Boiler Pilot Light Keeps Going Out? What to Check

Standing pilot or spark-lit?

Peerless’s two kinds. A standing pilot should always be lit. An intermittent pilot lights only when there is a call for heat, and goes out when the call ends, so seeing no pilot between calls is normal.

A spark-lit Peerless is not lit by hand. Peerless’s Series 63 and 64 label says its ignition device lights the pilot automatically, and not to try to light the pilot by hand.

Telling them apart. Burnham’s Independence offers a standing pilot on its IN10 to IN12 sizes, with a thermocouple, and intermittent ignition with an igniter and sensor. PG&E says many older gas appliances have a continuously burning pilot, while some newer ones have electronic igniters.

Relight it by the label

A standing pilot. PG&E says follow the maker’s instructions inside the burner compartment, and call a qualified professional if you cannot relight it yourself. The propane council says that if you choose to light it, follow the maker’s instructions, and do not try if you suspect a gas leak.

Peerless’s steps for its spark-lit Series 63 and 64. Set the thermostat to its lowest setting and turn off all power to the boiler. If the gas valve is not visible, remove the control access panel. Turn the gas control knob to OFF, wait five minutes, and smell for gas, including near the floor. If you smell gas, stop and follow the gas rules above. If not, turn the knob to ON, put the access panel back, turn the power on, and set the thermostat to the setting you want.

If it will not run. Peerless says turn the gas off by its label: set the thermostat to its lowest setting, turn off the power if service is to be done, and turn the gas control knob clockwise to OFF. Then call your service technician or gas supplier.

It lights, then goes out again

Why pilots go out. The propane council lists running out of gas or turning it off, too much or not enough ventilation, and a problem with the appliance or the gas system.

What you can look for. On a standing pilot that blows out now and then, Peerless’s contractor FAQ looks first for a draft from a window or doorway, or a clothes dryer in a small closed space pulling enough air to snuff it. If other gas appliances’ pilots also blow out, that could point to the gas flow or piping.

Then the parts. With nothing found around the boiler, Peerless says the cause may be the thermocouple, which senses the pilot flame, or the gas valve, and a technician tests both with its Standing Pilot Test Procedure. Burnham says the thermocouple makes the gas valve shut off the main burner and pilot gas when the pilot flame goes out.

Do not keep relighting it. The propane council says that if a pilot is difficult to light or repeatedly goes out, never try to fix or troubleshoot it yourself. Never try to let air out of the gas line, which releases gas.

Look at the pilot flame

A standing pilot. Peerless’s monthly check says the pilot flame should be medium blue, covering about 3/8 to 1/2 inch of the thermocouple. If it is yellow and lazy, turn off the gas to the boiler and call a qualified service agency.

A spark-lit pilot. Weil-McLain’s user manual for its CGa, CGi, EG, PEG and LGB boilers wants a blue flame, its inner cone around the pilot flame sensor, and the sensor glowing cherry red. A flame lifting past the sensor, a small one, or a yellow tip is wrong.

The ignition control and its light

It tries again by itself. Burnham’s Independence manual says that on its intermittent ignition, if the pilot flame goes out, the ignition module shuts off the gas and restarts the lighting sequence five to six minutes later.

The Independence’s green light codes. Two flashes mean a 5 minute retry delay because no pilot flame was detected. Three mean the flame failed while running. If it will not light on the next try, Burnham’s list for the technician is the gas supply, pilot burner, spark and sensor wiring, flame rod and burner ground.

The pilot is lit, the burners never fire

Something has to call. Burnham’s sequence starts with the thermostat calling for heat, and on a boiler with a vent damper, the main burners only run with the damper open.

A limit or the water. Peerless says its limit stops the boiler above the set steam pressure, or above the set water temperature on a hot water boiler, and restarts it by itself. Its limit control may include a low water cutoff that stops the boiler when it loses water: a steam boiler low water cutoff. If that cutoff has stopped it, Peerless says turn off the gas to the boiler by the label and contact a qualified service agency.

A tripped safety switch. Burnham says a tripped blocked vent switch or flame rollout switch stops the burners, and the boiler is not restarted until the cause is corrected. The rest is in a boiler not working.