How to Relight a Water Heater Pilot Light Safely
How to relight a water heater pilot light safely: check for gas first, follow the label, and learn why a pilot will not stay lit and when to call for help.
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How to relight a water heater pilot light takes about ten minutes, but only after you have checked there is no smell of gas. If you smell gas, do not light anything: leave and call the gas utility from outside. If the air is clear, follow the lighting instructions printed on your heater, because the control knob layout differs between models.
How to relight a water heater pilot light: safety first
Gas water heaters with a standing pilot keep a small flame lit all the time. When it goes out, the gas supply to the burner shuts off, and you get no hot water. Before you do anything, check three things.
- No gas smell. Natural gas has a sulfur odour added. If you smell it, leave, and do not use switches, phones or flames inside.
- No flammable fumes. Do not light a heater in a room where petrol, solvents or paint are stored.
- The label. Every heater has lighting instructions on it. Follow those over any general guide.
| Quick facts: how to relight a water heater pilot light | |
|---|---|
| Time needed | About 10 minutes, plus 5 minutes waiting for gas to clear |
| Tools | Long butane lighter or the heater's igniter button, flashlight |
| Difficulty | Easy, if there is no gas smell |
| Stop and call if | You smell gas, the flame is yellow or sooty, or the pilot will not stay lit |
Typical steps for a standing pilot
The exact order varies by model, so treat this as an outline of what your label will say.
- Turn the gas control knob to OFF and wait at least five minutes so any gas can clear.
- Remove the burner access cover if your model has one, and find the pilot opening.
- Turn the knob to PILOT and press and hold the red pilot button.
- Light the pilot with the built-in igniter button, or a long lighter held at the pilot tube.
- Keep holding the button for 30 to 60 seconds after the pilot lights. This warms the safety sensor.
- Release the button. The pilot should stay lit. If it goes out, wait five minutes and try again.
- Turn the knob to ON and set the temperature. Replace the cover.
Why the pilot will not stay lit
| Cause | What it means | What helps |
|---|---|---|
| Worn thermocouple | The safety sensor does not detect heat | Replacement by a plumber or technician |
| Dirty pilot opening | Soot or dust blocks the flame | Clean gently per the manual |
| Draft or poor ventilation | Air blows the flame out | Close nearby openings; check venting |
| Weak gas supply | Low pressure to the heater | Call the gas utility or a technician |
| Failing gas control valve | The valve will not hold gas | Replace the control, by a professional |
Heaters with electronic ignition
Many newer heaters have no standing pilot. They light the burner with an electric igniter or a hot-surface element. These show an indicator light or error code on the control panel, and the fix is different from learning how to relight a water heater pilot light. Check the manual for the code and do not try to bypass safety parts.
Warning signs that mean stop
- A yellow or orange, sooty or wavering flame, which can mean poor combustion.
- A carbon monoxide alarm sounding. Leave and call for help.
- Soot marks around the heater or the flue.
- A pilot that needs relighting again and again.
What the pilot flame should look like
A healthy pilot is a small, steady, mostly blue flame that touches the tip of the thermocouple. A flame that is tiny, wavering or lifting away from the sensor will not keep the safety valve open. A yellow tip suggests dust or poor air supply. Check the label for a pilot adjustment screw, and adjust only if the manual says to. Anything beyond that, or any smell of gas, is a technician's job.
Prevention
Have a gas water heater inspected during routine service, keep the area around it clear, and make sure the venting is unobstructed. A carbon monoxide alarm near any gas appliance is a sensible precaution.
Related reading
- How to Reset a Water Heater: Electric, Gas and Tankless
- How Long Does a Water Heater Last? Lifespan and Warning Signs
- Water Heater Popping Noise: Why It Happens and How to Stop It
- Gas Oven Won't Light? Safe Checks and When to Call a Technician
Browse all plumbing guides, or find a plumber in your city from the plumbing directory.
Frequently asked questions
How to relight a water heater pilot light if there is a gas smell?
Do not relight it. Leave the house, avoid switches and phones indoors, and call the gas utility or emergency services from outside. Only relight after the source has been found and the air has cleared completely.
Why does my water heater pilot light keep going out?
The usual causes are a worn thermocouple, a dirty pilot opening, a draft that blows the flame out, or low gas pressure. A pilot that will not stay lit after two tries needs a technician rather than more attempts.
How long do I hold the pilot button when relighting?
Hold it for about 30 to 60 seconds after the flame appears. This warms the thermocouple so it tells the gas valve to stay open. If the flame goes out when you release it, wait and retry once.
Is it safe to relight a water heater pilot light myself?
Usually yes, when there is no gas smell and you follow the label on your heater. If you are unsure, the flame is yellow, or the pilot keeps going out, a plumber or gas technician is the safer choice.
What is a thermocouple on a water heater?
It is a safety sensor that sits in the pilot flame. When it is hot it keeps the gas valve open, and when the flame goes out it closes the valve. A weak or dirty one makes the pilot drop out.
Why is my water heater not heating even though the pilot is lit?
The pilot may be lit but the burner not firing. Possible causes are a thermostat set too low, a failed gas control, a clogged burner, or a tripped limit switch. The gas control or burner usually needs professional repair.
What does a yellow pilot flame mean?
A healthy flame is mostly blue. A yellow or orange flame can mean poor combustion, a dirty burner, or a ventilation problem, which can produce carbon monoxide. Turn the heater off and call a technician to inspect it.
When should I call a plumber for a pilot light problem?
Call if you smell gas, the pilot will not stay lit, the flame looks wrong, you see soot, or a carbon monoxide alarm sounds. These point to a fault that is unsafe to troubleshoot on your own.
Why does the pilot light keep going out?
A dirty pilot tube, weak thermocouple, drafts or a faulty gas valve. Cleaning the pilot assembly or replacing the thermocouple often fixes it. If cleaning does not help, a new thermocouple is an inexpensive part, but call a professional if you smell gas.
Is a pilot light the same as an electronic ignition?
No. Older gas heaters use a standing pilot flame, while newer ones use an electronic igniter that lights the burner only when needed, with no pilot to relight. The manual or the label on the heater tells you which type you have and how to light it safely.
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