Winter Furnace Prep Checklist
Furnaces tend to fail on the first cold night, when every system in the neighborhood starts at once. This checklist takes about 30 minutes and catches most of the small problems early.
Before the first cold snap
- Replace the air filter, or clean it if it's the washable type. A clogged filter is the most common cause of weak heat and short cycling.
- Walk through the house and open every supply vent and return grille. Move furniture, rugs and curtains that block them.
- Set the thermostat to heat, raise it a few degrees above room temperature and confirm the furnace starts within a couple of minutes.
- Replace thermostat batteries if your model uses them.
- Clear the area around the furnace. Nothing stored should touch it, and paint, cleaners and gasoline should be kept well away.
Safety checks
- Test every smoke alarm and carbon monoxide alarm and replace the batteries. Replace alarms that are past the date printed on them.
- Look at the flue pipe leading from the furnace to the outside for gaps, rust or loose joints.
- Check outside that the exhaust and intake vents aren't blocked by snow, leaves or nests.
- If you ever smell gas, leave the house right away, don't use switches or phones inside, and call your gas utility or 911 from outside.
Warning signs to act on
- Banging, squealing or grinding when the blower starts
- The furnace turns on and off every few minutes
- Some rooms stay cold while others are hot
- A yellow or flickering burner flame instead of a steady blue one
- A burning smell that doesn't fade after the first run of the season
When to call a professional
- Anything involving gas lines, the burner, the heat exchanger or electrical parts should be handled by a qualified technician, not by you.
- If the furnace is older and repairs are becoming frequent, ask the technician to explain the repair-versus-replace options.
Frequently asked questions
How often should I change the furnace filter?
Check it monthly during heating season. Most one-inch filters need replacing every one to three months, sooner with pets or dust.
Can I tune up the furnace myself?
You can handle filters, vents and thermostat checks. Work on gas, burners and electrical parts is for a qualified technician.
Why does my furnace smell when I first turn it on?
A light dusty smell for a short time is common after months of sitting idle. A strong or lasting burning smell is a reason to turn it off and have it checked.
LocalRepairLine is a referral service, not a contractor. If you want help with any of the above, you can reach an independent local professional through this site.
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