Although no longer as common as they once were, pilot lights are still found on many gas-burning appliances like water heaters and fireplaces. If you have a gas furnace that is more than 15 years old, it may also use a pilot light instead of the electronic igniters found on newer furnaces. The purpose of a pilot light is to ignite the unit’s gas burners whenever it turns on, and it does this using a constant, steady flame. Whenever the unit needs to turn on, the gas valve opens and the flame from the pilot instantly lights the burners.

A pilot light can sometimes get blown out by a strong draft or gust of wind, and you will then need to manually relight it. There are also a few different issues that can cause your pilot light to keep going out or never stay lit when you try to relight it, and today we’re going to look at a few potential causes for this issue and what can be done to fix them.

1. Dirty or Broken Thermocouple

The thermocouple is one of the most important parts of a pilot light, and it is an essential safety measure that ensures that no gas will flow to the unit if the pilot light isn’t light. It is essentially a thin metal probe that constantly has a small electrical current flowing through it. This current enables the thermocouple to sense the heat from the pilot flame so that it can ensure the pilot light is on.

The thermocouple is what controls the unit’s main gas valve. If the pilot is out or the thermocouple doesn’t detect the heat from the pilot flame, the gas valve won’t open and the unit won’t ever turn on.

Although the thermocouple is fairly sensitive, it needs to directly touch the pilot flame to work properly. The fact that the probe is so thin means it can easily get bent so that it no longer touches the flame. If you try to relight a pilot light and the thermocouple is bent in a way that causes it to not make contact with the pilot light, the flame will instantly go out when you release the pilot control knob since the probe won’t detect the heat from the flame. This is something you can easily check for by looking to make sure that the probe is directly within the flame when you try to light your pilot.

The thermocouple can also wear out with age, which means no current will flow through it and the probe won’t ever detect that the pilot is lit. The only way to know if it is worn out is to test it for current using a multimeter, which is typically something you will need a professional to do. If they determine that there is no current flowing through the probe, then you will need to have the thermocouple replaced.

All that being said, the most common reason a thermocouple will stop working properly is that is coated in dust and grime. When this happens, all of the dust will basically insulate the probe and make it so that it can’t detect the heat from the pilot flame. The solution to this problem is usually to clean the probe using fine-grit sandpaper, and we would always recommend hiring a professional for this so that you don’t risk breaking the thermocouple.

Replacing a thermocouple is a fairly quick, easy and inexpensive relative to most repair costs. Nonetheless, we still wouldn’t ever recommend messing with the thermocouple on your own since if it breaks your unit, won’t work again until you can get someone to come and replace it.

2. Clogged Pilot Gas Tube

The pilot tube is what supplies the small amount of gas necessary for the pilot flame to stay lit. The tube is quite thin and can easily become blocked with dust and debris. A clogged pilot tube will usually prevent the pilot from lighting since no gas can flow. If you suspect this is the case, then it would be worthwhile to consider having a professional inspect your pilot to find out why it won’t light.

3. Faulty Pilot Control

The pilot control is what controls the gas flow and everything else, and it is also what you use when the pilot needs to be relit. Pressing in the control knob opens a valve so that gas can flow through the pilot tube. Once the pilot is lit, you will need to keep the knob pressed in for around 30 seconds to ensure that the thermocouple has enough time to heat up.

The pilot control can also fail due to age, and this will cause the pilot to go out and prevent you from ever relighting it. Luckily, the pilot control can also be replaced quite easily. While it is a bit more expensive than replacing a thermocouple, it is still far better than having to replace your entire unit. A faulty pilot control is also something that you will need a professional to check for as there is no way to know if it is working without the proper tools to test it.

4. Interruption to Your Gas Supply

A pilot light obviously needs a constant flow of gas to stay lit, and you will normally be able to smell the gas whenever you try to relight the pilot. If you don’t smell gas and your pilot won’t light, it could be that there is an issue with the gas supply to that particular appliance or to your entire home. Either a kink in a flex gas line or a gas valve that isn’t fully open can prevent enough gas from flowing for the pilot to light.

If there is no gas flowing to any of your other appliances, it means that the issue is with your main gas supply. It could be simply that someone has closed your home’s main gas valve or that your gas company has shut off your gas supply for some reason. Another possibility is that the gas regulator valve outside of your home has failed or is stuck closed, which is something that the gas company will need to check and replace if necessary.

If you have a furnace or boiler with a pilot light that keeps going out or won’t relight, Healthy Home Heating & Cooling LLC can test it to determine what the problem is and how to fix it. We specialize in all types of heating repairs as well as maintenance and new equipment installations, and we also offer a full range of cooling and indoor air quality services for customers in De Pere and the surrounding areas. If you have any questions about your pilot light or need to have it inspected, give us a call today.

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