How long does a furnace last?
A furnace typically lasts 15 to 22 years. The home builders’ survey gives 15 to 20 years, and the US Department of Energy’s analysis uses an average of 21.5 years for gas furnaces.
What the published figures say
| Years | Source | What the figure is |
|---|---|---|
| 15 to 20 | NAHB and Bank of America Home Equity, Study of Life Expectancy of Home Components (2007) | From the study’s heating and cooling table. |
| 18 for gas, 20 for oil, 15 for electric | NAHB and Bank of America Home Equity, Study of Life Expectancy of Home Components (2007) | Survey of manufacturers and trade groups. Its appliance figures describe use by the first owner. |
| 21.5 | US Department of Energy, energy conservation standards for consumer furnaces, final rule (2023) | Average lifetime of gas furnaces in the Department’s cost analysis: 22.5 years in the North, 20.2 elsewhere. |
| More than 15: consider replacing | ENERGY STAR, when is it time to replace heating and cooling equipment? | A prompt to weigh replacement, not a life expectancy. |
The sources measure different things, which is why they differ. A survey of first owners gives a shorter figure than an analysis that follows units until they are scrapped. All of them describe typical equipment. A given unit can fail sooner or run far longer, and age alone is not a reason to replace anything that works safely.
How old is yours?
The build date is coded into the serial number. Where to find it: How old is my furnace?
Find the age from the serial number
What the build year tells you
- Built before January 1, 1992, when the first federal minimum for furnace efficiency, 78% AFUE, took effect.
- Built when the federal minimum for furnace efficiency was 78% AFUE. The minimum for gas furnaces rose to 80% on November 19, 2015.
What shortens or extends its life
- Short cycling. An oversized furnace heats the house in short bursts, and every start stresses the heat exchanger and the igniter.
- Restricted airflow. A clogged filter or undersized ducts make the heat exchanger run hot.
- Maintenance that is skipped. A yearly check finds a failing part before it damages others.
Signs that replacement is near
- A cracked heat exchanger. It can let combustion gases into the air of the house and is a reason to replace the furnace, not repair it.
- Repairs that are becoming frequent, or one repair that costs a large share of a new furnace.
- Higher fuel use for the same weather.
- Rooms that no longer heat evenly, or a furnace that runs almost without stopping in ordinary cold.
- Yellow or flickering burner flames, or soot around the furnace. Have it checked promptly. If a carbon monoxide alarm sounds, leave the house and call the gas utility or 911.
Sizing the replacement
Sources
- NAHB and Bank of America Home Equity, Study of Life Expectancy of Home Components (2007): https://teamcomplete.com/wp-content/uploads/2015/12/07-NAHB-Life-Expectancy-Depreciation-Feb-2007.pdf
- US Department of Energy, energy conservation standards for consumer furnaces, final rule (2023): https://www.govinfo.gov/content/pkg/FR-2023-12-18/html/2023-25514.htm
- ENERGY STAR, when is it time to replace heating and cooling equipment?: https://www.energystar.gov/saveathome/heating-cooling/replace
- Code of Federal Regulations, 10 CFR 430.32, energy and water conservation standards: https://www.ecfr.gov/current/title-10/section-430.32
Other equipment
- How long does a water heater last?
- How long does a tankless water heater last?
- How long does a central air conditioner last?
- How long does a heat pump last?
- How long does a refrigerator last?
- How long does a washing machine last?
- How long does a clothes dryer last?
- How long does a dishwasher last?
- How long does a range or oven last?
Figures last checked against their sources on October 5, 2026. Method and sources.