If your gas water heater relies on a pilot light for ignition, it can be extremely frustrating when you can't get the pilot to light or if it won't stay lit. Many newer water heaters no longer use a standing pilot light and instead use an automatic intermittent pilot or some other type of ignition system. However, if your unit has a standing pilot where there is always a constant flame, the unit won't be able to work until you can get the pilot to stay lit. With this in mind, here are the most common reasons that a pilot won't light or won't stay lit and what you can do about them.
1. There Is Residual Gas Inside the Unit
Before attempting to ignite your water heater's pilot light, it is important that you turn the gas off and let the unit sit for at least five minutes. This allows any residual gas to disperse from the lines and inside the unit. You don't actually need to shut off the gas valve. All you have to do is turn the pilot control knob to the "Off" position.
If there is any residual gas inside the lines, it can prevent the pilot light from igniting. This is because many water heaters have a built-in safety mechanism that prevents the pilot from lighting when gas fumes are still present inside the unit.
2. Automatic Igniter Isn't Working
Most pilot lights have an igniter button. This is similar to the automatic igniter on propane grills. When you press the button, it emits a small spark that ignites the gas and lights the pilot flame. The igniter often wears out and will no longer produce a spark when you press the button. This problem is easy to diagnose as you should be able to see it spark every time the button is pressed. If you don't see a spark, then you'll need to use matches or a stick lighter to ignite the pilot instead.
3. Pilot Tube Is Clogged
In many cases, the reason that you can't get your pilot light to ignite is that the pilot tube is clogged. This is a small metal tube that supplies the gas needed to ignite the pilot and keep it lit. The pilot tube often becomes clogged with debris, and this will prevent gas from flowing to the pilot light. If there is no gas, the pilot obviously won't ignite.
If you suspect that the pilot tube is clogged, you can use a needle or thin piece of wire to try to clean it out and remove any debris. After cleaning the tube, you can then try to relight the pilot.
4. Flex Gas Tube Is Kinked
The flex tube connects your main gas line to the water heater, and it supplies gas to both the burner and the pilot light. If the flex tube is kinked or damaged, it can prevent gas from flowing as it should. While some gas will still likely flow into the unit, it generally won't be enough for it to work properly.
Luckily, this is something that is extremely easy to spot. If you see that the gas tube is kinked, you will want to call a professional plumber to repair or replace it. This is definitely not something you should attempt to fix on your own as you could further damage the tube and potentially cause it to leak.
5. Thermocouple Is Dirty or Obstructed
If the pilot light still won't ignite or stay lit, the issue could be related to the thermocouple. When looking at the pilot, you will see a small metal rod near where the flame should be. This is the thermocouple, which is an important safety feature that works to detect if the pilot is lit.
The thermocouple controls the gas flow into the unit. When it detects the pilot flame, it opens up the valve to allow gas to flow into the unit. If the pilot light goes out, the thermocouple will detect that there is no flame and automatically close the valve to shut off the gas flow.
Over time, the thermocouple can become covered in dirt and grime. When this happens, it can prevent it from properly detecting when the pilot light is lit. If you attempt to light the pilot and the thermocouple is too dirty to detect the flame, the gas will automatically shut off as soon as you release the pilot control knob. As a result, the pilot light will also immediately go out.
If the thermocouple is dirty, it can usually be cleaned by gently scrubbing it with fine-grit sandpaper. However, it is not recommended that you do this on your own. The thermocouple is extremely fragile and it can easily be bent or damaged. When this happens, you will most likely need to have it replaced. For this reason, it is always best to hire a professional if you suspect your water heater has any thermocouple issues.
6. Thermocouple Is Faulty or Damaged
When the pilot is lit, the thermocouple should basically touch the flame. Sometimes it can get bent to where it is no longer close enough to the pilot to detect the flame. If the thermocouple is bent away from where the pilot flame should be, you can try to very carefully bend it back in place to see if this fixes the problem.
If not, there is a good chance that the thermocouple is faulty. Thermocouples can wear out with age. When this happens, it will need to be replaced before the water heater will be able to work again. This is a fairly simple repair, but it is still something that is best left to the professionals.
A plumber will be able to test whether the thermocouple is working using a multimeter. When the thermocouple is working properly, it will carry a small electrical charge. If the multimeter doesn't detect a charge, then this indicates that the thermocouple needs to be replaced.
7. Control Valve Is Worn-Out
If the thermocouple isn't the problem, then most likely it means that the pilot control valve is worn-out. The control valve houses the pilot control knob and is what allows you to control the gas flow and turn the pilot light on. If the main control valve goes out, the only solution is to hire a professional to have it replaced. This job is definitely a bit more costly and time-consuming than the other fixes, but it is still preferred over having to replace the entire unit.
Professional Water Heater and Plumbing Services
If you're having issues getting your pilot light to stay lit or any other troubles with your water heater, the team at Apex Plumbing, Heating, and Air Pros is here to help. Our licensed plumbers work on all makes and models of tankless and traditional water heaters. If your water heater isn't working for any reason, we can quickly diagnose the problem and determine the best way to fix it.
If the issue cannot be fixed, we also specialize in water heater replacement and installation. Our team also specializes in a full range of other residential and commercial plumbing services for residents of Columbus and the surrounding areas. To schedule an appointment to have your water heater serviced or inspected, give us a call today.