September 01, 2017

Bottom Line

A gas condensing furnace costs more initially, but uses less fuel over time, so the energy savings may be enough to recoup the extra cost. Many states with harsher winters mandate that new furnaces have 90 percent AFUE ratings or greater.


  • Low long-term energy costs
  • Low CO2 emissions
  • You may be able to buy a smaller furnace
  • May qualify for local tax credits and utility company rebates


  • High initial costs
  • Less cost-effective in mild climate
Our Analysis
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Our Analysis

Also known as condensing furnaces, furnaces with AFUE ratings of 90 percent or greater condense the water vapor in exhaust gases to extract additional heat. Venting is directly through a wall to the outside through a PVC pipe, rather than through the chimney. This efficiency comes at a cost, however. Experts say a condensing furnace may cost about $1,000 more than a furnace with an annual fuel utilization efficiency (AFUE) rating of around 80 percent. Installation costs may be higher as well. However, because a condensing furnace will use less fuel over time, the energy savings may be enough to recoup the extra cost. In addition, a condensing furnace will emit less carbon dioxide, which may be an important factor for those concerned about pollution.

Keep in mind that regulations that went into effect in May 2013 mandate furnaces with 90 percent AFUE ratings or greater in 30 northern states; the requirement is for an 80 percent rating in the 20 other, milder-climate states. These regulations only apply to non-weatherized furnaces. As of Jan. 1, 2015, weatherized furnaces need to also meet the 90 percent rating standard in 30 northern states, and an 81 percent AFUE rating in 20 milder-weather states. A condensing furnace with an AFUE of 90 percent or more may qualify for local tax credits or utility rebates. For a complete, state-by-state list of credits and rebates, visit the Database of State Incentives for Renewables & Efficiency (DSIRE) website.

Our Sources

U.S. Department of Energy, Not Dated

This article compares low-, mid-, and high-efficiency heating systems and offers advice on whether to choose a high-efficiency unit. There is also a discussion of the benefits of retrofitting your furnace and boiler, as well as links to tips on saving energy and more information on various types of heating systems.

Editors of ConsumerReports.org, September 2016

This buying guide examines the types of gas furnaces available today and discusses how to determine if your furnace needs to be repaired or should be replaced. For replacement furnaces, the cost differences between high-efficiency furnaces and midrange furnaces are also discussed. Unlike other content on this site, this article is available to nonsubscribers.

U.S. Department of Energy, As of August 2017

These are the most efficient furnaces of 2017 according to the U.S. Department of Energy. All of these models have an AFUE rating of at least 97 percent. Annual operating costs and energy use are also detailed.

Editors of SmarterHouse.org, Not Dated

Editors explain the different types of heating systems, and the best choice for various regions. This site has a lot of information relating to improving energy efficiency and maintaining your system for maximum performance.

Editors of The Family Handyman, Not Dated

In this article, editors of TheFamilyHandyman.com talk to HVAC pros to drill down on a variety of furnace-related topics, such as choosing a furnace and the pros and cons of various furnaces types. They also have tips for choosing a contractor and saving money on the initial purchase.

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