How to Prepare Your Furnace for Winter in Marion, OH

September 12, 2026 · 6 min read

Marion winters don't ease in gradually. One week it's 55°F, the next your furnace is running around the clock to keep up with single-digit wind chills. The time to prepare is before the first cold snap — not during it, when every HVAC company in Marion County is booked solid.

Here's the checklist we give our own maintenance members, straight from the technicians at PJ's.

1. Replace Your Air Filter

This is the single most impactful thing a homeowner can do. A clogged filter restricts airflow, forces your furnace to work harder, and can trigger a safety shutdown. Check it monthly; replace it every 1–3 months depending on the type. If you have pets, lean toward monthly.

2. Test Your Thermostat

Switch to HEAT mode and set the temperature 5 degrees above room temp. You should hear the furnace kick on within a minute or two and feel warm air at the registers within five. If nothing happens, check the batteries (if battery-powered) and make sure the breaker is on. A programmable or smart thermostat can save 10–15% on heating bills by lowering the temp while you're away or asleep.

3. Clear the Area Around Your Furnace

Your furnace needs clearance for airflow and safe operation. Move boxes, paint cans, laundry supplies, and anything flammable at least 3 feet away from the unit. This isn't just efficiency — it's a fire safety requirement.

4. Check Your Vents and Registers

Walk through every room. Make sure supply and return vents are open and unblocked by furniture, rugs, or curtains. Closing vents in unused rooms is a common myth — it actually increases pressure in the ducts and makes your system less efficient, not more.

5. Inspect Your Exhaust Flue and CO Detectors

If you have a gas furnace, visually inspect the exhaust flue (the metal pipe that vents combustion gases outside). Look for rust, gaps, or disconnections. Then test every carbon monoxide detector in your home — replace batteries and any unit older than 5–7 years. Carbon monoxide is odorless and invisible; a working detector is non-negotiable.

6. Schedule a Professional Tune-Up

A fall furnace tune-up covers everything you can't do yourself: inspecting the heat exchanger for cracks, testing gas pressure and safety controls, measuring airflow, cleaning the burner assembly, and verifying ignition. It typically takes about an hour and can catch small problems before they become mid-January emergencies.

At PJ's, we recommend scheduling your tune-up in September or early October — before the rush. Our maintenance plan members get priority scheduling, no overtime rates, and discounts on repairs.

When to Replace Instead of Repair

If your furnace is over 15–20 years old, needs frequent repairs, or your energy bills keep climbing despite maintenance, it may be time for a new system. Modern high-efficiency furnaces (95–98% AFUE) can cut heating costs by 20–30% compared to an older 80% unit. We offer flexible financing to make the upgrade affordable.