How to Light a Water Heater Pilot Light

Before you start

Check three things:

You'll need a flashlight. If there's no igniter button, you'll also need a long-reach lighter.

Step by step: standing pilot with a push-button igniter

If the status light doesn't start flashing after 90 seconds, release the knob and wait 10 minutes before trying again. The manual says to repeat that at least two more times. After three failed tries, turn the knob to OFF and call a qualified person.

Older heaters with no igniter button

The steps are the same, except you light the pilot with a long lighter. A.O. Smith's FAQ says to use a long lighter while holding the knob in. Remove the outer and inner access covers, find the pilot burner (it's the small tube next to the thermocouple tip, not the big round main burner), and hold the flame to it while you keep the knob pressed.

Put both covers back before you leave. Running a heater with the burner door off messes up the airflow and can let flames roll out.

Sealed-combustion heaters

Most gas heaters built in the last couple of decades have a sealed combustion chamber with flame-arrestor protection, so you can't stick a lighter in there. The ProMax manual, for example, describes a Flammable Vapor Ignition Resistance (FVIR) system. On these, the igniter button is the only way to light it. If the igniter doesn't spark, see water heater igniter not working rather than forcing the issue.

Electronic ignition models

Some heaters have no standing pilot. They use a hot surface igniter that comes on only when the heater needs to fire. There's nothing to light by hand. If one of these won't fire, check that it has power and the gas is on, then call a pro. A.O. Smith's guide says there's no fallback if the electronic ignition fails.

If it won't light or won't stay lit

These are the usual reasons:

• It lights but goes out when you let go. A common cause is the thermocouple or thermopile, the sensor that powers the pilot safety valve. Test it before you replace it: how to test a water heater thermocouple.
• No spark. Check the igniter wire connection at the igniter. A.O. Smith says to make sure it's firmly inserted.
• Spark but no flame. Gas isn't getting to the pilot. Check the supply valve again. A kink or clog in the gas tubing is another cause.
• Goes out after a few hours or days. Drafts or not enough combustion air. A.O. Smith's troubleshooting guide adds that blocked air screens or filters restrict combustion air. Clean the filter at the base of the heater and see whether the area around it is cluttered.
• Electronic lockout. After several failed attempts, some controls lock out to prevent gas buildup. Wait and follow the manual.

Our full troubleshooting pages are pilot light won't light and pilot light won't stay lit.

Mistakes to avoid

• Skipping the wait after turning the knob to OFF. That wait is what keeps a pocket of gas from going off when you light it.
• Holding the knob for a second and letting go. The thermocouple hasn't warmed up yet, so the pilot drops out and people assume it's broken.
• Turning the knob straight to ON before the pilot is lit.
• Leaving the burner access covers off.
• Relighting over and over when it keeps going out. Once or twice is troubleshooting. Ten times is a gas appliance with a problem.

When to call a pro

Call a plumber or gas technician if the pilot won't light after three tries, keeps going out after you've relit it, burns yellow and lazy, or if you see scorch marks around the burner door. HomeGuide puts pilot light replacement at $50 to $200, and thermocouple replacement at $100 to $325. A bad gas control valve is the expensive one, at $150 to $550, and A.O. Smith says that part should be replaced by a professional. For more on that, see water heater gas control valve problems.