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Why Your Water Heater Won’t Stay Lit (Plus the Best Solution in the World)

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Water Heater Wont Stay Lit: I am the type of person who quickly gets or feels cold. That is why I never take a bath without my heater on. For me, the water heater is the valuable part of a home, and I was so happy to have found the best water heater for my needs.

But just recently, my beloved water heater failed me. It won’t stay lit, so I have no idea whether it is working or not. When I brought it to a mechanic, I was surprised to discover that this was not an isolated case. Many people have experienced this dilemma too.

I would never want that to happen to me again. And I am sure you don’t want to experience the same thing too. That is why I did my research and discovered the reasons why a water heater won’t stay lit—and a few tips on how to fix it.

Why Your Water Heater Wont Stay Lit and How to Fix It

I was shocked to know that there are various reasons why a water heater won’t stay lit. By determining and understanding these reasons, you can be able to figure out what is wrong with your heater and have it fixed right away.

•    Curved Thermocouple

Majority of the water heaters in the market today come with a thermocouple. As years go by, wear and tear may cause the thermocouple to get bent too far away from the pilot light. As a result, it won’t be able to register heat, and the water heater won’t work as expected.

How to Fix it: 

The first thing that you need to do is to turn the gas off to prevent unwanted accidents. Next, try to locate the bent thermocouple and bring its back to its original shape or position. 

Ideally, it should be close to the flame of the pilot light. To know if the thermocouple is already in its proper position, check the pilot light. It must be blue in color. Additionally, the light should wrap around the heater’s sensor.

Water Heater Won’t Stay Lit

•    Blocked Thermocouple

If you do not usually open up your heater and clean its parts, there is a high chance that the dust, dirt and grime have accumulated inside it which may lead to the blockage or obstruction of the thermocouple.

Water Heater Wont Stay Lit

One of the roles of a thermocouple is to turn off the heater’s gas when it detects that the pilot light is turned off. If this component is obstructed, it may not be able to receive the electric current from the pilot light. This can cause gas outage which will lead to the failure of the water heater to work as intended.

How to Fix it:

Once again, make sure that you turn off the gas first before you open the water heater. Also, you need to check if the thermocouple is already cool enough to be touched. After that, clean the thermocouple using sandpaper.

•    Damaged Thermocouple

If you take a look at the thermocouple and it is not bent or does not feature any signs of dirt, it may mean that the thermocouple is already broken. 

How to Fix It:

Take the precautionary measures mentioned above—switch off the gas and wait for the thermocouple to cool down. 

After that, unscrew the thermocouple then check if it is still working by using a multimeter to determine the amount of voltage that the thermocouple is emitting. If the reading indicates 20 MV below, it means that thermocouple is no longer working and you need to have it replaced.

•    Dirty Pilot Tube

If you have inspected the thermocouple and it is clean, not bent and still working correctly, the next water heater component that you may need to inspect is the pilot tube. 

Water Heater Wont Stay Lit

Just like the thermocouple, dirt and grime can also build up in these tubes which may impede the flow of gas into the heater.

How to Fix It:

Fixing this issue is quite easy. All that you have to do is to turn off the gas then wait for a few minutes for the heater to cool down. Clean the tube by removing dust, dirt or any particles with the use of a small needle.

•    Bent Flex Tube   

If you have ruled out the pilot tube and thermocouple issues, then the next thing that you should check is the flex tubing. This is the tube that connects the gas controller to the heater to ensure that it will receive a steady stream of gas.

But just like the thermocouple, it may also get bent or kinked at certain parts. When it does, the amount of gas that the heater will receive may not be enough for full operation.

How to Fix it:

Turn off the gas source and wait for a few minutes before opening the water heater. Once it has cooled down, locate the flex tube and look for signs of bending or kinking. If you found any, just unkink it.

If the tube does not go back to its original shape even after you have unkinked it, it may have to be replaced.

•    Main Control Valve Problems

It is also possible that the pilot light of the heater won’t stay lit because of issues with the main control valve. However, this is quite rare, so you need to explore other possibilities first before considering this.

How to Fix it:

If the main control valve is the issue, it should be replaced. But it should be handled only by a certified gas technician. 

To prevent this kind of problem in the future, make sure to maintain your water heater properly. This video will tell you how


When your water heater won’t stay lit, it will fail to provide you with the hot water that you need. This issue can be due to various reasons. To determine what the possible cause is, try to check the different components of the heater—thermocouple, pilot tube and flex tube.

The control valve can be an issue too. However, it should be your last area of consideration. You should check the other components first.

Do you know other possible reasons why a water heater won’t stay lit? If so, then please share them with us below.





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1 thought on “Why Your Water Heater Won’t Stay Lit (Plus the Best Solution in the World)”

  1. Do not do this! If you live in the UK you have to be Gas Safe registered to work on gas appliances otherwise you are breaking the law & risk serious injury or death

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