Gas furnaces with annual fuel utilization efficiency ratings of 80 percent are less efficient than their 90 percent AFUE counterparts. However, they also have lower initial costs. An 80 percent AFUE gas furnace will cost about $1,000 less than a high-efficiency furnace, and installation costs may be lower as well. Therefore, experts say these furnaces are generally a more cost-effective choice for people who live in milder climates. Although a 90 percent AFUE furnace uses considerably less fuel, an 80 percent furnace will probably still be more efficient than the unit you're replacing, which is most likely an older 60 percent furnace. If you are especially concerned about pollution, you may prefer a more efficient condensing furnace, which will produce lower carbon dioxide emissions than an 80 percent AFUE furnace.
The EnergySavers.gov site, which is run by the U.S. Department of Energy, compares mid-efficiency furnaces with higher- and lower-efficiency furnaces and discusses the potential cost savings of an upgrade. ConsumerReports.org also discusses the cost differences between high- and mid-efficiency furnaces and factors that may affect the payoff period, while the editors at ThisOldHouse.com weigh the pros and cons of upgrading to an 80 percent AFUE furnace.
This article compares low-, mid- and high-efficiency heating systems and offers advice on whether to choose a high-efficiency unit. A table shows the possible cost savings of replacing an older, inefficient furnace.
Review: Furnaces and Boilers, U.S. Department of Energy, Updated Oct. 5, 2010
This buying guide from ConsumerReports.org discusses improvements in furnace efficiency over the years. It discusses the cost differences between high-efficiency furnaces and mid-range furnaces and factors that may affect the payoff period for a higher-efficiency furnace. Unlike other content on this site, this article is available to nonsubscribers.
Review: Gas Furnace Buying Advice, Editors of ConsumerReports.org
3. This Old House
Contractor Richard Trethewy offers advice to a reader considering upgrading her 80 percent efficient furnace to a new high-efficiency furnace. Although Trethewy says this move could cut winter heating bills by as much as 20 percent, he says this isn't enough to offset the costs of the new furnace.
Review: Is It Time to Replace the Furnace?, Richard Trethewy