Furnace checklist: getting ready for heating season
A few minutes of checks each month, a short to-do list every fall, and a yearly tune-up keep your furnace safe and ready for the first cold night.
Updated October 2026 by the Green Core Heating & Air teamGet your furnace ready in September or October, before the first cold night. Put in a fresh filter, test the heat at the thermostat, clear the vents and the area around the furnace, and test your carbon monoxide alarms. Then have a technician do a fall tune-up, which covers the burners, ignition, gas connections and safety controls. During heating season, check the filter every month.
Simple steps that keep your furnace ready
No tools needed. These quick habits help your furnace run safely and catch problems early.
Every month during heating season
5 minutes- Check the air filterHold it up to a light. If you can't see through it, change it. ENERGY STAR says to check monthly, and change it at least every 3 months.
- Test your carbon monoxide alarmsPress the test button. Homes with gas appliances need working CO alarms.
- Keep the area around the furnace clearNo boxes, paint, gas cans or cleaning supplies near a gas furnace or its vent.
Every fall, before the first cold night
About 30 minutes- Put in a fresh filterStart the season clean. Note the size printed on the frame so you have spares on hand.
- Replace the thermostat batteriesIf your thermostat uses them. A dead thermostat is one of the most common no-heat calls.
- Test the heatSwitch to heat and set it a few degrees above room temperature. Warm air should come out within a few minutes.
- Open and clear every vent and returnMove rugs and furniture off floor vents and make sure the big return grille isn't blocked.
- Look at the vent pipe outsideCheck that the flue or vent on the roof or side wall isn't blocked by leaves or a nest. Look, don't climb.
- Notice the first-run smellA light dusty smell for the first few minutes is normal. A smell that lingers, or any gas smell, is not.
What a fall furnace tune-up covers
These checks need tools and training. They're what we do at every furnace tune-up.
- Clean and inspect the burners
- Clean the flame sensor and test the ignition
- Check gas connections and gas pressure
- Inspect the heat exchanger
- Test safety controls and limit switches
- Tighten electrical connections
- Check the blower and lubricate moving parts
- Check the thermostat and the full heating cycle
Call us if you notice
- Yellow or flickering burner flameA healthy gas flame is mostly blue.
- Turns on and off every few minutesShort cycling wears parts and wastes gas.
- Blowing cold air in heat modeOften an ignition or flame sensor problem.
- Banging, squealing or rumblingNew noises usually mean a part is wearing out.
- Some rooms stay coldCan point to ductwork or airflow problems.
- Breaker trips or the furnace won't startDon't keep resetting it. Call us.
Safety first: If you smell gas, leave the house and call PG&E or 911 from outside. If your carbon monoxide alarm sounds, get everyone outside and call 911.
Let us handle the fall tune-up every year
Every plan puts your furnace on our calendar so the tune-up happens before the cold, not after something breaks.
Essential Care
For gas furnace or heat pump systems.
- Fall tune-up before heating season with a 21-point safety and performance inspection
- Filter check, with a heads-up when it's time to replace
- Refrigerant pressure and airflow check
- Reduced diagnostic fee and a repair discount during the plan year
- Priority scheduling ahead of non-members
Comfort Plus
For furnace, AC or heat pump systems.
- A cooling-focused spring visit and a heating-focused fall visit
- Everything in Essential Care
- Standard filter included and installed at each visit
- Outdoor coil cleaned once a year
- No diagnostic fee, a bigger repair discount and a 72-hour scheduling guarantee on work days
Total Comfort
For furnace and AC systems, or heat pumps. Our most complete plan.
- Comprehensive spring and fall tune-ups, inside and out
- Outdoor coil deep-cleaned at both tune-ups
- We bring and swap your filter every quarter
- No diagnostic fee, a repair discount and a 48-hour scheduling guarantee on work days
- An extra year of warranty on repairs, and the plan transfers if you sell your home
Quick answers
When should I get my furnace serviced?
In the fall, before heating season. In the North Bay that's usually September or October.
How often should I change my furnace filter?
Check it every month during heating season. ENERGY STAR recommends changing it at least every 3 months, and more often with pets or dust.
Is a burning smell normal when I first turn on the heat?
A light dusty smell for a few minutes is normal as dust burns off. If it lingers or smells like gas, turn the furnace off and call us.
Do I need a tune-up if my furnace is working fine?
Yes. A tune-up is when we catch a weak part or a safety problem before it leaves you without heat.
Book your fall furnace tune-up
Fall fills up fast. Book now and we'll get your furnace ready before the first cold night.
(707) 988-5858Book a tune-up