Preparing Your HVAC and Ducts for Winter: A Homeowner's Checklist

Furnaces sit dormant for months, then get asked to run 12+ hours a day starting the first cold night. Here is the checklist we use with our maintenance customers to catch problems before they turn into a no-heat 2 a.m. service call.

4 weeks before first frost

• Replace the furnace filter. 1-inch fiberglass filters every quarter; 4-inch pleated media filters annually.
• Run the heat for 20 minutes with the windows open. Burning off dust smells is normal for the first cycle. A smell that persists for more than an hour = call a tech.
• Vacuum every supply register and return grille. Pull the covers off, wipe them down, vacuum the first 12–18 inches you can reach.
• Test every smoke and CO detector. Replace 9V batteries proactively.

2 weeks before first frost

• Book a furnace inspection. Real ones include: heat exchanger inspection, burner cleaning, gas pressure test, CO output test, blower amp draw, static pressure, thermostat calibration.
• Have the ducts scoped if you haven't in 3+ years. Winter is when a dirty system pushes the most contamination back into a closed-up home.
• Clean the dryer vent. Heating season is when a clogged dryer vent is most likely to ignite — the house is drier and the air is warmer.

Week of first frost

• Check every exterior HVAC penetration for animal damage.
• Confirm the outdoor unit is clear of leaves and debris (heat pumps especially).
• Test the furnace at your normal setpoint for a full 60-minute cycle. Listen for banging, whistling, or short cycling.
• Set the thermostat schedule. Setback of 6–8°F overnight saves 8–12% on heating with no comfort loss.

Safety checks that actually matter

• CO detector on every floor, tested and dated
• Combustion air opening to the furnace closet is unobstructed
• Flue pipe joints intact, no visible rust or condensate stains
• No stored items within 3 feet of the furnace cabinet
• Furnace switch (looks like a light switch on the unit) is on — this is the #1 no-heat call in November

What to hire out vs. DIY

DIY: filter, register vacuum, dryer vent lint trap, thermostat schedule, exterior clearance.

Hire out: heat exchanger inspection, burner cleaning, gas pressure, CO test, duct scope, dryer vent full-length clean, humidifier service.

When to book

Best window is 6–8 weeks before your first hard freeze. Waiting until the first cold snap = 4–7 day wait for service and premium emergency pricing. Book early, save money, and start winter with heat that works.

We run winter-prep packages that include furnace inspection, duct scope, and dryer vent cleaning in a single visit. Call our dispatch or book online.