Sacramento winters are mild, which is exactly why heating systems get ignored. A furnace sits idle for seven months, then has to run reliably on the first foggy 35 degree morning. A few small checks in late October or early November catch most of the problems that turn into no-heat calls.
This is the checklist we would follow in our own homes. Every step is something you can do yourself in under an hour, plus one that is better left to a technician.
The five checks to do this week
- Replace the air filter. The Department of Energy advises cleaning or changing filters about once a month while the system is running. A clogged filter restricts airflow, and Carrier notes that restricted airflow can overheat a heat exchanger. If you are not sure which size you need, read our guide to air filter sizes and MERV ratings.
- Test the thermostat. Set it to Heat and raise the setpoint a few degrees above the room temperature. Put in fresh batteries if it uses them. If the screen is blank or the system does not respond, see thermostat not working.
- Test every carbon monoxide alarm. The CDC suggests checking alarm batteries when you change your clocks. In 2026 the clocks go back on Sunday, November 1, which makes a convenient reminder. Also check the date on the alarm itself, because alarms wear out and the CDC advises replacing them on the manufacturer’s schedule or about every five years.
- Clear the space around vents and the outdoor unit. Move furniture and rugs off supply and return vents. If you have a heat pump, clear leaves and debris from around the outdoor unit so air can move through it.
- Run the heat for ten to fifteen minutes. Do it on a mild afternoon, not on the coldest night, so any problem shows up while you still have time to book a repair.
The first-start smell: what is normal
When a furnace runs for the first time after months idle, dust that settled on the heat exchanger and burners burns off. That produces a warm, dusty or slightly burnt smell. Manufacturers give different time frames for how long it should last:
- Trane: about 10 to 15 minutes. If it persists or gets worse, turn the unit off and call a professional.
- Lennox: run the furnace for one to two hours and the smell should fade.
- Carrier: roughly 30 minutes to a few hours. A longer or stronger smell should be investigated.
Burning plastic, an electrical smell or anything like rotten eggs is not normal. If you smell gas, leave the building, call 911, then call your gas utility. PG&E’s gas emergency line is 1-800-743-5000. Do not use light switches, phones or flashlights inside until the area is clear. For more on smells, see furnace smells like burning or gas: what to do.
What a professional tune-up checks
The Department of Energy recommends yearly professional maintenance for a furnace or heat pump, and its home heating guide estimates that regular maintenance can trim heating and cooling costs by around 10 percent. A proper furnace tune-up includes:
- Inspecting the heat exchanger for cracks or leaks
- Checking the burners, the flue and the venting for proper draft and gas spillage
- Testing for carbon monoxide at the appliance
- Checking safety controls and the thermostat
- Checking the blower and the filter
Ask for a written list of what was checked. Our guide to what a tune-up includes and what it costs shows what to expect, and our maintenance service page covers the visit itself.
If the furnace will not start
Most no-heat problems come down to a short list: the thermostat, the furnace power switch and breaker, the filter and the gas shutoff valve. Work through them in order before you call anyone. Our guides cover the common cases:
If a tripped breaker comes back after one reset, or the furnace shuts off again within minutes, stop and book a visit. Repeated resetting hides the real cause.
Heat pump and ductless owners
Heat pumps and ductless systems also run in winter, and they use the same filter and clearance rules. Heat pumps do not need a pilot light check, but they do need a yearly inspection. We cover the details in how often a heat pump needs service and, for ductless units, how to clean a mini split.
We service furnaces and heat pumps across Roseville, Rocklin, Folsom and Elk Grove. Read about our heating and furnace services or request a visit. If your system has already failed, we answer emergency calls 24/7, including weekends.
Frequently asked questions
When should I get my furnace serviced in Sacramento?
Fall, before the first cold week. November is a good target, because heating technicians are still easy to book and any part that needs ordering arrives before you depend on the heat every day. The Department of Energy recommends professional maintenance for a furnace or heat pump once a year.
Is it normal for a furnace to smell the first time I turn it on?
A short burning-dust smell is normal after months of sitting idle. Manufacturers give different time frames: Trane says about 10 to 15 minutes, Lennox says run it for an hour or two, and Carrier says 30 minutes to a few hours. A burning plastic, electrical or rotten-egg smell is not normal.
How often should I change my furnace filter?
Check it every month during heating season and replace it when it looks gray and clogged. The Department of Energy advises cleaning or changing filters about once a month. Homes with pets or dust may need it more often.
What should I do if my carbon monoxide alarm goes off?
Get everyone outside into fresh air, call 911, and do not go back in until responders say it is safe. A single chirp every minute or so usually means a low battery rather than carbon monoxide.
Do I need to prepare a heat pump for winter too?
Yes. A heat pump runs in both seasons, so it needs a clean filter, clear space around the outdoor unit and a yearly inspection like a furnace does. See our guide on how often a heat pump needs service.