On a modern Slant/Fin boiler without a standing pilot, the igniter is what starts every single burn cycle, so when it fails the boiler typically produces no flame at all and simply locks out after a few attempts.
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Quick answer
Many Slant/Fin boilers built in the last couple of decades use a hot surface igniter or a spark ignition system instead of a continuously burning standing pilot, both aimed at saving gas that would otherwise be spent keeping a pilot lit around the clock. A hot surface igniter is a small ceramic element that glows red-hot briefly at the start of each call for heat, hot enough to ignite the gas the moment the valve opens; a spark igniter instead produces a repeated electrical spark for the same purpose. Either type is a wear item -- the ceramic element cracks with age and thermal cycling, or the electrode gap widens and weakens the spark, and once that happens the boiler simply can't start a fire on its own anymore.
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When the thermostat calls for heat, the control board first energizes the igniter and lets it reach full temperature or begin sparking, then opens the gas valve a moment later so gas reaches an already-ready ignition source rather than an idle one. The control then checks for proven flame within a set window -- if it doesn't see one, it shuts the valve, waits, and tries again, usually for a limited number of attempts before locking out and requiring a manual reset.
This sequencing is why an igniter failure produces such a clean, repeatable symptom: gas never gets a reliable ignition source, so the control simply never confirms flame and eventually gives up, rather than producing anything unstable or intermittent.
That last symptom -- a brief gas smell right before lockout -- is normal in this specific failure pattern since the valve opens for a moment during each ignition attempt before the control shuts it back down for safety. A lingering or strong gas smell at any other time is different and should prompt leaving the home and calling FortisBC.
A technician checks for voltage or current reaching the igniter during an ignition attempt, and separately checks the igniter's resistance against its rated specification with the power off. A hot surface igniter with an open circuit or wildly out-of-range resistance has failed internally even if it looks physically intact. A spark igniter is checked by observing the spark gap and confirming a consistent, visible spark reaches across it.
| Test | Healthy result | Failed result |
|---|---|---|
| Resistance across a hot surface igniter | Within manufacturer's rated range | Open circuit or far outside range |
| Visual glow during ignition attempt | Bright, even orange-red glow | Dim, uneven, or no glow at all |
| Spark igniter gap observation | Consistent visible spark | Weak, intermittent, or no spark |
With power and gas isolated, the old igniter is unbolted from its mounting bracket near the burner and its connector unplugged, taking care not to touch the new ceramic element's surface with bare fingers since skin oils can shorten its life -- a clean cloth or the original packaging is used for handling. The new igniter is positioned at the correct distance and angle from the burner, since placement affects how reliably it lights the gas just as much as the part's condition does.
Once installed, the boiler is cycled through several full ignition attempts to confirm consistent, first-try lighting rather than a marginal pass, since an igniter positioned slightly off can technically work but light unreliably under certain conditions.
Safety note
This is gas-fired combustion equipment working near a live gas supply and, on boilers, a pressurized water loop. Diagnosis and any parts work should be left to a licensed gas fitter -- CANRO holds Technical Safety BC gas licence LGA0043870 and boiler licence LBP0046450. If you ever smell gas, hear hissing at a fitting, or see soot or scorch marks near the burner, leave the home first and call FortisBC at 1-800-663-9911 from outside.
This lockout-after-retries pattern is typical of a failed igniter -- the control keeps trying to establish flame but the ignition source itself isn't working, so it eventually stops attempting for safety.
A brief, faint smell during a failed ignition attempt can be normal since the valve opens momentarily each try, but any strong or lingering gas smell is different and means leaving the home and calling FortisBC.
This involves working directly at the gas burner and verifying safe ignition afterward, so it should be done by a licensed technician rather than as a DIY repair.
Skin oils left on the ceramic element can cause it to fail prematurely once it heats up, so installers handle it with a clean cloth or its original packaging.
There's no fixed schedule since it depends on how many ignition cycles the boiler runs through each season, but they're a normal wear item over the life of the equipment rather than a sign of a bigger problem.
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