Why Does My Pilot Light Keep Going Out

Why Does My Pilot Light Keep Going OutThe pilot going out is a common occurrence for those that have water heaters or older gas furnaces. These types of heat appliances utilize pilot lights to light the main burner.

That can turn into a nuisance for both maintaining heat or hot water. If it’s the water heater you have to re-light the pilot and then wait for the water heater to heat the water. The same for a furnace.

You have to light the pilot light and then wait for the furnace to heat the home to a comfortable temperature. There are a few main reasons why this occurs, and we will describe them here. We want to help you find the solution to your problem because we know it can cause discomfort.

It is frustrating to have to continually re-light the pilot light so you can get hot water or heat. Is it the gas valve and thermocouple or something else?   

Why Does My Pilot Light Keep Going Out

testing the thermocouple with a multimeter


The number one reason why the pilot light keeps going out is the thermocouple. Either the thermocouple is going bad or it is dirty and needs to be cleaned. Thermocouples work by producing a small amount of voltage when it is heated. This is the pilot flame that provides the heat. A gas valve that uses a thermocouple needs the voltage from the thermocouple to keep the valve open providing gas to the pilot flame.

If the pilot valve (inside the gas valve) is not open then the main valve will not open. This is a safety feature to ensure the main burners have an ignition source. Without this safety feature, it would be possible to release a large volume of combustible gas. That can be dangerous. Thus the safety pilot.

If the thermocouple is going bad then it is not sending the correct amount of voltage to the coil in the gas valve. This will cause the coil to close the pilot valve preventing gas from getting to the pilot nozzle. In this case, the thermocouple needs to be replaced. Before purchasing a new thermocouple a check of the gas line to the pilot assembly should be done. In a few cases, debris got trapped in the gas line and blocked the gas.

Cleaning the tubing by blowing through it should clean all the debris from the line. The pilot assembly, pilot nozzle, and even the thermocouple should be clean. Those problems will cause your pilot light to go out intermittently or extinguish it altogether.

Gas Valve and Thermocouple

Pilot Burner

Pilot Burner

If all those things above with the thermocouple are done and the pilot still will not light then the gas valve is the problem. Since gas valves are not serviceable the gas valve needs to be replaced. An important test to do before condemning the gas valve is to test the thermocouple for proper output.

We have another page here at High Performance HVAC to help you test the thermocouple if you want to do it yourself. You will need a multimeter to accomplish the testing of the thermocouple. It would also help to have another person helping you or have alligator clamps for the thermocouple testing.

If the thermocouple gives you the proper numbers for voltage and all of the above has been done, then you can replace the gas valve. Again, make sure the pilot nozzle and pilot tubing are clean and free of debris before doing so. The most likely cause of your problem, in this case, is the coil in the gas valve is bad.

What causes the coil to go bad in the gas valve? It could be moisture, or it could be a power surge of some kind. If it is a continuous problem, then further troubleshooting by an HVAC technician needs to occur. If you are not comfortable replacing a gas valve, then please call a plumbing or HVAC service.

Drafts and High Winds | Why Does My Pilot Light Keep Going Out

The next possible problem that can keep your pilot light going out is an environmental problem. If the water heater or furnace is in a garage, then it may be necessary to make observations as to when the pilot light is going out. For example, is someone opening the garage door when this occurs? Is the wind blowing hard outside?

I have found this happening on some service calls during high wind periods. The high wind caused a draft that extinguished the pilot flame. Sometimes it occurred when a door was opened and other times not. In the “not” cases, the wind was coming down the flue or chimney.

In those cases, it became necessary for the person to get a chimney cap or flue cap. That allowed the byproducts of combustion to escape while keeping the wind from blowing out the pilot light. It is crucial, for troubleshooting purposes, to make a note of conditions outside and when the problem occurs. For Example:

  • When the wind is high like in the fall time
  • During a bad storm with high winds
  • Someone slamming a door too hard can create a draft that will extinguish the pilot light.
  • As noted above, when the garage door is open

Conclusion | Why Does My Pilot Light Keep Going Out

There is another option for you if you are frustrated with pilot lights. You can do a conversion from standing pilot to electronic ignition.

If you feel uncomfortable doing any of the things noted here call an HVAC service company or a plumber. Most plumbers deal with thermocouples and gas valves and can quickly and efficiently take care of the problem for you. The goal is to keep the pilot light lit and burning to provide ignition for the main burners. If you want to research other possibilities about converting to electronic ignition see our resources below. Thanks and happy heating!!

High Performance HVAC Heating & cooling

Why Does My Pilot Light Keep Going Out


Changing a Standing Pilot Boiler to Electronic Ignition

Thermocouples available here

Top Ten Reasons the Pilot Light Won’t Stay Lit Video