Water Heater Pilot Light Won’t Stay Lit After Replacing Thermocouple

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Why Wont The Water Heater Pilot Light Stay Lit After Replacing The Thermocouple

Water Heater Troubleshooting – Pilot Won’t Stay Lit | Repair and Replace
  • 5. Re-install the thermocouple
  • Many people choose to simply replace the thermocouple when experiencing problems with their water heater pilot light.

    However, what happens if the issue persists even after youve installed a brand new thermocouple? Here are some of the most common core issues behind a faulty water heater light.

    How To Determine If You Have Gas Hot Water Heater Thermocouple Issues

    A thermocouple is a function on your water heater that senses the heat on the pilot light and allows gas to flow to the burner. A bad thermocouple will shut off gas to both the pilot and the burner, which is when people notice that the water heater pilot light is out.

    Your water heater pilot light works in concert with other parts. When your thermocouple detects an unlit pilot, it automatically shuts off the gas to your water heater as a safety precaution.

    If you determine that your thermocouple is indeed broken that means there arent any signs of being bent or dirty then its most likely that your device is broken. To fix this issue, you will need to replace the device or have it professionally repaired. This is a good place to clear up some confusion.

    Water Heater Pilot Light Keeps Going Out

    Make sure to follow the directions on your water heater label. If your pilot doesnt re-light, wont stay lit or keeps going out after a short time, you most likely have an issue with the hot water heater thermocouple. This can happen with age. For more information about life expectancy, read this article entitled how long do water heaters last? Lets discuss how to tell if a thermocouple is bad, below.

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    Why Wont My Pilot Stay Lit On My Water Heater

    It is very frustrating when you are trying to light your water heater pilot light but as soon as you release the pilot light knob the pilot light goes out. Luckily, this problem has a solution and in most cases a simple, fast and very cheap one.

    A water heater pilot light that wont stay lit is almost always caused by a bad thermocouple. It fails to send a signal to the gas valve to open up, meaning gas does no flow to the pilot and burner. It could also be caused by a faulty gas control valve or tripped thermal switch.

    If your water heater pilot wont stay lit even after replacing the thermocouple, you most likely have a faulty gas control valve. It is a sign that the valve is failing to open and allow gas to flow to the pilot. You could also be dealing with a tripped or faulty thermal switch.

    A gas water heater depends on natural gas to heat the water but needs a little bit of electricity to function. It is very easy to know to know where the problem is, whether it is with the gas supply or its an electrical fault.

    If while lighting the water heater you can see a flame which goes out after releasing the knob, the issue is electrical and in most cases a bad thermocouple. On the other hand if you dont see a flame, you probably have a clogged pilot tube or the gas valve is off.

    Now let us look at detailed way of how to troubleshoot and fix a water heater whose pilot light that wont stay lit.

    Furnace Pilot Light Wont Stay Lit Replacing Thermocouple

    Pilot Light Won T Light

    It will be easier for you to solve the issue if you know why a pilot light wont stay lit after replacing the thermocouple.

    The most common reasons for pilot light failure after replacing the thermocouple are dirty furnace parts, faulty gas valve, defective thermocouple, improper draft positioning, and incorrect installation of the thermocouple. Below you will find effective solutions to these 5 problems.

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    Learning how to replace a thermocouple allows you to troubleshoot a gas furnace or water heater when the pilot light wont stay lit. Cleaning and replacing the thermocouple can help keep the appliance running smoothly and extend its life.

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    Why Your Pilot Light Wont Stay Lit

    Greg / Published: August 30, 2022

    Its the time of year when many people are getting their homes ready for winter. One important task is making sure your fireplace is in working order. A common problem with furnaces, heaters, and fireplaces is that the pilot light refuses to stay lit. There are a few things you can do to troubleshoot the problem, but if you have tried all of these things and your pilot light still wont stay lit, it may be time to call a professional.

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    Improper Air Flow Or A Strong Draft Blows The Pilot Out

    If your pilot light re-lights easily after going out overnight, its possible it was blown out by a draft. This can happen on excessively windy days or nights. A leak in the output duct of the furnace could cause air to blow into the area. Keep every intake air register in your home open and clear to avoid a vacuum effect in the inlet.

    Loose Wire Connection Or Bad Thermo Limit

    Top 10 Gas Water Heater Pilot Light Problems! Won’t Light, Won’t Stay Lit!

    Sometimes the problem is as simple as a loose wire connection. Or it could also be that the thermo limit was triggered.


    Check the wire connection at the gas control valve to ensure that it has a tight fitting. If everything looks good, it could be that the thermo limit switch needs to be reset.

    There are two thermo limit switches, one is resettable and the other is not.

    If the resettable limit gets too hot, it will trigger and shut down the gas supply.

    Although it can be reset, we highly recommend contacting a professional to troubleshoot the situation.

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    Reset/replace The Thermal Switch

    A water heater thermal switch is a safety device at the bottom of the water heater that trips and cuts off power to the gas control valve in case of excessive heat in the chamber. This usually happens when the vent or air inlet screen at the bottom of the heater are blocked.

    With a tripped thermal switch, you will have an open circuit, and the gas valve will just not open, allowing air to flow to the burner. You will therefore find that the pilot light will not stay lit when you release the valve/button.

    Apart from tripping, the thermal switch could be faulty as well. You should therefore start by trying to reset the switch and if that does not work test for continuity.

    This is how to repair a water heater thermal switch:

    • Remove the cover at the bottom of the water heater.
    • Look for a small button between the 2 switch terminals.
    • Press the button in. You should hear it click, but sometimes it will not.
    • Try to relight the pilot.
    • If the pilot light stays lit after releasing the button/valve, then your problem is fixed.
    • Test for continuity across the 2 terminals if the button wasnt tripped in the first place.
    • Disconnect the 2 wires from the 2 terminals.
    • Set your multimeter to the lowest ohms of resistance or to beep if it has that option.
    • Place the 2 multimeter probes on the 2 thermal switch terminals.

    If there is continuity then the thermal switch is good. A negative continuity test means the thermal switch is defective and will need to be replaced.

    Reason : Kink In The Flex Tube

    The flex tube provides fuel via the gas controller. On occasion, the tube can become kinked, interrupting the flow of gas.

    This is one of the most common reasons the burner wont stay lit, even when the pilot seems to be in working order. While not as common as thermocouple issues, its an easy fix and should thus be rules out early on.

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    How To Replace A Thermocouple In A Furnace

    If cleaning the thermocouple doesnt solve the problem, you may need to replace it. Thermocouples are relatively inexpensive and can be found at most hardware stores. To replace the thermocouple, remove the old one and screw in the new one. Be sure to tighten it securely, so it doesnt come loose and cause a gas leak. Once you have replaced the thermocouple, turn on the furnace and check to see if the pilot light stays lit.

    If your pilot light still wont stay lit after trying these troubleshooting tips, its time to call a professional. They will be able to diagnose the problem and make any necessary repairs.

    Weak Gas Regulator Can Make Pilot Light Keeps Going Out

    Pilot Light Will Not Stay Lit

    You have a gas regulator outside your house if you have gas appliances. A malfunctioning gas regulator may prevent your furnace from receiving enough gas to maintain its pilot light. If you notice pilot light problems on more than one appliance, such as your water heater, you may have a faulty or weak gas regulator.

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    Water Heater Pilot Light Issues:

    Lets start by explaining the water heater pilot light so you can better understand how it functions. A pilot light is a small flame present to ignite the gas burner on your water heater. A functioning pilot light should appear blue in color, which can help you determine whether or not your pilot light is working.

    How To Clean A Thermocouple

    A pilot light may not light due to a buildup of soot and carbon on the thermocouple. Cleaning the thermocouple can fix the issue and extend the life of the device.

    • Locate the pilot assembly and find the thermocouple. Usually, the tip of the thermocouple touches the pilot light.
    • Use an adjustable wrench as needed to remove thermocouple from the gas valve.
    • Detach the thermocouple from the pilot assembly. Some thermocouples can be pulled free, while others require screws to be detached with a screwdriver first.
    • Gently scrub the thermocouple with the abrasive side of a sponge or scouring pad to remove the soot. If you use steel wool, take extra care to avoid scratching the coating.
    • Reattach the thermocouple to the pilot assembly and the gas valve.
    • Turn the unit back on and test it to see if the pilot stays lit.

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    How To Replace A Damaged Thermocouple In A Water Heater

  • Use an adjustable wrench to loosen the nut connecting the thermocouple to the control valve and remove the gas line from the pilot line.
  • Pull out the thermocouple with the whole burner assembly.
  • Gently pull the thermocouple out from the burner assembly.
  • Push a new thermocouple into the slot. If theres a screw to hold it in place, tighten it.
  • Reattach it to the control valve and the gas line to the pilot light.
  • Note: Go for a universal thermocouple if you cant get the thermocouple specific to your water heater.

    Main Thermostatic Control Or Gas Valve


    The thermostatic control or gas valve can also be the possible reason for the pilot light tripping off repeatedly. It is also called the main control valve.

    This problem occurs occasionally, but it is a potential cause of a water heater pilot light wont stay lit. This problem also needs a professionals knowledge and expertise.

    They will thoroughly inspect the part with a multimeter to find out if it is faulty. If yes, they will either repair or replace the part.

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    Water Heater Pilot Light Wont Stay Lit

    If you have followed these steps and your water heater pilot light wont stay lit, you may need professional help to fix the problem, give All Masters a call if you live in Arlington TX, and we can fix any of your hot water heater thermocouple or pilot light issues!

    Ask about troubleshooting why your pilot light wont work right over the phone via our new video chat app in the Arlington and greater DFW area.

    Need help with the pilot light on your furnace? See our HVAC services page for more details.

    Reasons Why Your Water Heater Keeps Turning Off

    Like most tools and equipment at home, there are many reasons why your water heater keeps turning off. It is rather unfortunate that the reasons can be several, some known but others unknown to you. In either case, understanding the causes will help you to prevent future heating outages and save money, eventually.

    The potential reasons why you water heater keeps turning off or the water heater pilot light wont stay lit include:

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    Why Does My Water Heaters Pilot Light Keep Going Out

    Getting the cold shoulder from your shower? Youve discovered its because your water heaters pilot light has gone outagain. You keep lighting it, but it does not want to stay lit.

    So, whats the problem?

    There are two common sources.

    1) Problems with the thermocoupleUsually, a problem with the thermocouple causes the pilot’s light to go out.The thermocouple is the small copper rod that the pilot light hits. The thermocouples job is to shut a gas safety valve if the pilot light goes out.Thats important because gas is always being supplied to the pilot to keep the flame lit. But if the pilot flame goes out, then the gas would still be released. After a while, the gas could collect in your home and become a health hazard.However, if theres an issue with the thermocouple, the safety valve will shut even if the flame is still lit.Use the schedule service button to get back in hot water!Common thermocouple problems include:

    a) Dirt/soot on the thermocouple Any buildup on the thermocouple can block the flame, preventing it from being properly heated. To fix this, wait for the thermocouple to cool down and gently clean it with a wire brush or sandpaper.b) Thermocouple is bent The gas valve will shut if the thermocouple is bent away from the flame where the flame cant reach it. Wait for the thermocouple to cool down and bend it back.c) Damaged thermocouple If the above two arent the problem, the thermocouple may be malfunctioning and needs replacing.

    Unclog The Pilot Tube

    Modine Garage Heater Pilot Light Won T Stay Lit

    As weve mentioned, it is quite common for the pilot tube to get clogged with gunk, which could disrupt the gas flow, as well as the functioning of the pilot light.

    You can unclog the pilot tube in just a few simple steps. Under the access cover, there should be the pilot orifice, which you have to unscrew by twisting it to the left.

    Take a cotton swab and wet it with some rubbing alcohol. Then, use it to reach all the areas of the pilot tube, making sure to remove as much gunk as possible. You may also use a toothpick for tighter areas.

    Once youve cleaned the pilot tube and its elements, put everything back into its initial position. Try relighting the pilot by holding down the control knob while lighting the pilot with a long match or wand lighter.

    Once the pilot ignites, it is necessary to still hold the control knob down, which will release any excess air from the pilot tube, ensuring that the gas flow is smooth.

    Make sure to check if your pilot comes with an automatic igniter since these models do not require a match or lighter to ignite.

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    My Pilot Light Wont Light On Water Heater What Now

    Need advice on what to do when water heater pilot light wont light or when your pilot light keeps going out on your gas water heater? This doesnt always signal the need water heater repair or replacement in Arlington TX. When the pilot light goes out, you should know how to light a gas water heater pilot light.

    Your first step is obvious: to try to re-light the water heater pilot light. First things first, try to light it again before assuming there is a major problem. The below video will demonstrate how to light your water heater pilot light.

    Dirty Or Damaged Thermocouple Explains Why Pilot Light Keep Going Out

    A faulty, misaligned, dirty, or damaged thermocouple is often the culprit behind your pilot light going out. The thermocouple is an automatic safety shutoff device that prevents the gas valve from opening if the pilot light is out. If there is a problem with your thermocouple or if it is simply covered in dirt and debris, you may experience pilot light problems.

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    Can I Replace A Thermocouple Myself

    Yes. If you are DIY-inclined, you may be able to replace the thermocouple yourself. To do so its easiest to shut off the gas valve and remove the whole burner and thermocouple assembly. Though if you have no clue how to do small repairs, its better and safer to . A technician can also inspect your water heater for other issues and offer advice or tips towards any current/future problems.

    Reasons Furnace Pilot Light Wont Stay Lit After Replacing Thermocouple

    Boiler Pilot won’t light / Replacing the thermocouple if the pilot wonât stay lit

    A functional furnace often slips into the background when it comes to efficiency, safety, and overall performance.

    Unfortunately, its normal for problems to arise with the furnace pilot light. This includes the pilot light not staying lit after replacing the thermocouple.

    A furnace pilot light wont stay lit after replacing the thermocouple because the pilot burner is unclean or the gas valve has a bad magnet. Its recommended to clean the pilot burner using a wide bristled brush to remove debris. If the gas valve has gone, its best to call a specialist to replace the gas valve.

    Its essential to avoid a situation where the furnace pilot light doesnt work because the thermocouple was replaced.

    If this issue pops up, it is best to look at a solution that is straight to the point and will bring the furnace pilot light back to life as necessary.

    Here is a look at why a furnace pilot light wont stay lit and what to do about it moving forward.

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