Ignition failure on a Giant natural gas water heater usually traces back to gas supply, a dirty igniter or pilot, or a safety control holding the burner closed.
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Quick answer
When a Giant natural gas water heater will not ignite, the most common causes are an interrupted gas supply, a dirty or worn igniter or thermocouple/pilot assembly, a tripped safety control such as a high-limit switch, or a flame-sensing fault on electronic-ignition models. Some of these have simple homeowner-level checks, such as confirming the gas valve is open and the pilot has not blown out, but diagnosis of the ignition and safety controls themselves should be left to a licensed gas fitter.
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Depending on the model and age, a Giant tank water heater will use either a standing pilot with a thermocouple or thermopile, or an electronic ignition system that sparks or glows to light the burner on demand, with a separate flame sensor confirming the burner actually lit. In either design, several safety interlocks must all be satisfied before the main burner is allowed to fire, including adequate gas pressure, correct venting/draft, and a functioning flame-proving sensor. If any one of these is not satisfied, the unit is designed to refuse ignition rather than risk an unsafe condition.
A Technical Safety BC licensed gas fitter will measure incoming gas pressure, inspect and clean or replace the igniter, thermocouple, thermopile, or flame sensor as needed, verify venting and draft, and test the gas valve and control board with proper instruments. This is combustion equipment tied to a pressurized fuel supply, so this work is restricted to licensed professionals under BC law, not something to troubleshoot beyond the basic checks above.
| Situation | Typical Path |
|---|---|
| Newer unit, isolated ignition failure | Component repair (igniter, thermocouple, sensor cleaning) is usually sufficient |
| Older unit, repeated ignition failures, or a failing gas valve/control board | Replacement is often more sensible than stacking repairs on an ageing unit |
| Ignition failure alongside a gas odour | Not a repair-timing decision — treat as a safety issue first |
Damp coastal air in many Metro Vancouver neighbourhoods can accelerate corrosion on pilot assemblies, thermocouples, and igniters over time, which is a common contributor to ignition problems on older Giant units, especially those installed in unheated garages, crawlspaces, or exterior-wall utility rooms exposed to more humidity and temperature swings. Units installed on an exterior wall can also be more exposed to draft-related nuisance shutdowns during winter cold snaps.
Safety note
If your Giant water heater will not ignite and you smell gas at any point, stop attempting to relight it, leave the home, and call FortisBC at 1-800-663-9911 from outside. Do not attempt repeated pilot relights beyond the instructions on the unit's own label, and never bypass a safety lockout. Ignition system and gas valve repairs must be performed by a Technical Safety BC licensed gas fitter; CANRO holds gas licence LGA0043870.
A pilot that lights but will not stay lit usually points to a weak thermocouple or thermopile, or a draft affecting the flame, rather than a total ignition failure; a technician can test which it is.
A couple of attempts following the label instructions is normal, but if it will not hold after that, stop and call a licensed technician rather than repeating the process indefinitely.
Yes, electronic-ignition water heaters need power to operate their igniter and controls, so a power interruption will prevent ignition until power is restored.
Not necessarily; many ignition failures are a single failed or dirty component, which is often repairable, though recurring failures on an older unit are a stronger signal toward replacement.
Yes, many models will not allow ignition if their draft-proving safety is not satisfied, which is a deliberate safety feature, not a malfunction.
If it is only an inconvenience with no gas smell, scheduling a licensed technician within a reasonable time is fine; if you smell gas at any point, treat it as urgent and follow the safety steps immediately.
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