How to light a water heater pilot light

First, check which kind you have

A. O. Smith describes three common setups, and the label on the front of your heater says which one you have:

• Push-button (piezo) igniter. Most standard tank heaters. You hold the gas knob in and click a button that makes a spark at the pilot.
• Match-lit pilot. Older heaters with no igniter button. You hold the knob in and light the pilot with a long lighter.
• Electronic ignition. Heaters that plug into a 120-volt outlet light the pilot or burner automatically. A. O. Smith's manual for these models says not to try to light the pilot by hand. Some electronic models have no pilot at all and use a hot surface igniter instead.

A. O. Smith says the label and your owner's manual come first, ahead of any general guide, including this one.

Before you start: safety

The safety block on A. O. Smith's lighting label says to smell all around the heater for gas before lighting, including next to the floor, because some gas is heavier than air and settles low. If you smell gas:

• Don't try to light any appliance.
• Don't touch electrical switches or use a phone in the building.
• Call your gas supplier from a neighbor's phone, or the fire department if you can't reach them.

The same label says to turn the gas knob by hand only, never with tools; if it won't move by hand, call a technician rather than force it. Don't use the heater at all if any part of it has been underwater; A. O. Smith says a heater whose gas control, burner or pilot was submerged needs to be replaced (see water heater after a flood). For more on gas odors, see water heater smells like gas.

How to tell the pilot is out

Lennox lists the usual signs: no hot water, or only some, the burner no longer clicking or humming on, and an error code or flashing light on newer heaters. To be sure, look through the small glass view port near the bottom of the tank. If you see a small blue flame, the pilot is lit; if not, it's out.

On A. O. Smith heaters with a status light, an unlit light means the control is off or the pilot is out. A light that stays on solid means the pilot went out recently; the valve won't let you relight until it cools, so wait 10 minutes. See water heater gas valve for the flash codes.

Steps for a push-button igniter

These are A. O. Smith's steps for its standard gas heaters with a piezo igniter and a Honeywell gas control:

1. Turn the gas control knob to Off.
2. Wait at least 10 minutes so any gas that built up can clear. If you smell gas after that, stop.
3. Turn the knob to Pilot and press it in fully. It should travel in about 1/4 inch.
4. While holding the knob in, click the igniter button about once a second. Keep clicking for up to 90 seconds, until the pilot lights or the status light begins to blink.
5. Once the pilot is lit, keep holding the knob in until the status light blinks.
6. Release the knob slowly and watch that the pilot stays lit, then turn it to your setting. Hot is about 120°F.
7. Put the outer door back on.

If the light doesn't blink after 90 seconds, release the knob and wait 10 minutes before trying again. A. O. Smith says the valve's circuitry requires that 10-minute wait between attempts, and to repeat the steps two or three times if needed. A steady single blink, about once a second, means the heater is working.

Older heaters: match-lit and Robertshaw valves

On a heater without an igniter button, A. O. Smith says to hold the knob in on Pilot and light the pilot with a long lighter, then release slowly and turn the knob to On. Lennox suggests a long-reach lighter or extra-long fireplace matches to keep your hand away from the burner, plus a flashlight.

On heaters with a Robertshaw gas valve, you press a separate Reset button instead of pushing the knob in. A. O. Smith's service handbook explains why you have to keep holding: the pilot flame has to heat the thermocouple until it makes enough voltage to hold the gas valve open by itself. Let go too early and the pilot goes out.

Electronic ignition models

A. O. Smith's lighting instructions for its plug-in models are different, because the heater lights itself:

1. Turn off the gas at the manual shut-off valve, unplug the heater and move the On/Off switch on the gas control to Off.
2. Wait 10 minutes. If you then smell gas, stop.
3. Move the switch to On, set the knob to Low, and plug the heater back in.
4. The igniter lights the pilot on its own. Don't try to light it by hand.
5. When it's lit, the status light blinks a heartbeat (bright, dim, bright). Then set the knob to the temperature you want.

If it fails to light after several tries, A. O. Smith says to turn the gas off, write down any flash code and call a technician or your gas supplier. A. O. Smith also notes that if the electronic ignition system itself fails, there's no fallback, so it's a job for a professional.

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

• No spark. Darken the room and look through the view port while clicking the igniter; you don't need to hold the knob in to check. A. O. Smith says that if you can't see a spark, check that the igniter wire connections are tight.
• Spark but no flame. The heater may not be getting gas, the gas supply may be off, or on a new installation there may still be air in the gas line.
• Lights, then goes out when you let go. A. O. Smith says that points to the thermocouple or thermopile, which powers the safety valve. See water heater thermocouple and pilot light keeps going out.
• Not enough air. A. O. Smith warns that a heater boxed into a small closet or surrounded by stored items can struggle to keep a pilot lit and can release carbon monoxide; get a technician to fix the airflow before relighting. See water heater carbon monoxide.

After a gas outage, let the utility relight

If your gas was shut off by the utility, its crews may handle relighting. Xcel Energy in Colorado says it relights gas appliances free of charge after an outage and asks customers not to do it themselves. Policies vary, so check with your utility (see water heater not working after an outage).

Some cities run their own gas systems. In Hamilton, Ohio the city's 24-hour Emergency Utility Service answers 513-785-7550, and in Fort Morgan, Colorado the city Gas Department answers (970) 542-3910 during business hours, with after-hours calls going through (970) 867-4350.

When to call a pro

Call if you smell gas, the knob won't turn by hand, any part of the heater has been underwater, the status light shows a fault code, or the pilot still won't stay lit after two or three tries. A. O. Smith says most homeowners can relight a pilot themselves but recommends a plumbing contractor if you're unsure, or if the heater is in a tight spot that's hard to reach. Our gas water heater repair page covers those calls.

Local pages mentioned

• Hamilton, OH
• Fort Morgan, CO