Boiler Pilot Light Won’t Stay On in Greater Vancouver

An older boiler with a standing pilot light that keeps going out leaves Greater Vancouver homes without heat — and the cause is almost always the thermocouple, the pilot assembly, or a draft reaching the pilot flame.

What This Symptom Means

The thermocouple is a safety device that generates a small electrical current when heated by the pilot flame. This current holds the gas valve open. If the thermocouple is worn, the flame is too small to heat it adequately, or a draft extinguishes the flame, the gas valve closes and the pilot goes out.

Common Causes

• Thermocouple worn or failing — no longer generating sufficient current
• Pilot orifice partially clogged — flame too small to heat thermocouple tip adequately
• Draft near the boiler reaching the pilot assembly
• Thermocouple not correctly positioned in the pilot flame path
• Low gas supply pressure affecting pilot flame stability
• Thermocouple wire damaged or connection corroded

What Homeowners Can Check Safely

• Relight the pilot following the procedure on the boiler label — this is a homeowner-safe task
• After relighting, note whether it stays lit for seconds (thermocouple) or minutes (draft issue) before going out

When to Call a Licensed Technician

Boiler systems involve pressurized hot water, gas, and electrical components. Do not attempt to open sealed components, adjust gas pressure, or bypass safety controls without professional diagnosis.

• Thermocouple testing with a multimeter — should generate 25 to 35 millivolts when hot
• Thermocouple replacement — inexpensive and common
• Pilot orifice cleaning
• Gas pressure verification
• Draft inspection at pilot assembly location

Frequently Asked Questions

How long does a thermocouple last in a boiler?

Thermocouples typically last 8 to 12 years. In older boilers that have not been serviced, this is one of the first components to fail. Replacement is straightforward and inexpensive, and often resolves persistent pilot outage immediately.

Is it worth repairing a pilot light on an old boiler?

Pilot light repairs (thermocouple, orifice cleaning) are relatively low-cost. If the boiler is otherwise functional and under 20 years old, repair makes sense. If the boiler is over 20 years old and has other aging components, use the service call as an opportunity to assess overall system condition and whether replacement is approaching.

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