Boiler pilot assembly dirty signs in Greater Vancouver

On boilers with a standing or spark-lit pilot, the pilot assembly must stay clean to light reliably and hold a steady flame. When it gets dirty, the boiler may struggle to ignite, drop out shortly after lighting, or refuse to fire at all. Greater Vancouver homeowners often see these symptoms after a boiler has sat idle.

Signs of a dirty pilot assembly

The pilot assembly includes the small pilot burner and a flame sensor or thermocouple that confirms the pilot is lit before the main burner is allowed to fire. Dust, lint, and corrosion can clog the tiny pilot orifice or coat the sensor, so the pilot burns weakly, the wrong colour, or goes out. A coated sensor may fail to prove the flame even when it is lit.

Typical signs include a pilot that will not stay lit, a yellow or wavering pilot flame instead of a steady blue one, repeated lockouts shortly after ignition, or the boiler simply failing to start.

• Pilot lights but will not stay lit
• Yellow or weak pilot flame instead of steady blue
• Boiler locks out soon after the pilot ignites
• Boiler fails to fire because the flame is not proven

What to do safely

Cleaning the pilot orifice, flame sensor, and thermocouple involves the gas-side of the boiler and is a job for a licensed technician. A homeowner can confirm the simple things: the thermostat is calling for heat, the boiler breaker is on, and any manual gas valve to the boiler is in the on position, but should not disassemble the pilot.

If the pilot will not stay lit after the basics check out, schedule professional service. If you ever smell gas, do not attempt to relight; leave the home and call your gas utility's emergency line first.

• Confirm the thermostat is calling and the breaker is on
• Check that the manual gas valve to the boiler is on
• Do not disassemble or clean the pilot assembly yourself
• Leave and call the gas utility if you smell gas

Frequently Asked Questions

What causes a pilot to keep going out?

A dirty pilot orifice, a coated or failing flame sensor or thermocouple, or a weak pilot flame can all cause the pilot to drop out. These are gas-side components a technician should clean or replace.

Can I clean the pilot assembly myself?

No. The pilot, sensor, and thermocouple are part of the gas system and should be cleaned or replaced by a licensed technician to keep the boiler safe and reliable.

Why does the boiler lock out right after the pilot lights?

If the flame sensor is dirty it may fail to prove the pilot flame, so the control locks out for safety even though the pilot appears lit. Cleaning or replacing the sensor usually resolves this.

Is a yellow pilot flame a problem?

Yes. A healthy pilot is steady and blue. A yellow or wavering flame can indicate a dirty pilot or poor combustion and should be checked by a professional.

HeatLand Heating & Cooling is a licensed and insured, TSBC-certified HVAC company serving homeowners across Greater Vancouver. Our technicians diagnose the real fault, explain your options in plain language, and complete the work safely and to code.

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