A furnace that won't light almost always comes down to one of four parts: the ignitor, the flame sensor, the gas valve, or the control board. The first two are cheap, fast, and usually a same-visit fix. The last two are where the quote gets uncomfortable and where homeowners in Federal Way, Kent, Puyallup, and Olympia start asking a fair question — am I fixing this furnace, or feeding it?
Here's the honest version, with real ranges and the diagnostic logic behind them.
Two parts, two very different failures
The gas valve
The gas valve is the gatekeeper. It sits between the gas line and the burners, opens only when the control board tells it to, meters fuel at a specific manifold pressure, and shuts off the instant a safety upstream says stop. It is a safety device first and a performance part second.
When a valve fails, you usually see one of three things: the ignitor glows and nothing lights, the burners light and drop out immediately, or the furnace lights only sometimes. Valve failures are less common than board failures, but they are also the ones you never improvise around.
The control board
The integrated furnace control board is the brain. It runs the whole ignition sequence in order — inducer motor on, pressure switch proves draft, ignitor warms, gas valve opens, flame sensor confirms a flame, blower starts after a timed delay — and it shuts everything down if any step fails.
Board symptoms look different: no response at all when the thermostat calls, a blinking fault code behind the sight glass, a blower that runs nonstop, or intermittent lockouts that clear when you cycle the breaker and come back a week later.
From the hallway, a dead valve and a dead board look identical. Both read as "no heat." Only a meter and a sequence test tell them apart, which is exactly why the diagnostic matters more than the part.
What these repairs cost in Washington in 2026
Typical furnace repair in standard Puget Sound markets runs $150 to $1,500, and $175 to $1,800 in affluent markets like Seattle, Maple Valley, Normandy Park, Black Diamond, Steilacoom, and Fircrest. Gas valves and control boards both live inside that band — they just sit at different points in it.
| Repair | Where it lands in the typical range |
|---|---|
| RepairFlame sensor cleaning or ignitor | Where it lands in the typical rangeBottom of the range |
| RepairPressure switch or limit switch | Where it lands in the typical rangeLower middle |
| RepairGas valve replacement | Where it lands in the typical rangeMiddle of the range |
| RepairControl board replacement | Where it lands in the typical rangeUpper half of the range |
| RepairBoard plus valve on a 15+ year furnace | Where it lands in the typical rangeTop of the range, and a replacement conversation |
Four things move the number within that band:
- Part specificity. Integrated furnace controls are model-matched. There is no generic board.
- Age and availability. Parts for a 2008 furnace may be a special order rather than a shelf item.
- Access. A tight closet or a low crawl space adds labor a garage install doesn't.
- Collateral damage. If the failure took out a transformer or scorched a wiring harness, that's more work.
The expensive mistake — replacing the part without finding the cause
Control boards rarely die of old age by themselves. They die because something else killed them. The usual suspects we find in Puget Sound homes:
- A shorted or pinched low-voltage thermostat wire
- A failing inducer or blower motor pulling more current than the relay is rated for
- A grounded or failing transformer
- Water intrusion from a condensate line, a rusted flue, or a damp crawl space
- Rodent damage to the harness, which is far more common out in Graham, Enumclaw, and Yelm than most people expect
Swap the board, skip the cause, and the new board fails too. That's a second invoice for the same problem, and it is the single most common reason a homeowner calls us for a second opinion.
Gas valves have their own version of this. A valve that fails after years of short-cycling or repeated ignition lockouts is telling you something about airflow, the flue, or a filter that was never changed. Fix the pattern, not just the part.
Puget Sound specifics that change the math
Our mild marine climate is easy on furnaces. Fewer run hours, fewer ignition cycles, less thermal stress. That cuts both ways: a control board failing at eight years old in Western Washington usually means an underlying electrical or moisture problem, not normal wear.
What is hard on equipment here is moisture. Furnaces in unconditioned crawl spaces, detached garages, and damp basements corrode faster than the same unit installed in a dry utility closet. Corroded terminals and damp boards are a Puget Sound signature failure.
One more practical note: a component repair isn't a permitted job. A full furnace replacement is, in every one of the 45 cities we serve, and we pull it on every install.
Repair or replace — the line we actually use
- Under 15 years old and the repair costs less than half a new system. Fix it. A board or valve on a healthy 10-year-old furnace is a good buy.
- 15+ years old with a four-figure quote. Price replacement before you authorize anything.
- Repeat repairs two winters running. You're buying time, not value, and none of it comes with a warranty.
- Any sign of a cracked heat exchanger. That's a safety shutdown, not a repair line item.
Replacement numbers for comparison: gas furnace replacement runs $4,000 to $8,000 installed in standard markets and $5,000 to $10,000 in affluent markets. Furnace and central AC together runs $10,000 to $16,000. A ducted heat pump, which covers heating and cooling in one system, runs $12,000 to $18,000 standard and $13,800 to $24,300 in affluent and luxury markets.
That last row matters because the heat pump is the only path that can qualify for local utility rebate money when it replaces an existing electric or fossil-fuel system, with the amount depending on what you're replacing and what you install. Two things worth knowing: the federal 25C tax credit ended December 31, 2025, so no 2026 install qualifies, and utility rebate programs pay only through their own contractor networks and change their rules, so we confirm what your utility actually pays before we quote and handle the paperwork. Rebates also follow the meter, not the county — Tacoma, Fircrest, University Place, and Fife are Tacoma Power, and we check your utility before quoting any incentive.
If you want to see where replacement pricing lands for your home before anyone knocks on your door, the instant estimate tool gives you Good, Better, and Best starting prices in about 60 seconds. For the full trade-off between staying on gas and switching, read heat pump vs. gas furnace in Western Washington.
What you should expect from the repair quote
A good diagnostic tells you three things: which part failed, why it failed, and what the rest of the furnace looks like. If a quote hands you a part number and a price with no explanation of the cause, ask the question directly. On a 20-year-old furnace, ask what the heat exchanger looks like too.
We'd rather tell you the truth about a tired furnace than sell you a board that outlives the equipment it's bolted to. Every installation we do carries a 10-year parts and labor warranty, and most furnace replacements are finished in one day.
No heat right now? Call (253) 785-4622 or request a visit online. Mon–Fri, 8–6, same-week scheduling across King, Pierce, and Thurston counties.