September Home Maintenance Checklist: Heating Starts on Paper

September's list is about heat you won't need for weeks: get the furnace tune-up done (or booked), flush the water heater, inspect the flue pipe, and clean the dryer vent. Then use the mild weather for sealing work that can't happen in the cold: exterior caulk, weatherstripping, and pipe insulation. Add a 15-minute downspout check and a look at the washing machine hoses and you've covered the month. Most of it is DIY; the whole slate is a weekend of work plus one professional visit.

Our fall maintenance guide walks the entire season. This page is narrower: what belongs on the calendar in September, before October's leaves and first frosts change the job.

Get the heating system serviced before you need it

If you booked ahead in August, your appointment lands this month. If not, call today; every week of delay puts you deeper into the post-first-cold-night rush.

The fall tune-up is a professional job on gas and propane furnaces: the technician inspects the heat exchanger for cracks, checks gas connections, calibrates the thermostat, and tests the safety controls. Expect $100–200 for a 2–3 hour visit. Skipping it risks a mid-January breakdown, a voided warranty, and, worse, a cracked heat exchanger quietly leaking carbon monoxide into your ductwork.

Timing shifts with climate. In cold zones 5–7 aim for early September; Minneapolis can see frost before the month ends. In hot-humid zones 1–2 the AC is still doing the heavy lifting, and the heating visit can slide to October.

While you wait for the pro, do the one heating check that's free: follow the flue pipe from your furnace or boiler to the chimney or wall exit, looking for corrosion, gaps at the joints, or soot stains. Fifteen minutes, and rated critical for a reason: a disconnected flue dumps carbon monoxide straight into the house. Anything suspicious gets a professional look, typically $75–200.

Fireplace owners, same logic. The chimney sweep ($150–350) and the gas fireplace inspection ($100–250) both belong before burning season, and September calendars still have room.

Flush the water heater — 30 minutes, almost free

This is the highest-value DIY task of the month, and almost nobody does it. Sediment settling at the bottom of a tank water heater cuts efficiency by 20–40% and can shorten a 12-year tank's life to 6–8 years. The annual service has four parts:

1. Confirm the thermostat reads 120°F. Hotter wastes energy and risks scalding; cooler invites bacteria.
2. Set the gas control to pilot (breaker off for electric), attach a garden hose to the drain valve, and drain 2–3 gallons until the water runs clear.
3. Look over the fittings and the base for rust streaks, corrosion, or dampness.
4. Test the temperature-pressure relief valve: bucket underneath, lift the lever briefly, confirm water flows and stops. That valve is what stands between a failing tank and a burst one.

Budget 30–45 minutes and under $5 in supplies, or $100–200 for a plumber. Gas units get one extra check: make sure the vent pipe is intact and the burner area has clear airflow.

Tankless owners aren't exempt; the equivalent job is a 45–60 minute descaling flush, circulating white vinegar through the unit with a pump kit ($20–40 DIY, $150–300 professionally). Scale can halve a tankless unit's 20-year lifespan. Both types are covered in our water heater maintenance guide.

Clean the dryer vent, not just the lint trap

Lint-clogged vents are the leading cause of home dryer fires, about 2,900 per year in the US. The lint trap you clear every load only catches part of the problem; the duct behind the dryer collects the rest.

Pull the dryer out, disconnect the duct, and brush it clean from the dryer connection to the exterior outlet. Check for kinks or crushed sections, and confirm the outside flap opens freely and isn't hosting a bird's nest. Any plastic or foil duct in the run should become rigid metal; the flexible stuff is a fire hazard. Plan on 30–60 minutes and up to $30 for a brush kit, or $100–200 for a professional cleaning. A clogged vent also roughly doubles drying energy use, so this pays for itself even without the fire math.

Seal the envelope while caulk can still cure

Sealant work needs mild, dry weather, and September is usually the last reliable stretch of it in the northern half of the country. Three jobs, all easy:

• Refresh exterior caulk. Work around windows, doors, trim, and every joint where two materials meet. Dig out anything cracked or peeling and reapply exterior-grade silicone or polyurethane. It's 1–2 hours and $10–30 in materials ($150–400 hired out). Failed caulk lets water into the walls, where it rots framing invisibly, and the air leaks alone can raise energy bills 10–20%. In zones 5 and up, freeze-thaw cycles chew through caulk fast enough that this becomes a twice-a-year check.
• Replace worn weatherstripping. Focus on interior doors between heated and unheated spaces: the garage entry, attic hatch, basement door. Compressed or torn strips take 15–30 minutes and $10–30 to swap. A leaky garage door also lets exhaust fumes migrate indoors, so this is more than a comfort fix.
• Check pipe insulation. Walk the basement, crawl space, garage, and attic looking for bare or damaged insulation on water pipes, and add foam sleeves to the first several feet of hot water line off the water heater. Count on 30–60 minutes and $10–50. This is high priority in zone 5 and critical from zone 6 north; an uninsulated pipe in a Duluth crawl space is a burst pipe waiting for the first hard freeze.

Point water away from the foundation

Full gutter cleaning waits until the leaves actually drop (that's an October job), but two drainage checks belong in September.

First, downspout extensions: 15 minutes to confirm every downspout discharges 4–6 feet from the foundation, and $5–20 to reattach the ones that have wandered. Water dumped at the foundation line causes the settling and cracking behind repair bills that average $5,000–15,000.

Second, in the hot-dry West, September is still peak fire season. Clearing dry leaves and pine needles from roof valleys and gutters removes the fuel that wind-blown embers land on. An hour or two DIY from a stable ladder; anything you can't reach from the ladder or a low-pitch roof is worth the $100–300 crew.

Two ten-minute checks worth the calendar space

Washing machine hoses fail without warning, and a burst hose is the single most common source of residential water damage claims, releasing 500-plus gallons an hour. Check the supply hoses for bulges, cracks, or rust at the fittings, and swap any rubber hose older than five years for braided stainless steel ($15–40, ten minutes).

Sump pump owners who skipped the August test: pour a five-gallon bucket of water into the pit and confirm the pump runs and shuts off. Free, and it beats finding out during a nor'easter.

If you have a pool or a septic system

Pool owners in zones 3 and colder should close before the first freeze, which in zones 5–7 can mean late September rather than October. It's a 2–4 hour job ($100–250 DIY, $200–500 for a service), rated critical because frozen pool plumbing runs $1,000–3,000 to repair. Year-round pools in zones 1–2 skip it entirely.

Septic owners due for a pump-out should book now, while the ground is dry. The inspection and pump runs $300–600; a neglected system that saturates its drain field costs $10,000–30,000 to replace.

Common questions

Is it too late to book a furnace tune-up in September?

No, but don't sit on it. Early September calls usually land an appointment within a couple of weeks; by mid-October you're waiting behind everyone whose furnace didn't start on the first cold morning.

Can I really flush the water heater myself?

Yes, if you can attach a garden hose to a valve. Turn the gas control to pilot first — or kill the breaker on an electric unit — then drain 2–3 gallons until the water runs clear; there's no need to empty the whole tank. One caution: a drain valve that hasn't moved in years can refuse to reseal, so keep a hose cap handy.

Should I clean the gutters now or wait for the leaves?

Wait, unless you're in wildfire country. The drainage cleaning is an October or November job, done after most leaves are down. The exception is fire fuel: dry needles and roof debris should come off now in the hot-dry West.

What's the one task I shouldn't skip this month?

The dryer vent, if forced to pick. It's rated critical in our rules data, the failure mode is a house fire, and the fix is an hour with a $20 brush. The water heater flush is a close second.

The right September list depends on the house: no chimney means there's no sweep to book, city sewer means the pump-out paragraph isn't yours, and a zone 2A homeowner can push the heating visit a month. SeasonKeep sorts out which tasks your zip code, build year, and systems actually get, free to start. When this month's boxes are checked, the October checklist picks up where the leaves come down.