Why won't my gas fireplace pilot light stay lit?

A gas fireplace pilot that will not stay lit almost always means the safety system cannot tell the pilot flame is burning, so it shuts the gas off. The cause is usually a worn thermocouple, a pilot flame that is too low or not touching its sensor, a weak millivolt generator or a faulty gas valve. Each of those is a repair on a live gas appliance, so it belongs to a licensed technician. Kingsman's label says that if the pilot will not stay lit after several tries, you should turn the gas control to "OFF" and call your service technician.^[1]

What is happening inside

Many gas inserts and fireplaces use a standing pilot with a flame safety device. The pilot flame heats a sensor, and the sensor holds the main gas valve open. If the sensor cools or stops signalling, the valve closes and the pilot goes out, which is exactly what it is built to do. For how the whole unit works, see how a gas fireplace insert works.

The usual causes

Kingsman's troubleshooting chart for a pilot that will not stay lit after the lighting instructions have been followed carefully lists a defective thermocouple, a defective valve magnet and a wall switch or wires that are defective.^[1] In plain terms:

• A weak or worn thermocouple. Kingsman's chart says to replace the thermocouple if the pilot will not hold.^[1] If the pilot still will not hold after the thermocouple is replaced, the chart points to the valve.^[1]
• A pilot flame in the wrong place. Kingsman says the pilot flame must impinge on the generator and the thermocouple.^[1] Its chart calls for the pilot to be cleaned or adjusted for maximum flame impingement on both, and for the thermocouple to be replaced if the pilot will not hold.^[1]
• A pilot flame that is too low or blowing. For a pilot that goes out often, the chart's cause is a pilot flame that is too low or blowing so that the pilot safety drops out.^[1]
• A weak millivolt generator. On millivolt units Kingsman says a millivolt generator should read 325 millivolts minimum.^[1] A technician needs a meter for that, not a guess.
• A vent problem. Kingsman lists a flame that lifts off the burner and goes out in less than 30 seconds as a sign that the inner liner has come off the flue or termination and the flame is starving for oxygen.^[1] That points to the venting, which is a different job from the pilot.
• Switch or wiring faults. A bad wall switch or loose wires show up in the same chart.^[1]

A yearly service is the best way to catch these early. See how often a gas fireplace should be serviced.

Why not keep trying yourself

Gas control and pilot parts sit on the gas line, and a mistake there can leak gas or let the unit run without its safety shutoff. Kingsman's manual is blunt about the gas control: if the control knob will not push in or turn by hand, it says not to try to repair it, because force or attempted repair may result in a fire or explosion.^[1] Its label also tells you to smell all around the appliance for gas, and if you smell gas, not to try to light the appliance.^[1]

Columbia Gas of Virginia says that if your pilot light goes out, it could be a sign that your appliance needs to be inspected and repaired by a qualified professional.^[2]

When to call a licensed pro

Call as soon as the pilot will not stay lit after several tries by the label's instructions, and straight away in these cases:

• You smell gas. Natural gas is naturally colorless and odorless, and the utility adds an odorant called mercaptan that smells like rotten eggs or sulfur.^[3] Columbia Gas of Virginia's advice for a gas smell or carbon monoxide symptoms is to go outside and call 911 and then call Columbia Gas at 1-800-544-5606.^[3] Do not try to light anything.
• Anyone feels unwell near the fireplace. Carbon monoxide poisoning can bring flu-like symptoms including headaches, dizziness, nausea, vomiting, irregular breathing or feeling ill.^[4]
• The glass is cracked, the flame lifts or goes out within seconds, or soot is forming. These point to the venting or burner, not the pilot alone.
• The unit has been wet, or has a repair history you do not know.

In Virginia, Virginia's Board for Contractors defines gas fitting contracting as the installation, repair, improvement or removal of gas piping and appliances annexed to real property.^[5] Hire a business whose licence covers that work, and ask for the licence number. The Board's guide says to verify license status online with the DPOR license lookup.^[6] Ask the technician to name the part that failed, to test the vent and the carbon monoxide levels after the repair, and to put the parts and labor in writing.

Getting help in Virginia

Loclis lists licensed local businesses by trade. Browse chimney, fireplace and stove services, read more chimney and fireplace answers, or see who can install and work on a gas fireplace insert in Virginia and what a gas insert costs.

To have it looked at, describe the problem once and licensed local businesses quote it.