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How to Replace a Water Heater Thermocouple in 9 Steps

Fact checked by Stephen Conklin

how to replace a water heater thermocouple

Does your gas water heater’s pilot light die out right after releasing the gas control knob? Does the burner not light up, or do you not have hot water coming out of your faucets and showers? These are all indicators of a worn-out water heater thermocouple.

The good news is that you can address these concerns by learning how to replace a water heater thermocouple. The process is straightforward, and I will describe the different steps you can take to change a thermocouple.

Table of Contents

Things You Need for This Tutorial


The thermocouple is an essential safety feature of many gas-powered water heaters. It works like a temperature sensor that shuts off the gas supply to the burner if there is no heat in the pilot light.

Changing the thermocouple on the water heater only requires a few tools and materials.


You need the correct thermocouple replacement for this activity. Unfortunately, you can only ensure you have the right replacement part by removing the old thermocouple and bringing it to the store.

Alternatively, you can check the owner’s manual for information about the thermocouple type, model, or series number found in your water heater. You can also try contacting the water heater manufacturer for additional information.

You might also need a manifold cover gasket replacement if the existing lining is in bad shape.

A soapy solution is also crucial for checking leaks in the connections.


You will also need screwdrivers and an adjustable wrench for removing the various fasteners securing the water heater burner assembly. In some cases, a utility knife can also be helpful.

Steps for Replacing the Water Heater Thermocouple


Step 1. Disconnect the water heater’s gas supply.

It would be best to disconnect the water heater from its gas supply to prevent any untoward incident. It does not matter if you have a water heater with a standing pilot or electronic ignition.

Check the water heater’s gas control valve and turn it off. You might also want to follow the gas supply line until you see a shutoff valve. Turn the knob to the OFF position, too.

Step 2. Remove the water heater’s burner assembly cover.

Some water heaters have electronic ignition instead of a standing pilot light. The ignition mechanism is part of the burner assembly and is protected by a manifold cover.

It is essential to remove the manifold cover to access the combustion chamber that accommodates the electronic ignition, thermocouple, pilot, burner, and burner supply tube.

Use the correct hand tool to loosen and remove the screws or nuts, fastening the manifold cover.

Step 3. Remove the water heater burner assembly.

It is crucial to remove the burner assembly to access and replace a hot water heater thermocouple. You can do this by pushing down on the burner supply pipe to loosen and free the thermocouple, pilot tube, and manifold connections.

Carefully slide the burner assembly out of the combustion chamber, ensuring you do not damage any of the internal components.

It would also be wise to check the burner assembly to see if it has a screw. Remove the fastener first before removing the burner assembly.

Step 4. Remove the gasket from the manifold cover plate.

The manifold cover has a rubber gasket that forms an airtight seal for the combustion chamber. Check its integrity to determine if it also requires replacement. It would be best to remove the gasket carefully if it is still in excellent condition. You will need this during reinstallation.

Now is the perfect opportunity to clean the manifold cover and the combustion chamber.

Step 5. Remove the old water heater thermocouple.

Apply firm pressure when twisting and pulling the thermocouple from its mount. It would be best to do this slowly to avoid deforming, bending, or damaging the thermocouple-pilot tube connection.

Pull the old water heater thermocouple through the manifold cover opening or a rubber grommet. You can also cut the thermocouple if you find it challenging to pass it through the grommet or manifold cover opening.

Pro Tip: I advise you to bring the old water heater thermocouple to the store to buy the correct water heater thermocouple replacement. It will also be an excellent idea to consider buying a new manifold cover gasket if you intend to change the old one.

Step 6. Install the new water heater thermocouple.

Grab the new water heater thermocouple and insert it through the manifold cover opening or the grommet. Next, position the thermocouple in the mounting bracket, carefully pushing it into place until you hear a click.

It is essential to place the thermocouple in the correct position. Ideally, the pilot flame should engulf the thermocouple’s upper half to 3/8 inch. If you do not position the thermocouple properly, your efforts to replace a thermocouple will be in vain.

Step 7. Reassemble the water heater burner unit.

Place a new gasket around the manifold cover if the old one is no longer practical. Otherwise, you can reinstall the old lining to create a perfect seal around the combustion chamber.

Reposition the burner assembly back into the chamber, fastening the screws if needed.

Place the manifold cover assembly on the panel and tighten the fasteners.

Step 8. Reestablish the water heater’s gas control valve connections.

Look at the water heater’s gas control valve and reconnect the thermocouple, pilot supply tube, and burner supply tube. Ensure the thermocouple’s mounting nut does not exceed a quarter turn after tightening it by hand.

Step 9. Reestablish gas supply and test the unit.

Turn on the gas shutoff valve and the gas control valve. Light up the pilot light according to the manufacturer’s instructions. Set the pilot control valve to the ON position and dial the desired temperature for the thermostat.

Make a soapy solution and drizzle a small amount over the connections. Check to see if there are bubbles present. If you notice bubbles, you might want to retighten the fasteners before retesting the water heater connections.

FIX IT Home Improvement Channel has an exciting video about replacing the water heater thermocouple. I recommend watching the video to help guide you through the process.


You now know how to replace a water heater thermocouple. The process is not as complicated as some people think, although it requires careful maneuvering of the thermocouple from the burner assembly.

If you think this tutorial helped you feel more confident about managing this gas water heater issue, your social contacts will also find it advantageous. I also like to request that you share this guide with them. Moreover, I will appreciate any comments you have about this tutorial.

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