How long does a furnace last?

Published July 21, 2026.

A gas furnace typically lasts about 15 to 20 years, and Carrier and Trane both put a well-maintained unit in that range. The US Department of Energy assumes an average residential furnace lifetime of 21 years in its own cost calculations, so a furnace that gets regular care can reach the top of the range or beyond. Electric furnaces usually run longer, often 20 to 30 years, because they have fewer moving parts and no combustion. Your actual number depends on maintenance, how the unit was sized and installed, and how hard it works through your winters.

Furnace lifespan by system type

The three common ways to heat a home age differently, mostly because of how many mechanical and combustion parts each one has.

System type	Typical lifespan	Why
Gas furnace	About 15 to 20 years	Combustion and moving parts wear over time; the DOE assumes about 21 years with good care
Electric furnace	About 20 to 30 years	Fewer mechanical parts and no combustion, so less to fail
Heat pump	About 15 years	Runs year round for both heating and cooling, so it logs more total hours

Carrier gives 15 to 20 years for a well-maintained gas furnace, with excellent care stretching some systems toward 30, and 20 to 30 years for electric furnaces. A heat pump is a different machine, since it heats and cools all year, and the Department of Energy uses an average life of 15 years for one in its efficiency math. If your home has a heat pump instead of a furnace, plan around that shorter figure.

What shortens or extends a furnace’s life

Two identical furnaces can end up years apart depending on how they are cared for and how they were put in. These are the factors that move the number.

Maintenance and filter changes. Trane recommends changing the filter every 30 to 90 days, and notes that a well-maintained furnace lasts longer than one that skips its yearly inspection. Carrier warns that clogged filters restrict air and force the furnace to work harder and longer.
Correct sizing. Carrier notes that an oversized furnace turns on and off rapidly, which stresses parts, while an undersized one must run almost continuously. Both patterns wear a unit out early.
Installation quality. Trane puts it plainly: a furnace is only as good as its installation. A poor install can shorten the life of an otherwise good unit.
Run time and climate. Trane notes that the longer your winters and the harder the furnace works, the shorter the lifespan tends to be. A furnace in a cold northern climate logs more hours than the same unit in a mild one.

Signs your furnace is failing

A furnace usually gives you warning before it quits for good. Trane and Carrier point to these as the main signals, and any one of them is worth a closer look.

Age past 15 years. Once a furnace is in the back half of its expected life, Trane says to pay closer attention, since most repairs cluster in the final years.
Frequent, costlier repairs. Trane flags repairs that get more frequent and more expensive as a top sign the unit is on its way out.
Rising energy bills. A furnace loses efficiency as it ages. Carrier notes that a jump in heating costs with no change in weather points to efficiency loss.
Short cycling. Carrier describes a furnace that turns on and off every few minutes as short cycling, which wastes energy and stresses components.
A yellow burner flame. A healthy gas flame burns blue. Carrier notes that a burner or pilot that burns yellow, or refuses to stay lit, points to a combustion problem.
Strange noises or smells. Carrier calls banging, screeching, or rotten-egg smells red flags that warrant a service call.

Repair or replace

When something breaks, the age of the unit usually decides the call. Carrier’s rule of thumb: if a repair would cost 50 percent or more of a brand-new system and your furnace is nearing the end of its life, replacement is the better investment. Carrier adds that a furnace over 15 years old facing a repair estimate near half the cost of a new unit is a clear candidate for replacement.

A younger furnace with a small, cheaper fix is usually worth repairing. If yours is still in its first several years and needs a minor part, that repair generally makes sense. You can estimate where yours stands with our furnace lifespan calculator.

Gas furnaces burn fuel, and combustion carries real safety stakes. Carrier warns that a cracked heat exchanger can leak carbon monoxide into your home, which is why a yellow flame, a rotten-egg smell, or any CO alarm is an emergency, not a wait-and-see. Confirm any repair-or-replace decision, and any install, with a licensed HVAC professional and your local codes before you act.

Sources

US Department of Energy · Purchasing Energy-Efficient Residential Furnaces. energy.gov/cmei/femp/purchasing-energy-efficient-residential-furnaces
US Department of Energy · Purchasing Energy-Efficient Residential Air-Source Heat Pumps. energy.gov/cmei/femp/purchasing-energy-efficient-residential-air-source-heat-pumps
Carrier · How Long Does a Furnace Last? carrier.com/us/en/residential/hvac-resources/furnaces/how-long-does-a-furnace-last
Carrier · Furnace Repair vs. Replacement: Costs and Decision Guide. carrier.com/us/en/residential/hvac-resources/furnaces/furnace-replacement-cost-vs-furnace-repair-cost
Carrier · Furnace Repair Service, Signs and Troubleshooting. carrier.com/us/en/residential/hvac-resources/furnaces/furnace-repair
Trane · How Long Does a Furnace Last? trane.com/residential/en/resources/blog/how-long-does-a-furnace-last
Trane · 5 Warning Signs It's Time for Furnace Replacement. trane.com/residential/en/resources/blog/furnace-replacement-warning-signs

Furnace lifespan calculator →

Frequently asked questions

How long does an electric furnace or heat pump last compared to gas?

A gas furnace typically lasts about 15 to 20 years, while Carrier notes that electric furnaces often run 20 to 30 years because they have fewer mechanical parts and no combustion. A heat pump, which both heats and cools, tends to be closer to a gas furnace in service life. The US Department of Energy uses an average life of 15 years for a residential air-source heat pump in its cost calculations. In every case, the real number depends on maintenance, sizing, and how hard the unit runs.

What is the 50 percent rule for furnace repair versus replacement?

Carrier's guidance is that if a repair would cost 50 percent or more of a brand-new system and your furnace is nearing the end of its life, replacement is the better call. Age matters too, since a furnace over 15 years old facing a major repair is usually worth replacing rather than fixing. A younger furnace with a minor, cheaper repair is generally worth keeping. Getting a written estimate for both the repair and a new unit lets you run the math before you decide.

What are the first signs a furnace is failing?

Watch for age past 15 years, repairs that get more frequent and more expensive, and a sudden jump in heating bills with no change in weather. Carrier also flags short cycling, where the furnace turns on and off every few minutes, and a burner flame that turns yellow instead of blue. Banging or screeching noises and any rotten-egg smell are red flags worth a service call. A cracked heat exchanger can leak carbon monoxide, so treat combustion warning signs as urgent.