Older gas boilers and water heaters still running a standing pilot light depend on a pilot assembly, thermocouple and all, staying lit continuously, and once dust, lint, or a weak thermocouple signal gets in the way, a Maple Ridge appliance that's kept a household comfortable for years can suddenly stop holding a flame at all.
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Quick answer
A pilot assembly includes the small standing pilot burner, its thermocouple or thermopile safety sensor, and the tubing that carries a tiny, continuous gas flow to keep the pilot lit at all times on older-style gas appliances. Dust and lint can clog the pilot orifice over years, especially in appliances located in a basement or utility area, and the thermocouple itself weakens with age, both of which can cause the pilot to go out repeatedly or fail to stay lit when relit. A licensed technician diagnoses which part of the assembly is actually at fault before replacing anything.
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Unlike newer electronic ignition systems that light on demand, a standing pilot burns continuously, a small, steady flame that's always ready to ignite the main burner the moment there's a call for heat. A thermocouple or thermopile sits directly in that pilot flame, generating a small electrical signal only while the flame is present, and that signal is what keeps the main gas valve's safety circuit open. If the pilot goes out, the signal drops, and the safety circuit closes the gas valve automatically.
The pilot orifice is small, and dust or lint drawn into the appliance from its surroundings can gradually clog it, weakening the flame until it's no longer strong enough to hold the thermocouple's signal steady. Separately, the thermocouple itself degrades with age even without any clog present, producing a weaker signal that can drop out under normal draft conditions, which is why a pilot that relights fine but won't stay lit points more toward the thermocouple than the burner orifice.
A number of older homes in Maple Ridge's town centre and along established streets closer to the Fraser River still have original gas appliances running standing pilots that were never upgraded to electronic ignition, and basements in these homes tend to accumulate more dust and lint around mechanical equipment over decades than a newer sealed mechanical closet would. That's part of why pilot problems show up more often on these older systems than on newer construction.
| Symptom | Likely cause |
|---|---|
| Pilot won't light at all | Clogged orifice or gas supply issue to the pilot tubing |
| Pilot lights but goes out once you release the knob | Weak thermocouple signal not holding the safety circuit open |
| Pilot stays lit for a while then goes out on its own | Draft affecting the flame, or a marginal thermocouple signal |
| Pilot flame looks small, yellow, or unsteady | Possible orifice clog or air supply issue, worth inspecting |
Safety note
Never attempt to relight or repair a standing pilot assembly repeatedly on your own if it won't hold. If you smell gas, hear hissing at a fitting, or notice soot, leave the home first and call FortisBC's emergency line at 1-800-663-9911 from outside.
This usually points to a weak thermocouple signal not holding the safety circuit open once you release the gas knob, which is different from a pilot that won't light at all due to a clogged orifice.
Because this involves gas components, it's licensed gas fitter work in British Columbia; it's not something to attempt as a DIY repair even though the cleaning itself sounds simple.
Both are designed with safety interlocks, standing pilots rely on the thermocouple circuit while electronic ignition uses flame rectification, and a well-maintained standing pilot system remains safe when serviced properly.
That's a bigger decision tied to the appliance's overall age and condition rather than the pilot issue alone, and a technician can discuss whether repair or eventual replacement makes more sense for your specific system.
Older mechanical spaces, particularly in basements that have accumulated dust and debris over decades, expose the small pilot orifice to more of that material over time than a newer, more sealed mechanical closet would.
A technician measures its electrical output directly with a meter while the pilot is lit, confirming whether it's producing a strong enough signal rather than guessing from symptoms alone.
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