A furnace lasts 12-25 years. This is true for furnaces fueled by natural gas (NG), liquid propane (LP) and home heating oil.
The average age of a furnace when replaced is 17 years.
There are many factors that affect how long a furnace will last:
- Quality of the furnace
- Quality of the installation
- How heavily the furnace is used
- Whether it is cleaned and maintained regularly
- Where the furnace is installed
- The furnace’s repair record
- Whether you decide to upgrade the furnace for efficiency or performance
Furnace Longevity Factors
Let’s explore each of these furnaces and the best approach to getting 20+ years from your furnace.
The Quality of the Furnace
Like shoes, cars and guitars, some furnaces are made better than others. There are cheap parts, average parts and premium parts. The more parts the furnace has that are high-quality, the longer it will last.
Why do manufacturers make cheap, average and premium furnaces? People’s budgets and what they need in a furnace are different.
Consider three furnaces that each produce 100,000 BTUs of heat per hour.
- Lennox SLP98V with variable heat, 98.7% efficiency and “perfect” temperature balance. That’s a $4,500 furnace with installation.
- Day & Night QuietComfort furnace with 2-stage heating and 96% efficiency is a $3,500 furnace installed.
- Goodman GMSS96 furnace with single-stage heating and 96% efficiency is about $2,400 installed.
That is a huge price spectrum, and yet the efficiency levels aren’t very different. It’s mostly the performance – staged heating (variable, 2-stage, single-stage) and how comfortably and quietly the furnace heats that causes the price difference.
Did you know? Most brands make affordable, good and premium furnaces to have something for everyone. Heil, for example, makes four lines.
Here they are with expected longevity:
- Ion: Premium (up to 25 years)
- QuietComfort Deluxe: Better (17-22 years)
- QuietComfort: Good (15-18 years)
- Performance: Most affordable (14-17 years)
Quality of Installation
It would not be out of place to make this Factor #1 in furnace longevity. Faulty installation is a major problem.
The US Department of Energy claims, “More than half of new systems in U.S. homes do not perform to their rated efficiency as a result of improper installation. In fact, improper installation can reduce performance by as much as 30%. This not only affects your utility bills, but can lead to a variety of comfort problems, including insufficient dehumidification, dust from leaking ductwork, and poor air distribution.”
There are several steps to correct furnace installation. If the installer fails in any of them, your furnace won’t perform or last as long as it should.
- Sizing the furnace properly. If the furnace is too small, it will work too hard and wear out too soon. If it is too large, it will cycle on and off too often, and that can cause mechanical problems. It will also cause temperature fluctuations that you’ll notice, and you might replace the furnace prematurely for a properly sized furnace that will deliver better climate control.
- Choosing the right blower. There are 2 or 3 different blower sizes that can go in a 100,000 BTU furnace depending on the home’s ductwork, size and other factors. Getting that wrong might cause both mechanical and comfort issues, and either one could lead to furnace replacement.
- Installation. Basic installation errors are common, unfortunately. Just search “bad furnace installation,” and you’ll get interesting results like this YouTube video and this Slideshow from Contracting Business. A variety of problems from bad installation can cut short furnace lifespan.
How Heavily the Furnace is Used
This is an obvious one.
The same furnace will last much longer in Duluth, Georgia than it will in Duluth, MN when both are correctly installed are maintained.
Whether it Is Cleaned and Maintained
What happens if you don’t clean and maintain your furnace? Here are common issues due to lack of caring for the furnace.
- Filter: The filter gets so dirty that it impedes airflow. Eventually the furnace has to work harder to “breathe,” and this will lead to damage to the blower or overheating which might ruin the control board or other electrical parts.
- Blower: When the blower fan assembly gets very dirty, the same problems can happen, even if you routinely change or clean the filter.
- Balance: Blower motors occasionally need to be balanced. If the blower runs long enough out of balance, damage will occur, and it will need replacing.
- Efficiency: Furnace efficiency suffers when a furnace isn’t maintained, and this often leads homeowners to think the furnace is worn out. They might replace it, when a good cleaning and regular maintenance is all that is needed.
Pro Tip: Your furnace’s warranty requires you to keep it maintained, or your warranty will be voided.
Is that true? Yep. United Technology’s (UTC) warranty is a good example of most. UTC makes Carrier, Bryant, Heil, Arcoaire, Keeprite, Day & Night and more brands – a huge share of the total market.
UTC’s warranty says, “Proof must be supplied that the equipment has been properly maintained over the life of the warranty, i.e., a minimum of onceayear maintenance.”
Did you know? We’ve completed an entire guide on Furnace Tune Ups and Maintenance. It includes information on Maintenance Contracts (Tune Up Plans) from local HVAC companies and our opinion of whether they’re a good idea.
Where the Furnace is Installed
Some basements and crawlspaces are very humid. The humidity will lead to corrosion inside the unit, and that will cause repair issues.
In the worst case, the corrosion will ruin the furnace’s heat exchanger. When that happens, carbon monoxide might leak. When a damaged heat exchanger is diagnosed, the furnace is usually replaced since the repair can cost anywhere from $1,000 to more than $2,000.
The Furnace’s Repair Record
It’s normal to be wary about a furnace once you’ve spent $500+ on a major repair. Replacing it pre-emptively before another big bill comes your way is worth considering.
Sure, the furnace might last another 4-7 years, nobody knows of course. But you also don’t know the cost of repairs in those years. Many homeowners do know they don’t want another costly repair or the furnace to quit on them in the middle of winter’s coldest weather. They replace it before either can happen.
Whether You Decide to Upgrade Efficiency and/or Performance
There are other reasons for pre-emptive furnace replacement. Even if it is running pretty well, some homeowners are tired of:
- High heating bills, and/or
- Poor furnace performance, such as fluctuating temperatures or blasts of barely heated air at the beginning of the cycle
Today’s top furnaces are remarkably efficient. All the brands make models that convert at least 96% of the fueled burned into usable heat for your home.
Consider replacing a 70% furnace with one of those! That’s a 37% increase in efficiency! An efficient gas furnace translates into very real savings on winter heating costs. In other words, you get a good return on your investment from a high-efficiency furnace. The colder your winters are, the sooner you will be repaid for the furnace through lower energy costs.
The best furnaces are also outstanding performers. They have two-stage and variable-capacity heating with a variable-speed fan. The combination produces quiet, even heat that eliminates the chilly blasts.
Would you like to learn more about efficiency and performance? Our Gas Furnace Buying Guide is very comprehensive. It covers every factor to consider – Quality, Performance, Efficiency, Size and more as you plan your furnace purchase.
We’ve completed similar guides for Oil Furnaces and for Electric Furnaces too.
Discuss Your Options with a Pro for Free
Replacing your furnace on your terms rather than when it “decides” to quit on you or give you another winter of expensive heating is worth considering.
Would you like to talk about your options and get written quotes from pre-screened, licensed installers in your area? Use our Free Local Quotes tab and fill out a brief form, or call the free number on the page.
That’s all it takes to find out new furnace options and get competitive cost estimates. There is no obligation for using the free service.