The basic steps to relight a pilot light
To light a hot water heater pilot light, you need to locate the control knob (usually on the front of the tank), turn it to the "Pilot" position, press and hold the ignition button while holding a lit match or lighter to the pilot opening, and keep the knob pressed for 30 to 60 seconds after the flame catches. The pilot opening is a small brass tube near the bottom of the burner assembly, usually marked with a label or arrow.
Most modern water heaters have a piezo igniter button instead of requiring an external flame. If your heater has one, you straightforward turn the knob to "Pilot", press the ignition button repeatedly while holding a match near the opening, or press the button alone if the igniter is electronic. Once the pilot flame appears, hold the knob in the "Pilot" position for 30 to 60 seconds — this allows the thermocouple (a safety device) to heat up and sense the flame is present.
After the thermocouple warms, turn the control knob to "On" or the desired temperature setting. The main burner should ignite within a few seconds. If it does not, turn the knob back to "Off", wait five minutes, and try again.
Key Takeaways
- Turn the control knob to "Pilot", then press and hold the ignition button while lighting the pilot opening with a match or lighter.
- Keep the knob pressed for 30 to 60 seconds after the flame appears so the thermocouple can sense the heat.
- Once the pilot is lit, turn the knob to "On" and the main burner should ignite within seconds.
- If the pilot will not stay lit, the thermocouple may be dirty or failing, and you may need to clean or replace it.
- If you smell gas but see no flame after several attempts, turn off the gas and call a technician — do not keep trying to light it.
What to do if the pilot light won't stay lit
If the pilot light ignites but goes out as soon as you release the knob, the thermocouple is not sensing the flame. This is the most common reason a pilot will not hold. The thermocouple is a thin metal rod that sits in the pilot flame and generates a small electrical signal that tells the gas valve to stay open. If it is dirty, bent, or failing, it cannot send that signal.
The first step is to clean the thermocouple. Turn off the gas at the control knob, wait 10 minutes, then locate the thermocouple — it is the thin rod running from the pilot burner assembly into the control valve. Gently rub the end of the rod (the part in the flame) with fine steel wool or a soft cloth to remove any soot or corrosion. Do not bend it. Relight the pilot and hold the knob for the full 60 seconds. If it still goes out, the thermocouple is likely worn out and needs replacement.
Replacing a thermocouple is a straightforward job: turn off the gas, unscrew the nut holding the thermocouple to the control valve, pull it out, and screw in a new one hand-tight, then snug it with a wrench. Thermocouples are inexpensive (usually under $20) and available at hardware stores or online. If you are not comfortable doing this yourself, a technician can replace it in under an hour.
When to check the gas supply and venting
Before assuming the pilot assembly is broken, confirm that gas is actually reaching the heater. If you smell no gas odor at all near the tank, check whether the gas valve on the supply line (usually a handle on the pipe coming into the heater) is turned on. It should be parallel to the pipe; if it is perpendicular, it is off. Turn it parallel and try lighting the pilot again.
Also check that the vent pipe running from the top of the heater to the outside is clear. A blocked vent can prevent the heater from working properly and is a safety hazard. Look for any visible blockage, leaves, or debris at the vent opening on your roof or exterior wall. If the vent is blocked, clear it or call a technician to do so.
If you smell gas but the pilot will not light after several attempts, do not keep trying. Turn the control knob to "Off", turn the gas valve handle to the perpendicular (off) position, open windows and doors to ventilate, and call a licensed technician or your gas company. A persistent gas smell with no flame can indicate a leak or a faulty valve.
Tools and materials you will need
To light a pilot light, you need a lighter or long-handled match — a regular match works but a long-handled lighter or grill lighter gives you more reach and safety distance from the burner. Some people use a thin piece of rolled paper lit at the stove, though this is less reliable. Keep these items near your water heater so you do not have to search when the pilot goes out.
If the thermocouple needs cleaning, gather fine steel wool, a soft cloth, and a wrench (usually 7/16 inch or 1/2 inch, depending on your heater model). If you are replacing the thermocouple, buy a replacement that matches your heater's model number — take a photo of the old one or bring it to the store to may support you get the right fit.
How often pilot lights go out and what causes it
A pilot light that goes out once every few months is normal and usually caused by a draft, a power surge affecting the igniter, or a minor buildup of soot on the thermocouple. Relighting it is a routine maintenance task. A pilot that goes out weekly or more often suggests the thermocouple is wearing out, the gas pressure is too low, or there is a draft problem in your home.
Drafts from open windows, doors, or exhaust fans can blow out a pilot light. If your pilot goes out only on windy days or when you open a nearby window, draft is likely the cause. You can reduce drafts by closing windows and doors near the heater, ensuring the vent pipe is properly sealed, and checking that the heater closet door is not open to a cold garage or basement.
If the pilot goes out frequently and you have ruled out drafts and a dirty thermocouple, the gas pressure may be too low or the thermocouple may be failing. A technician can measure gas pressure and advise whether the valve needs adjustment or the thermocouple needs replacement.
Safety reminders when working with your water heater
Never attempt to light the pilot if you smell a strong gas odor — this can indicate a leak. Instead, turn off the gas supply, leave the area, and call your gas company or a technician. A small amount of gas smell is normal when the pilot has been out for a while, but a strong, persistent smell is a warning sign.
Keep flammable materials (paper, cloth, cleaning supplies) away from the heater and its vent. The burner and surrounding metal get hot during operation. Wear long sleeves or use a long-handled lighter to keep your hands and arms away from the flame and hot surfaces.
If you are uncomfortable working with gas appliances or if the pilot will not light after following these steps, call a licensed technician. Water heater repairs are not expensive when caught early, and a professional can diagnose problems that are not obvious to a homeowner.
Frequently Asked Questions
How long should I hold the ignition button after the pilot lights?
Hold the button for 30 to 60 seconds after the flame appears. This gives the thermocouple time to heat up and send a signal to the gas valve to stay open. If you release too soon, the pilot will go out. If you hold it longer, that is fine — just do not release before 30 seconds.
What if my water heater has no ignition button?
Older heaters without a piezo igniter require you to use a match or lighter to light the pilot. Turn the knob to "Pilot", hold a lit match near the pilot opening, and keep the knob pressed for 30 to 60 seconds after the flame catches. The process is the same; you are just providing the flame manually instead of using an electric igniter.
Can I light the pilot if the power is out?
Yes, if your heater has a manual ignition option or uses a match. Turn the knob to "Pilot" and light it with a match or lighter as usual. However, if your heater relies on an electronic igniter or control board, it will not work without power. Once power is restored, the heater should operate normally.
Is it normal for the pilot light to go out occasionally?
A pilot that goes out once every few months is normal and usually caused by a draft or minor soot buildup. A pilot that goes out weekly or more often suggests the thermocouple is wearing out or gas pressure is low. If it happens frequently, have a technician check the thermocouple and gas pressure.
What does it mean if I smell gas but the pilot won't light?
This can indicate a gas leak, a faulty valve, or a problem with the ignition system. Do not keep trying to light it. Turn off the gas, ventilate the area, and call a technician or your gas company. Persistent gas smell with no flame is a safety concern and requires professional attention.