How to Light a Water Heater Pilot Light

Inspection of pilot light in water heater in residential home
Most people don't spend much time thinking about where their hot water comes from. As long as warm water pours out of the faucet when you twist the tap, that big tank lurking in the laundry room, garage, or utility area of your house tends to be ignored. But If you happen to have a gas-powered hot water heater, sooner or later you'll encounter an unpleasant reminder—only cold water will be coming out of your faucets, and it's likely to be because your hot water heater pilot light has gone out.

If you live with a large family or a couple of people who like to take really long showers, you're familiar with having your hot water run out from time to time. But when you have a flame outage, the water won't heat up at all, no matter how long you wait. This is an irritating problem, but fortunately, it is usually fairly easy to solve and you can likely take care of it by following a few simple steps on how to light a water heater pilot light.

Not sure you're up to the task, or suspect there's something more serious than a run-of-the-mill pilot outage going on? There's no need to worry—just call the team of licensed plumbers at Mr. Rooter Plumbing to handle it for you. Your local Mr. Rooter plumbers are highly experienced with water heater service, including troubleshooting, repair, maintenance, and replacement.

A Word of Warning

Before we explain the steps for how to light a water heater pilot light, it's important to cover some safety basics. When you're working with an appliance or system that is powered by natural gas, it pays to be extra careful. If you can smell a sulfurous odor, kind of like rotten eggs, in your home, or your carbon monoxide detector has gone off, that indicates that you have a gas leak. Carbon monoxide is a colorless, tasteless gas that is very toxic and can even be fatal when it is inhaled in large quantities. It is also highly combustible.

If you have reason to suspect a leak, you should turn off your gas supply at your main shutoff valve, open windows in your home, and get all people and pets outside until it can be checked out by a service professional. And, if you have any concerns that it may not be safe for you to attempt lighting your pilot light by yourself, there's nothing wrong with leaving that task for a licensed professional plumber to handle.

Steps to Get Your Water Heater Pilot Light Relit

Ready to get started? There are different types of water heaters on the market. The newer ones generally have electronic or hot surface ignition, but there are plenty of models still in use with standing pilot systems, and if that's what you have it will be helpful to know how to get that flame back on.

If you have a manufacturer's manual for your water heater unit, your first step is to check it for pilot lighting instructions. But if you don't have access to instructions anymore or they're difficult to read, you should be able to get it done by following these steps.

  1. Locate your gas shut-off valve on your unit (it is right beside where a gas supply pipe enters the heater) and turn your gas shut-off knob to the "Off" position to stop the flow of gas.
  2. Wait five minutes for the gas build-up to dissipate.
  3. Open your access panel cover to the burner chamber and shine a flashlight in so you can see your burner—it has two small gas supply tubes leading to it.
  4. Turn your gas regulator knob to "Pilot," press it in and hold it down to start gas flowing to the pilot burner. Some models have a button for pilot mode, which is usually red, that you need to press and hold instead to get the gas turned on.
  5. While you continue to hold the knob or button down, go ahead and light your pilot. Your unit may have a red or black igniting button that you can simply press, but if not, you'll need to use a long barbecue lighter and manually light your burner by touching the lighter flame to it.
  6. Continue to hold down that gas regulator knob or button for about one minute after your pilot flame is back on to give it time to heat up the flame sensor on your unit's thermocouple.
  7. Slowly release your gas regulator, keeping an eye on that flame to make sure it stays lit.
  8. Turn your gas valve to the "On" position and listen for a thump or a whooshing noise that indicates your main burner is ignited.
  9. Replace your access panel cover and pat yourself on the back for a job well done.

If you try these steps and you can't get a flame to come on or your experience differs in some other way from what is described above, there's likely a more serious problem with your unit. In that case, it's time to call in the pros and let a professional plumber take a thorough look at what's going on.

Should a Water Heater Gas Valve Be on "Pilot" or "On"?

The gas regulator knob on your water heater has three positions: "On," "Off" and "Pilot." When it's turned to "Off," there's no gas powering the pilot light or the heating elements in the tank. When it's on "Pilot," the pilot light is getting gas but the rest of the unit is not. When it's turned to "On," both the pilot light burner and the main unit should be getting gas. That means for normal function it should be set to "On" so the pilot is burning and the water is heating.

Why Does My Water Heater Pilot Light Keep Going Out?

It's pretty normal for a pilot light to go out every so often due to a normal fluctuation in gas pressure. But, once you get it relit, it should be fine again for a good period of time. If you light your water heater pilot light only to have it go out again a few minutes or hours later, that's a clear sign that something's not right—and that something is probably your thermocouple.

Your unit's thermocouple, which is also sometimes called a flame sensor, is a thermoelectric device that is designed to shut off the gas supply to your unit should the pilot light go out. When it is heated by flame, it produces a small electric current that keeps your pilot gas valve open. If the pilot goes out, the thermocouple cools down, and the current stops, shutting the gas valve that supplies the flame. Your thermocouple provides an important safety function because it's dangerous to have a valve open when the flame is not burning.

Since they rely on each other to work properly, the flame can't stay on if your unit has a dirty, bent, or otherwise faulty thermocouple. That's why a broken flame sensor is the number one cause of a pilot light that won't stay lit—there may be nothing wrong with the burner itself, but the thermocouple can't detect the pilot burning away so it shuts down the gas supply, which in turn causes the pilot light to go out.

Depending on what exactly the issue is with the thermocouple, your local plumber will need to clean it, reposition it or replace it altogether. On the upside, thermocouples are very inexpensive parts and a simple replacement service should get everything functioning well again so you can get many more years of service out of your system.

Other potential problems that can cause your pilot light to go out frequently include:

  • The pilot tube or orifice is dirty
  • The flex tube is kinked
  • The main control valve is malfunctioning

What Should a Water Heater Flame Look Like?

When you get your water heater pilot light flame back up and running, you should take a good look at it to make sure it looks as it should and everything is back to normal function. But what exactly is it supposed to look like? Your pilot flame should be mostly blue, and it might have a bit of yellow at the tip. There's not exactly a set height for the flame itself, it's more about how it is positioned in relation to the thermocouple. Basically, it should be covering about half an inch of the tip of the thermocouple. If it's not long enough to properly heat the flame sensor, or it's going too high, it will cause problems for the unit.

If the flame is mostly yellow rather than blue, that is an indication that it's not getting enough oxygen. If it's more of an orange or red color, on the other hand, there is dust or other debris burning along with the gas. When you have an orange or yellow dirty flame burning right after the burner comes on, that's not necessarily a cause for concern—the dust should quickly burn away and the flame will go back to a blue color. If it doesn't, you should have a water heater professional check it out and give the burner a good cleaning.

Can a Pilot Light Cause a Fire?

While it is not very common for the pilot light in a gas-fueled water heater to start a fire, it is possible. This typically occurs with gas-powered water heaters that are stored in a garage, especially one that is not well-ventilated. The types of activities that are often done in a garage, such as pouring gasoline, mixing paint, or using solvents, produce flammable fumes that ignite when they reach the pilot light inside the water heater, causing a flashback fire. However, homeowners who are aware of the potential for trouble can avoid it by keeping flammable liquids far away from any appliance with a pilot light, and ensuring the room is adequately ventilated.

Homeowners with a gas water heater also need to be aware of the potential for carbon monoxide poisoning. An aging system that hasn't received regular, professional maintenance services will deteriorate over time and connections in the gas supply line can become degraded, allowing toxic carbon monoxide to seep into your home. Carbon monoxide can be fatal when it is inhaled in large quantities, so annual preventative maintenance is well worth it to ensure your home and family are safe. Maintenance service gives your local plumber the opportunity to inspect your system, notice potential safety issues, and get them resolved before they can become a problem.

How Can I Make My Water Heater More Efficient?

It's normal for tank-style water heaters to lose energy efficiency as they age from wear and tear damage that causes the unit to need more and more fuel in order to provide the same amount of thermal energy. That increases your energy costs and can make a significant difference in your utility bill. The best way to keep your system running efficiently for as long as possible is routine maintenance services, but even a well-maintained unit that is nearing the end of its life is no match for the new, high-efficiency models on the market today. One way to help your unit run more efficiently is to add an insulating wrap to your tank. Just a simple foil "jacket" on the tank can help it hold in the heat a lot better, which means it will use less energy to keep the tank hot.

Need Help Lighting a Water Heater Pilot Light? Call Your Local Mr. Rooter Plumber!

If you are having trouble getting your water heater pilot light on, or you can't get it to stay lit for long, rely on a plumbing professional for water heater repair, maintenance, and replacement services. The experts at Mr. Rooter Plumbing know what to do to make sure your household has all the hot water you need when you need it.

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