Spokane winter HVAC prep: the October checklist that prevents January emergencies
Every year, the first week we hit 18\u00b0F overnight in Spokane, our phone rings off the hook. Furnaces that worked fine in October suddenly can\u2019t light. Heat pumps that handled October mornings can\u2019t keep up with November cold snaps. Almost every one of these failures was preventable with a 60-minute October service.
Devon R.
Tech Network Manager, NATE-certified · October 12, 2025 · 8 min read
Quick answer
Spokane winter HVAC prep (do this in October): (1) schedule furnace tune-up, (2) replace filter, (3) test thermostat, (4) check carbon monoxide detectors, (5) clear vents and returns, (6) inspect heat pump (if you have one) for proper defrost operation, (7) verify backup heat source works, (8) consider IAQ upgrade for tight envelope, (9) check insulation on refrigerant lines, (10) schedule a service call now, not in January.
- Recommended prep window: September–October (before first cold snap).
- Average furnace tune-up: $129–$240.
- Furnace breakdowns spike 280% in the first cold snap of winter.
Every year we get flooded with no-heat calls the first week temperatures drop below 20\u00b0F. Almost every one of those failures was preventable. Here\u2019s what to do in October to avoid being one of them.
1. Replace the filter (and actually size it correctly)
Most Spokane homes run a 1” fiberglass filter that was installed by the builder. That’s fine for summer. In winter, it’s a problem — the filter clogs faster as the system runs more continuously, and a clogged filter makes the heat exchanger run hot. Hot heat exchangers crack. Cracked heat exchangers mean replacement.
What to do: swap to a 4” MERV-13 media filter cabinet. It has 4–5x the surface area of a 1” filter, so it lasts 6–9 months between changes, and it catches wildfire smoke too. We install these for $349–$649.
2. Test the igniter and flame sensor
These are the two most common gas furnace failures in Spokane. The hot surface igniter costs $189–$349 to replace; a flame sensor cleaning is $129–$189. Either job takes 30–$189 minutes. The cost of NOT doing it: a 11pm Sunday emergency call when it’s 12°F outside.
Quick test: set the thermostat to call for heat, watch the furnace cycle. If you see the inducer motor start, hear a click, then nothing — likely the igniter. If the igniter glows orange but no flame lights within 10 seconds — likely the flame sensor.
3. Check the condensate drain (high-efficiency furnaces only)
If you have a 90%+ AFUE furnace, it produces acidic condensate that drains through a PVC pipe. That pipe gets gunked up with algae and slime over the summer. When it clogs mid-January, the furnace shuts down — usually right when you need it most.
What to do: pour a cup of white vinegar down the drain line, let it sit for 10 minutes, then flush with hot water. If you see standing water in the drain pan, the line is partially clogged. Call us.
4. Verify the thermostat is working correctly
Thermostat batteries die in October. The furnace runs intermittently or short-cycles. Homeowner thinks the furnace is broken, calls for emergency service, tech arrives and the fix is a $4 battery.
What to do: replace thermostat batteries now. While you’re at it, make sure the thermostat isn’t near a heat source (lamp, sunny window, supply register) — it’s the #1 cause of “my furnace won’t turn off” service calls.
5. Schedule the fall furnace service
If you only do ONE thing on this list, schedule the fall furnace service. Our techs run a 32-point inspection that catches the failures above (and many more) before they happen. Cost is $189 for non-members, included free with the maintenance plan.
The math: $189 October service vs $750–$1,800 emergency repair in January + a night without heat + a 2-hour dispatch window during peak season. The maintenance pays for itself every year.
6. Make sure you have a service plan
If your furnace fails in December and you’re not on a maintenance plan, you’re at the bottom of the queue during peak season. Plans cost $229/year and include: 2 visits per year, priority dispatch, waived diagnostic, no after-hours surcharge, 2-year workmanship warranty.
During the first cold snap of the year, plan members get same-day service. Non-members wait 2–3 days. That’s the difference between being warm tonight and breaking out the space heaters.
The October checklist takes about 60 minutes if you do it yourself (steps 1\u20134) or about 90 minutes if you add a fall service (steps 5\u20136). Either way, you\u2019re trading an afternoon in October for a guaranteed warm January.