A stuck or fouled flow sensor keeps a Burnaby tankless unit from recognizing a hot-water draw at all, and replacing it is a routine tankless repair.
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Quick answer
Replacing a flow sensor on a Burnaby gas tankless water heater is a tankless repair typically priced $250 to $900, with the $90 to $150 diagnostic visit on top. That range reflects 2026 public market data as a ballpark only — CANRO's office and its certified gas technicians confirm the exact cost after they've assessed the specific installation. Because a flow sensor issue can look identical to a low-water-pressure problem from the outside, the diagnostic step matters as much as the part itself.
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A tankless unit only fires the burner once it detects a minimum flow of water moving through it, and the flow sensor — usually a small turbine or paddle wheel wired to the control board — is what makes that call. Open a tap, water moves the turbine, the board sees the signal, and ignition proceeds. Below the minimum flow threshold, or with no signal at all, the unit simply won't light, which is a deliberate design choice, not a fault.
Sediment and fine mineral particles moving through the incoming water line are the usual culprits when this part fails — they can jam the tiny turbine wheel, coat it enough to slow its spin, or lodge in the sensor housing itself. Since it's a moving mechanical part sitting directly in the water path, it's more exposed to whatever comes through the supply line than most other tankless components.
Flow sensor work is a mid-range tankless repair, priced by the same typical-repair line as most electronic and mechanical component faults on the unit.
| Item | Typical cost |
|---|---|
| Diagnostic / service call | $90–$150 (often credited toward the repair) |
| Licensed labour rate | $95–$165 per hour |
| Typical flow sensor repair, parts and labour | $250–$900 |
Whether the fix is a cleaning or a full replacement changes where in the range the job lands — a turbine that's just gummed up can sometimes be freed and cleaned, while one with a cracked housing or worn bearing needs a new part outright. Incoming water quality plays a role too, and homes with an older galvanized supply line feeding the unit can shed more sediment into the sensor over time than a newer copper or PEX line would.
This is also a good moment for CANRO to check the inlet filter screen at the same time, since the two parts sit right next to each other in the water path and a clogged filter often produces very similar symptoms to a failing flow sensor — bundling the check saves a return visit if both need attention.
A repair in essentially every case. The flow sensor is a small mechanical part with no bearing on the rest of the unit's health, so replacing it fully resolves the issue without any broader implications for the appliance's remaining service life.
Safety note
This job does not normally involve any gas-line work itself, but it lives inside a gas-fired appliance, so only a Technical Safety BC licensed gas fitter should open the burner or gas train. If you ever smell gas, hear a hard bang on ignition, or see soot around the appliance, leave the house and call FortisBC at 1-800-663-9911 before doing anything else.
A technician can confirm with a flow test at the unit; if pressure and flow test fine everywhere else in the house but the tankless still won't fire, that points at the sensor rather than the supply.
Getting to it safely means opening the appliance's water and gas connections, so this is left to a licensed technician even though the part itself is simple.
It can help reduce sediment-related fouling over time, though Burnaby's municipal water is already relatively soft, so the bigger factor locally is usually the condition of the home's own plumbing feeding the unit.
No — once flow is detected correctly again, the unit fires and modulates normally with no lasting efficiency impact.
Most flow sensor repairs are completed within an hour or two once diagnosed.
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