How Long Does a Furnace Last? 15 to 30 Years, New $2,823+

Lifespans assume yearly maintenance. ENERGY STAR says to consider replacing a furnace or boiler once it is more than 15 years old.

Do this now: an old furnace quits in freezing weather

If an old furnace stops heating in cold weather, deal with safety first, then the simple checks, then the pipes.

1. Smell gas? Leave now. Do not touch light switches, the thermostat or appliance controls. From outside, call 911 and the gas utility (Southwest Gas).
2. CO alarm sounding? Do not look for the source. Get everyone outside, call 911, and stay out until responders say it is safe (CPSC).
3. Check the thermostat. Set it to HEAT, above room temperature, with the fan on AUTO. Lennox says battery thermostats can act up on low batteries, so put in new ones.
4. Check the filter and the breaker. A clogged filter can make the furnace overheat and shut off (Lennox). Bryant says not to keep resetting a breaker that trips again.
5. Protect the pipes while you wait. Open kitchen and bathroom sink cabinet doors and let cold water drip from faucets on exposed pipes (American Red Cross). Keep space heaters at least 3 feet from drapes, furniture and bedding, and never heat the house with the stove, a grill or a generator (CDC).

Is it urgent? When an old furnace needs a call today

An old furnace needs a same-day call when you smell gas, a CO alarm goes off, you see soot, or the house has no heat in freezing weather. Rising bills and odd noises can wait for a weekday visit.

• Soot around the furnace: Carrier says to turn the system off and call a professional.
• A yellow flame instead of blue: Lennox says a yellow flame base suggests a blockage. Have it checked before you keep running it.
• A breaker that trips again after a reset: leave it off and call (Bryant).
• No heat in freezing weather: the Red Cross says to keep the heat no lower than 55 F when you are away, because pipes can freeze. See frozen pipes if water stops flowing.

After-hours furnace work costs more: HomeGuide puts emergency labor at $140 to $210 an hour. See emergency HVAC repair for what to do before the technician arrives, and CO alarm going off if an alarm is sounding.

How long does a gas furnace last

A gas furnace lasts 15 to 25 years with regular maintenance, according to HomeAdvisor's 2026 guide and HomeGuide. Lennox gives a shorter 15 to 20 years, and Bryant says most furnaces last around 15 to 20. HomeAdvisor lists an age over 15 years as a sign to start thinking about a replacement. Lennox says a furnace with yearly maintenance should last well over 15 years, and that you can find the age in the owner's manual or from the serial number on the unit.

How long does an electric furnace last

An electric furnace lasts 20 to 30 years, says HomeGuide's 2026 guide, about five years longer than a gas furnace; Lennox gives the same 20 to 30 years. The trade-off is running cost: HomeGuide says an electric furnace costs 2 to 4 times as much to run as gas, and that a heat pump uses about 50% of the electricity an electric furnace does. HomeGuide puts electric furnace replacement at $1,900 to $5,600 installed.

How long does an oil furnace last

An oil furnace lasts 15 to 25 years, according to HomeGuide's 2026 oil furnace guide, and some last more than 30 years when they are sized right, installed well and serviced every year. The two big guides price replacement very differently: HomeGuide puts an oil furnace at $2,500 to $6,000 on average, while HomeAdvisor's 2026 range is $6,750 to $10,000 or more. Get more than one quote.

How long do heat pumps and boilers last

A heat pump lasts about 14 years on average in HomeAdvisor's 2026 data, with newer units reaching 20 or more; Lennox says about 15 years. ENERGY STAR's replacement mark for heat pumps is 10 years, not 15. A boiler lasts 15 to 20 years in HomeAdvisor's figures and 15 to 30 in Lennox's. Problems with either are covered in heat pump repair and boiler repair.

Should I replace a 20-year-old furnace? Repair or replace rules

A 20-year-old furnace is past the 15-year mark ENERGY STAR uses, so price a replacement before you approve any big repair. HomeGuide says replacement is usually the better choice for furnaces older than 20 years or needing frequent repairs. These are the rules the guides use:

Bryant says to pair the $5,000 rule with a professional evaluation, not to rely on age alone.

The $5,000 rule in practice: CBS News gives the example of a 12-year-old system with a $500 repair, which gives $6,000 and points to replacement, and a 7-year-old system with a $400 repair, which gives $2,800 and points to repair. For scale, HomeAdvisor puts the average furnace repair at $318 in 2026 and a new furnace at $2,823 to $6,897 installed. See furnace repair costs for part prices.

Signs your furnace is failing

The clearest sign a furnace is failing is repeat repairs combined with rising energy bills, which both ENERGY STAR and Lennox list. Other signs:

• Some rooms too hot or too cold, humidity problems, excess dust or a noisy system (ENERGY STAR).
• Slow startup or new, louder noises (Lennox).
• Several repairs within a few years (Lennox).
• Cold air from the vents while the heat is on: see furnace blowing cold air for the causes and what is safe to check.
• A cracked heat exchanger found on a service visit. HomeGuide puts the repair at $1,000 to $3,000 and says most technicians replace the furnace instead.

How much does it cost to replace a furnace

Replacing a furnace costs $2,823 to $6,897 installed in HomeAdvisor's 2026 data, and most homeowners spend about $4,814. HomeAdvisor puts gas furnaces at $3,800 to $10,000 and electric at $2,000 to $7,000; HomeGuide puts an installed gas furnace at $3,800 to $12,000. ENERGY STAR says a certified furnace is 15% more efficient than a conventional one. The IRS says the federal 25C credit does not apply to anything placed in service after December 31, 2025, so no federal tax credit applies in 2026. Full price tables are in furnace replacement cost, and the electric alternative in heat pump installation cost.

How to make a furnace last longer

• Yearly service. CPSC says to have the heating system professionally inspected and serviced every year. HomeAdvisor puts a furnace tune-up at $125 to $200.
• Filters. Lennox says clogged filters make the furnace work harder, and to replace them usually every three months.
• Right size at install. The DOE says contractors should size equipment with ACCA Manual J, and that maintenance can cut heating and cooling costs by 10% or more.

Ask the company for its license number and proof of insurance; the HVAC license table lists who issues licenses in six states. More heating guides are on the HVAC repair hub, and every trade's prices are in home repair costs. Calls go to an independent company that serves your area and takes this kind of job. How calls work.