Furnace Maintenance: How Often and What Gets Checked

What It Means

Furnace maintenance is the upkeep that keeps a furnace heating safely and efficiently. Your part is checking the air filter every month during heating season and changing it when it's dirty. A qualified professional should clean and inspect the furnace and its chimney or vent once a year, and ENERGY STAR suggests booking that visit in the fall. On a gas or oil furnace, the inspection covers the fuel connections, the burner and the heat exchanger, and DOE warns that a leaking heat exchanger can let carbon monoxide into the house.

Try It: Walk Through a Year of Furnace Care

Step through a year of furnace care, from booking the fall visit to the safety checks that run all year.

Step 1 of 4

Fall: book the inspection

Have a qualified contractor check the furnace in fall, before the cold (ENERGY STAR). A professional should clean and look over the heating equipment and chimney every year (U.S. Fire Administration).

How It Sounds at Home

"The furnace guy's coming before it gets cold."
"Did anyone change the furnace filter this month?"
"They checked the heat exchanger and it's fine."

The Breakdown

How often. Sources are ENERGY STAR, the U.S. Fire Administration (USFA) and the Department of Energy (DOE).

Job	How often	Who	Source
Check the air filter	Every month, especially in winter	You	ENERGY STAR
Change the filter	When it looks dirty, and at least every 3 months	You	ENERGY STAR
Heating check-up	Every fall	Qualified contractor	ENERGY STAR
Professional cleaning and inspection of the furnace and chimney	Every year	Qualified professional	USFA
Check the vent pipe and chimney for deterioration	At the professional visit	Heating professional	DOE
Test smoke alarms	Every month	You	USFA
Carbon monoxide alarm	Keep a working one in the home	You	DOE

What the fall visit should cover, per ENERGY STAR

Gas or oil connections, gas pressure, burner combustion and the heat exchanger
Moving parts lubricated, which cuts friction in the motors
Controls tested so the furnace starts, runs and shuts off properly
Blower parts cleaned and adjusted for good airflow
Electrical connections tightened

Between visits. With a spare filter on the shelf, a dirty one can be swapped the same day the monthly check finds it. Keep the date of each professional visit, so you know when the next yearly inspection is due.

Good to Know

DOE explains that a worn vent or chimney can leak carbon monoxide and other combustion byproducts into the home, and a leaking heat exchanger can mix combustion gases with the air you breathe. It suggests every home have a working carbon monoxide alarm. ENERGY STAR notes that gas or oil connections that aren't working properly are a fire hazard, which is why they're a job for a qualified contractor.

FAQ

How often should a furnace be serviced?

Once a year. The U.S. Fire Administration calls for a yearly professional cleaning and inspection of heating equipment and chimneys, and ENERGY STAR suggests booking the heating check-up in the fall.

How often should I change my furnace filter?

ENERGY STAR says to check it every month, especially in winter, and change it if it looks dirty. Change it at least every 3 months either way.

Why does a furnace inspection matter for carbon monoxide?

DOE notes that a leaking heat exchanger or a worn vent or chimney can let combustion gases, including carbon monoxide, into the house. The inspection looks for those faults, and DOE also suggests every home have a working carbon monoxide alarm.

Related Terms and Categories

HVAC filter
The removable filter in a furnace, central air conditioner or heat pump that traps dust from the air; ENERGY STAR says check it monthly and change it at least every 3 months.
HVAC tune-up
A service visit where a qualified contractor checks, cleans and adjusts a heating or cooling system; ENERGY STAR advises one for cooling each spring and heating each fall.
Carbon monoxide detector
An alarm that sounds when carbon monoxide, a poisonous gas, builds up to a dangerous level in the air of a home.
Chimney sweep
A professional who inspects and cleans chimneys, fireplaces and vents. NFPA 211 calls for an inspection at least once a year, with cleaning as needed.
Smoke detector testing
Pressing a smoke alarm's test button once a month to make sure it sounds, and replacing the alarm 10 years after the date it was made.
Seasonal home maintenance
Home upkeep sorted by time of year, so each job lands when the weather suits it and before the system it protects is needed most.

Home maintenance and repairs

Sources

ENERGY STAR, "Maintenance Checklist"; U.S. Fire Administration, "Heating Fire Safety"; U.S. Fire Administration, "Smoke Alarms"; U.S. Department of Energy, "Furnaces and Boilers"; U.S. Department of Energy, "Combustion Appliance Safety" tech brief

Last updated September 29, 2026.

Furnace maintenance