Lighting the Pilot Light on Your Gas Water Heater

To start a gas water heater, you light the pilot light—a small flame that ignites the main burner when your water heater senses the tank temperature has dropped. The process takes about five minutes and requires only a long lighter or long matches. Most water heaters have the pilot light assembly at the bottom front of the tank, behind a small access panel or door.

Before you begin, turn off the gas supply at the control knob on the water heater itself. Set it to the "Off" position and wait five minutes for any residual gas to clear. This step prevents gas buildup, which is a safety hazard. If you smell gas at any point during this process, stop when ready, leave the area, and call your gas company's emergency line.

Key Takeaways

  • Turn the control knob to "Off" and wait five minutes before attempting to light the pilot to clear any gas buildup in the chamber.
  • Locate the pilot light assembly at the bottom front of your water heater, usually behind a small access door or panel.
  • Hold the control knob in the "Pilot" position while you light the pilot opening with a long lighter, then hold it there for 30 to 60 seconds after the flame appears.
  • Once the pilot light stays lit on its own, turn the control knob to "On" to restore normal operation and heat water.
  • If the pilot light will not stay lit after three attempts, the thermocouple may need replacement—a job for a licensed technician.

Locating and Preparing the Pilot Light Assembly

Open the access door or panel at the bottom front of your water heater. You will see a small metal tube (the pilot burner) and a control knob labeled with settings like "Off," "Pilot," and "On." Some models also have a red button or a spark igniter button nearby. Take a moment to locate these parts so you know where to direct your lighter flame.

If your water heater sits in a tight space, you may need a flashlight to see the pilot opening clearly. The opening is usually a small hole at the end of the pilot burner tube, roughly the size of a pencil tip. Knowing exactly where to aim your lighter before you start makes the process faster and safer.

Setting the Control Knob and Lighting the Pilot

Turn the control knob to the "Pilot" position. This setting allows gas to flow to the pilot burner without igniting the main burner. Hold the knob in this position throughout the lighting process—you will need to press it down slightly while you light the pilot, depending on your model. Check your water heater's label or manual to see if your knob requires downward pressure; most do.

Bring a long lighter or long match to the pilot opening and ignite it. You should see a small blue flame appear at the pilot burner. If the flame does not appear after three seconds, release the knob, wait 30 seconds for gas to clear, and try again. Do not attempt to light the pilot more than three times in a row—if it will not light, stop and call a technician.

Holding the Pilot Light Until It Stays Lit

Once you see the pilot flame, keep holding the control knob in the "Pilot" position for 30 to 60 seconds. This allows the thermocouple (a heat-sensing device near the pilot) to warm up and signal the gas valve that the pilot is burning safely. If you release the knob too soon, the pilot light will go out.

After 30 to 60 seconds, slowly release the knob and watch the pilot flame. If it stays lit, you have succeeded. If it goes out when ready, wait five minutes and repeat the process. Most pilot lights stay lit on the second or third attempt. If the pilot light goes out every time you release the knob, the thermocouple is likely faulty and needs professional replacement.

Turning the Water Heater Back to Normal Operation

Once the pilot light is burning steadily on its own, turn the control knob from "Pilot" to "On." This restores the water heater to normal operation. The main burner will ignite when the tank temperature drops below your set temperature, and the pilot light will remain lit to ignite it. You should hear a soft whoosh as the main burner fires up within a few seconds.

Check that the flame inside the tank chamber is blue with a small yellow tip at the center. A flame that is mostly yellow or orange, or one that flickers excessively, may indicate a dirty burner or air intake problem. If the flame looks wrong, turn the knob back to "Off" and contact a technician.

What to Do If the Pilot Light Will Not Stay Lit

If the pilot light goes out every time you release the control knob, the thermocouple is almost certainly the problem. The thermocouple is a small metal rod that sits in the pilot flame and generates a tiny electrical signal telling the gas valve to stay open. When it fails, the valve closes as soon as you stop holding the knob.

Thermocouple replacement is not a task for a home cook—it requires a licensed technician and specialized tools. Call a local water heater repair service and describe the problem: the pilot lights when you hold the knob but goes out when you release it. This description will help them diagnose the issue quickly. Replacement typically takes 30 to 60 minutes and costs between $150 and $300, depending on your location and the technician's rate.

Safety Checks After Lighting the Pilot

After the water heater is running normally, smell around the base and access door for any gas odor. A faint smell of gas is normal for the first few minutes as the burner settles in, but a strong or persistent smell means gas is leaking. If you detect a strong smell, turn the control knob to "Off" when ready, leave the area, and call your gas company's emergency line from outside the building.

Check that the access door closes fully and that no debris blocks the air intake vents around the base of the water heater. Blocked vents prevent proper combustion and can create dangerous carbon monoxide. Clear away any boxes, rags, or dust buildup you find. Your water heater should have at least six inches of clear space on all sides for safe operation.

Frequently Asked Questions

Why does my pilot light keep going out after I turn the knob to "On"?

The thermocouple is likely worn out and no longer generating the signal needed to keep the gas valve open. This is the most common reason a pilot light will not stay lit. A technician can replace it, usually in under an hour.

Is it normal to smell gas when I first light the pilot?

A faint gas smell for the first few minutes is normal as the burner warms up and any dust burns off. A strong or lingering smell is not normal and means gas is leaking—turn off the water heater and call your gas company's emergency line.

What if I cannot see the pilot opening because of the way my water heater is positioned?

Use a flashlight or headlamp to see into the access area. If the space is too tight, a small mirror angled into the opening can help you see the pilot burner. Some people also use a long barbecue lighter instead of matches for better reach and visibility.

How long should I hold the control knob in the "Pilot" position?

Hold it for 30 to 60 seconds after the pilot flame appears. This gives the thermocouple time to heat up and signal the gas valve to stay open. Releasing too soon will cause the pilot to go out.

Can I light the pilot if I smell gas in the room?

No. If you smell gas anywhere near the water heater, do not attempt to light it. Leave the area when ready and call your gas company's emergency line from outside. Gas in the air is a fire and explosion hazard.