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water heater pilot light won’t stay lit

When the pilot light won’t stay lit, your gas water heater won’t be able to produce hot water, which makes troubleshooting and fixing the problem a top priority. 

This article will explain the top 10 reasons a water heater pilot light goes out or won’t light at all. We’ll help you troubleshoot and find solutions to fix the problem so your household will have hot water again.

There are 10 basic reasons your pilot light either won’t stay lit or won’t light at all:

#1- Spark Ignitor

If there’s a problem with the spark ignitor, you won’t be able to light your pilot light. Most newer gas water heaters have a sealed chamber that utilize a spark ignitor to light the pilot light, rather than manually lighting the pilot with a match.

The spark ignitor is typically located near the gas control valve. When you press the spark ignitor button, it’ll generate a spark to light the pilot.

Troubleshooting

There’s a couple things that could be causing this problem so you’ll need to do a little troubleshooting.

1. In order for the spark ignitor to work properly there needs to be a full circuit between the spark button assembly and the wire.

A spider web or dust build-up could prevent the spark from firing.  A quick shot of compressed air should clear any debris from the area.

2. Another issue could be the wire running from the spark ignitor button to the spark ignitor within the burner assembly.

If you’re sure that your spark ignitor button is properly working, then the problem could be that its grounding in the wrong place. This could cause the spark to be generated no where near where it should be, such as the frame.

3. The problem could be the spark ignitor itself. If the spark ignitor is worn or not working properly it won’t be able to generate a spark. 

Replace the spark ignitor and check that the spark is jumping to the spark rod.

4. It’s also possible there’s a corrosion buildup on either the pilot light termination or the spark rod. If this is the issue it will prevent the spark from crossing.

Use non-soaked steel wool and gently clean the pilot light termination and the spark rod.

 #2 – Gas Supply

If the valve that supplies gas to the water heater is closed or partially closed, your water heater won’t be able to keep the pilot light lit, or light it at all.

Troubleshooting

There are several issues that could cause this problem:

1. Follow the gas line that supplies your water heater with gas. By code, all gas fueled water heaters are required to have a valve that allows you to shut off the gas supply.

In most cases, it’s a ball valve and the handle may be a bright color, such as red, but don’t rely on the color.

If the ball valve is in the open position, the handle should be inline with the pipe. If it is not, you simply need to open the valve. However, make sure that the valve was not closed due a problem with your water heater.

2. It could also be the knob on the gas control valve. When you light your pilot there’s a gas control knob which needs to be pressed down which supplies the gas necessary for the pilot light to ignite.

If the knob is not positioned correctly you may not be able to press it down and it won’t be able to supply the gas necessary to light the pilot.

3. A less common cause, could be that the natural gas meter is shut off.

4. If you’re using propane, it could be that your propane tank is empty.

#3 – Low Gas Pressure at Pilot Head

If the pilot head isn’t receiving enough gas pressure, it won’t be able to sufficiently heat the thermocouple. 

The thermocouple’s job is to sense that the pilot light is burning, and it’s positioned so that the tip is next to the pilot flame.

When the pilot light is lit, the thermocouple senses the flame and generates a small electrical current which allows the gas valve to stay open.

When the pilot light goes out, the thermocouple cools down and stops generating voltage and the gas valve will close.

This important safety measure prevents unburned gas from being released into your home.

Troubleshooting

There are 2 possible issues that can cause this problem:

1. The pilot tube has a small orifice that can become clogged, or there is an obstruction somewhere within the tubing.

You can try to use compressed air, but because of the orifice’s size, they are often difficult to unclog.

2. It’s also possible that the pilot tube itself has become bent or kinked.

Depending upon the damage, you may be able to straighten it out. However, many times it’s best to purchase a new one.

#4 – Bent Pilot Tube Termination

As discussed above, if the thermocouple isn’t sensing enough heat it will shut off the gas valve. When the pilot tube termination is bent away from the thermocouple sensor the flame won’t be able to sufficiently warm the thermocouple to keep the gas valve open.

Troubleshooting

Although you can try to carefully bend the pilot light termination back into place, there’s a good chance it’ll break. 

To ensure that the problem is corrected it may be your best move to purchase and install the entire pilot assembly. However, you can also just replace the pilot tube termination.

#5 – Thermocouple Rod Position

If the thermocouple rod is not positioned correctly, the thermocouple will not sufficiently receive enough heat from the pilot to keep the gas valve opened.

Troubleshooting

Proper installation is critical in order to keep the thermocouple rod from moving out of position.

Sometimes all the parts are not used during the installation. When this happens, the thermocouple rod may not stay in position which could prevent it from sensing the flame.

If it was not installed correctly, you may want to purchase and install a new thermocouple. 

#6 – Dirty Thermocouple Rod

It could be that everything is set up correctly and the flame is in the proper position, however, the pilot light still won’t stay lit. 

This can happen if the thermocouple rod has developed a buildup of carbon dust.

Troubleshooting

It’s not uncommon for the thermocouple rod to develop an insulating layer of carbon dust which will prevent it from sensing the pilot flame.

When this happens, gently pull the thermocouple from the mounting bracket and rub it down with non-soaped steel wool to remove the buildup.

#7 Bad Thermocouple

If everything else checks out, it could be that the thermocouple itself is faulty. 

Troubleshooting

Many homeowners choose to just replace the thermocouple rather than performing additional troubleshooting. 

However, if you want to verify that the problem is indeed the thermocouple, you can test it using your multimeter to see if it’s providing the correct amount of millivolts. The video below shows you how.

#8 Loose Wire Connection or Bad Thermo Limit

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

Troubleshooting

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.

#9 – Windy Location

If your water heater was installed in a location where there’s a lot of strong air currents or the exhaust pipe is positioned in the wrong place, it could be that everything is in working order, but the pilot keeps blowing out or keeps jumping which prevents making the proper connection with the thermocouple.

Troubleshooting

If your pilot light flame is jumping around due to strong air currents, it’s a good idea to hire a professional plumber to help determine your best course of action.

#10 – Faulty Solenoid

Although, not common, the problem could be the solenoid within the gas valve.

If this valve is faulty it won’t stay open. This will prevent the water heater from receiving the gas required to keep the pilot light lit.

Troubleshooting

If you suspect this is your problem, you’ll want to ensure that everything else checks out. Although you can replace the solenoid itself, in most cases it’s best to replace the entire gas control valve.

Gas control valves can be expensive. If you choose to replace it, you can do it yourself, although many homeowners choose to hire a professional plumber to do it for them.

We highly recommend considering the age and health of your water heater before replacing the gas control valve.

Making the repair may be the right choice, however, there’s nothing worse than to spend hundreds of dollars only to have your water heater fail soon after.