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What is the best forced-air furnace to buy? This expert, unbiased furnace buying guide will help you choose between the major brands to find the right heater for your home and budget.

Is it time for you to buy a new high-efficiency forced-air furnace? Sky-high energy bills, diminishing resources, and environmental concerns have brought a great deal of attention to the topic of home energy efficiency in recent years—especially when it comes to heating. Homeowners are struggling to spend less, use less, and pollute less without giving up the warmth and comfort they’ve come to cherish.


If your old furnace has stopped working entirely, it’s definitely time for a new, high-efficiency furnace. But, even if your old furnace seems to work okay, it might be time to consider replacing it with a more efficient model—to save money over the long run and enjoy more comfort and quiet now.

The efficiency of your furnace can make a major difference in your energy bills.

According to the U.S. Department of Energy (DOE), heating and cooling account for approximately 56 percent of the energy used in a typical U.S. home (the portion for heating is about 30 percent).

Obviously, if you can squeeze more efficiency out of your heating and cooling equipment, you can make a major dent in your monthly energy bills. If you intend to stay in your home for a few years, upgrading from an old, inefficient furnace to a new, high-efficiency model can pay for itself and improve your comfort.

An obsolete furnace can be very expensive

If your furnace was installed before 1992, it is probably obsolete.

In an effort to curb energy waste and pollution, the U.S. Department of Energy (DOE) instituted standards for manufacturers at the beginning of 1992 that required every new furnace to turn at least 78 percent of its fuel into heat. On May 1, 2013, these minimums rose to 80 percent. All new models sold must meet or surpass this; efficiencies climb as high as 98.5 percent with the best models.

So, if your gas or oil-burning furnace was installed before 1992, you’re probably sending 30 percent or more of your energy dollars up the furnace flue, and, by the way, pumping up to 4 tons of carbon dioxide, the “greenhouse gas,” into the atmosphere each year.

In fact, if you have an older forced-air furnace operating at very low efficiencies, it probably produces about half the heat it could be providing on the same amount of fuel.

A Carrier infinity gas furnace in white background.
A high-efficiency furnace can pay for itself through energy savings. Carrier


Determining your furnace’s age

Try to get a fix on how old your furnace is. Open the cabinet and look for dates. Write down the model number and try searching it on the Internet. If you can’t find the approximate date of manufacture, you’ve probably answered the question with a resounding “time to replace.”

If your furnace has a standing pilot light instead of electronic ignition, consider this to be another sign that it is an energy waster.

Making a furnace buying decision

Most furnaces sold in the United States are made by a handful of major manufacturers including Lennox, Trane, and Carrier (which also makes Day and Night and Bryant). In the following articles, we’ll help you sort through the brands, models, features, jargon, warranties, costs, and so forth to ease your decision-making.

The biggest differences between the most expensive and least expensive models boil down to energy efficiency, comfort, and warranties. Now we’ll take a closer look at these factors. For information on determining the right size of furnace, see How to Size a Furnace.

How Furnace Efficiency Is Measured

A furnace uses energy to produce and deliver heat. The more heat it can deliver with a given amount of energy, the better: This is the essence of “efficiency.” Furnace manufacturers strive to produce appliances that both burn fuel efficiently and require minimal energy (typically electricity) to run the blowers that circulate the heat to the house.

Furnace fuel efficiency ratings

The measurement for furnace fuel efficiency is called an Annual Fuel Utilization Efficiency (AFUE) rating. All new furnaces are posted with this rating, generally in the form of a yellow “EnergyGuide” label that’s required by the Federal Trade Commission (FTC). Yellow EnergyGuide labels list estimated annual operating costs for furnaces under specific conditions; these are meant for comparison shopping only.

Yellow EnergyGuide label for furnaces, indicating efficiency rating and US states allowed.

AFUE ratings run from the 80 percent minimum to 98.5 percent. The meaning of this percentage is very simple: This is the ratio of the furnace’s annual fossil fuel that is converted into usable heat. In other words, the highest-performing model converts 98.5 percent of its fuel into heat.

A Lennox infinity gas furnace in white background.
This furnace delivers over 98 percent efficiency. Lennox

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Saving energy dollars

Another way to think about this is to consider that 98.2 cents out of every dollar spent for energy to heat your home is converted to heat. With a lower performing model, 20 cents or more of every dollar is wasted.

Those dollars can add up in a hurry at today’s energy prices. (The AFUE rating does not take into account the loss of heat that occurs in the duct work delivery system; this loss can be as high as 35 percent with attic duct work.)

High efficiency or not?

Though most makers call their furnaces “high efficiency,” the DOE only refers to units with an AFUE higher than 90 percent as “high efficiency” and models with an 80 percent to 83 percent AFUE as “mid efficiency.”

As minimums rise, these descriptions become even less meaningful. Just pay attention to the percentage. And be aware that, depending upon where you live, it may not be worth it to spend the big bucks for the highest efficiency unit available. Though these units usually make sense in cold climates, the savings might not pencil out if you live in a mild-winter climate.

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About Don Vandervort
Don Vandervort has developed his expertise for more than 30 years as a remodeler and builder, Building Editor for Sunset Books, Senior Editor at Home Magazine, author of more than 30 home improvement books, and writer of countless magazine articles. He appeared for 3 seasons on HGTV’s “The Fix,” and served as MSN’s home expert for several years. Don founded HomeTips in 1996. Read more about Don Vandervort