Water Heater Pilot Light Goes Off After Burner Shuts Off

Gas water heaters are known for their long lifespan, but they are not always trouble-free. One of the most common problems is the pilot flame going out. This can happen for a number of reasons, but more often than not, the issue is easier to fix than you think.

A bent or dirty thermocouple is one of the main reasons why the water heater pilot light goes off after the burner shuts off. A faulty thermocouple could also be the cause, or the heater may not have enough combustible air. Sometimes, an unsealed combustion chamber could be the culprit.

Why Does My Water Heater Keep Turning Off?

The thermocouple is the most likely culprit when your water heater’s pilot light goes off. However, it isn’t the only reason. Let’s check out the possible causes.

Dirty Thermocouple 

The thermocouple is one of the most important parts of a gas water heater. It acts as a sort of brain that tells the flame when to switch on and off. It also closes the gas valve when it senses that the pilot light is off, preventing gas leaks into your home.

Because it acts as a safety device, the thermocouple should be maintained clean at all times. When it gets dirty, the dirt and grime can prevent the electric current from reaching the thermocouple. As a result, the component will close the gas valve, causing the pilot light to go off.

Dirty Pilot Tube

The thermocouple isn’t the only part of your gas water heater that can get dirty. Another one is the pilot tube. 

This tube supplies gas to the pilot light for combustion. When dirt clogs it, the gas won’t pass through, and the pilot light will go off.

To fix the issue, simply clean the tube with a needle. Clean several times to dislodge all dirt and grime stuck inside the tube. 

Dirty/Clogged Air Inlet

Modern gas water heaters have an air inlet screen at the bottom that ensures proper airflow in the combustion chamber. This screen can get clogged with dirt, dust, lint, pet hair, etc. If the grime blocks airflow, the combustion chamber will lack proper venting, and the pilot light will go off.

Bent or Faulty Thermocouple

A dirty thermocouple isn’t the only reason your pilot light might go off. Sometimes, this component might be bent or damaged and fail to sense the flame. If this happens, it will shut off the gas supply, causing the pilot light to go off.

Bad Gas Valve

A damaged gas valve could interrupt the gas supply just like the thermocouple can. Thus, if you’ve ruled out the thermocouple issues, you should check this valve next. Make sure it opens and closes correctly; clogs or grime jamming the mechanism are relatively easy to clean, but sometimes, you might have to replace the valve.

Unsealed Combustion Chamber

An unsealed combustion chamber shouldn’t create any issues; after all, if oxygen can get in and carbon monoxide can get out, the pilot light would have no reason to go off.

However, the unsealed chamber could allow nearby drafts to get inside and blow off the light. You can solve this issue by sealing the combustion chamber or moving the location of the water heater if that could be the culprit.

Wrong Location

Another location problem regards the lack of airflow. If your water heater is located in a utility closet or another enclosed space that could be starved for combustible air, the pilot light might go off constantly. Venting the utility closet will generally solve the issue.

Pilot Light Goes Out Every Few Days – It’s Probably Dirt

A dirty thermocouple is the most frequent cause of a pilot light that goes out every few days and only when the burner shuts off. Cleaning the thermocouple is easy, and you don’t need special skills to do it. Simply follow the steps below.

1. Gather the necessary supplies

While cleaning the thermocouple is a great project for beginners, you need the right tools to tackle the task. Here’s what you’ll need: 

• Wrench
• 4-in-1 screwdriver
• Emery cloth 

2. Shut off the main gas valve

Safety is paramount when servicing a gas water heater. To prevent accidents, you should shut off the main gas valve located near the heater on the main supply line. Turn the knob or lever counterclockwise to tighten it.

3. Remove the burner assembly

The thermocouple is a small rod located on the burner assembly, and you’ll have to remove the whole assembly to access and clean it.

Unfasten the nut connecting the assembly to the control center with a wrench, then pull it out of its casing. If you haven’t worked on a gas water heater before, you could snap a picture before disconnecting it so that you can remember where each piece goes when you’re reinstalling it.

Once the assembly is out, pull off or unscrew the thermocouple (whether you have to pull or unscrew depends on the model of water heater you have).

4. Clean the thermocouple 

Sand the ends of the thermocouple with the emery cloth until it’s clean and shiny. Then, wipe it with a lint-free cloth to remove all traces of dust. 

If you want, you can also clean the burner by scraping off the debris with a screwdriver or a similar tool.

5. Reinstall the burner assembly

Place the thermocouple on the burner assembly and reinstall the assembly in the chamber, reversing the steps above. Tighten the nut by turning it counterclockwise, then turn on the gas supply.

Ignite the pilot, then set the water temperature and turn on the hot water in your bathroom or kitchen. Let it run for a few minutes (causing the burner to run), then turn it off. Check the water heater to see if the pilot light is on or not. If it isn’t, you might need a new thermocouple. 

Is It Dangerous If The Pilot Light Goes Out On A Water Heater?

It generally isn’t dangerous if the pilot light goes out on your water heater. Most modern appliances feature valves that close the gas supply automatically if the pilot light goes off. However, the thing might be dangerous if you have an old gas water heater.

If you notice that the pilot light is off but can’t smell anything unusual, you have nothing to worry about. The smell of rotten eggs is a sign of a gas leak.

Related Questions

Cleaning or replacing a thermocouple isn’t hard, but you might have other questions before troubleshooting your water heater. Find out the answers below.

How do I know if my pilot light is out on my water heater?

You don’t have to keep an eye on your water heater to know that the pilot light is off. The pilot light is responsible for igniting the burner when you need hot water. Thus, if you turn on the hot water faucet but only get cold water coming out of it, it’s a clear sign the pilot light is out (and the burner doesn’t ignite). 

You can also look inside the water heater – most units have a sort of window that lets you monitor the light, or you could open the door. The pilot light is a small flame that should be on at all times, so you can notice if it’s off.

What does a pilot mean on a water heater?

A pilot light is a small flame that remains ignited even when the heater is on stand-by. Its role is to ignite the gas burner when you open the hot water faucet or when the water temperature in the tank drops below a certain threshold, based on the type of water heater you have.

Does a water heater pilot light always stay on?

The pilot light on a gas or propane water heater should stay lit at all times. If it goes off, something’s wrong with the thermocouple, the burner, or the gas valves, and you should troubleshoot your system.

Do all water heaters have a pilot light?

Only the gas water heaters have a pilot light (regardless of what kind of gas they use). Electric water heaters don’t have a pilot light since there is no burner to ignite.

Conclusion

A pilot light that goes off after the burner shuts off can be a cause for concern, but it’s usually very easy to fix. You need to clean the thermocouple, replace it, or troubleshoot the burner or valves. Sometimes, the culprit could be the wrong placement of the heater. Thus, if you’ve fixed the thermocouple, but the problem persists, you should contact a technician.