A tankless unit or water heater that clicks repeatedly but never lights is one of the clearest signs of a worn or failed igniter.
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Quick answer
On tankless water heaters and intermittent-ignition storage water heaters, the igniter is what actually starts the burner at the beginning of every hot water demand, most often a spark igniter that fires repeated electrical sparks until combustion is detected, or occasionally a hot-surface element depending on the model. It fails when the electrode wears down, the ignition cable degrades, or the spark gap drifts out of the correct distance for a reliable spark. A licensed CANRO technician checks spark quality and electrode condition before replacing it.
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Most tankless water heaters and many current storage water heaters use intermittent ignition rather than a continuously burning pilot, meaning the igniter only activates at the exact moment a hot water demand is detected. A spark igniter does this by generating repeated high-voltage sparks across a small gap right at the burner, continuing to spark for a few seconds until the accompanying flame rod confirms combustion has started, at which point the board stops sparking and the flame rod takes over monitoring. Because it fires fresh on every single hot water draw rather than staying lit continuously, it goes through far more ignition cycles over a year than a standing pilot ever would.
The spark gap itself matters a great deal -- even a small amount of electrode erosion widening that gap can weaken the spark enough to cause unreliable ignition long before the igniter fails completely.
We inspect the electrode tip for erosion and confirm the spark gap is still within the manufacturer's specified distance, since a gap that's drifted even slightly wider than it should be can weaken the spark enough to cause intermittent rather than total failure. We also check the ignition cable and its connections for cracking, corrosion, or a poor ground, since a sound electrode with a compromised cable can produce the exact same symptoms as a worn electrode.
| Symptom | Likely cause | Next step |
|---|---|---|
| Repeated clicking, no ignition | Worn electrode or excessive spark gap | Inspect electrode and gap, replace igniter |
| Ignition works most of the time, occasionally fails | Marginal spark strength from early electrode wear | Replace igniter before it fails completely |
| Weak or irregular spark visible during inspection | Cracked ignition cable or poor ground connection | Test cable continuity and grounding |
An igniter with a worn electrode has no practical repair -- the gap can't be reliably reset by hand to factory tolerance, so replacement is the standard fix. Where the diagnosis points instead to the ignition cable rather than the electrode itself, that cable can sometimes be replaced on its own without swapping the whole igniter assembly, which is a smaller and less costly repair. Either way we verify reliable ignition across several test cycles rather than a single successful light, since a marginal igniter can sometimes fire correctly once and still fail on the next attempt.
Tankless water heaters and intermittent-ignition storage tanks have become the standard choice across most of Richmond's newer construction, from the townhomes replacing older bungalows in Seafair and Broadmoor to the compact in-suite units common in condo towers along No. 3 Road, and all of them rely on this kind of igniter rather than a continuously burning pilot. Because these units fire on every single hot water draw in an active household, sometimes dozens of times a day, igniter wear tends to be one of the more predictable service items we see on Richmond's tankless-heavy housing stock, showing up as a gradual decline in ignition reliability well before an outright failure. In the handful of remaining older storage water heaters in the city's original postwar homes, ignition systems fire less often and igniter wear tends to be a much slower, less frequent issue by comparison.
Safety note
The igniter is part of the combustion system on a natural-gas-fired appliance, and diagnosing or replacing it requires opening the burner compartment, so this work must be done by a Technical Safety BC licensed gas fitter -- CANRO holds gas licence LGA0043870 and boiler licence LBP0046450. If you smell gas near the appliance, leave the home and call FortisBC at 1-800-663-9911.
That clicking is the igniter attempting to spark, and if it never results in ignition, the electrode has likely worn enough that the spark is too weak to light the burner reliably.
Occasional failures can happen, but a pattern of needing to turn the tap off and on to get hot water usually means the igniter is wearing out and should be inspected before it fails completely.
Not reliably in the field -- once the electrode has eroded enough to widen the gap, replacement is the standard and more dependable fix.
No, they're separate parts working together -- the igniter starts the spark that lights the burner, while the flame rod is a different probe that confirms the flame is burning once it's lit.
It depends heavily on how many ignition cycles the unit goes through, which is driven by household hot water use, so a technician checks the electrode's actual condition rather than assuming a fixed lifespan.
No, this requires opening the burner compartment of a gas appliance, which must be done by a licensed gas fitter.
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