Why a Water Heater Pilot Light Will Not Stay Lit
A pilot that lights, then dies when you release the knob is one of the most common gas water heater faults. The cause is usually a small part, but it sits next to a gas valve, so safety comes first.
Call (720) 794-0054Safety first
- If you smell gas, leave and call the gas company from outside.
- Do not use matches, lighters or switches if you smell gas.
- Follow the lighting label on the tank.
- Never hold the knob down longer than the label says.
- Stop and call if the flame is yellow or lifts off the burner.
How a standing pilot works
A standing pilot is a small flame that stays lit. It heats a sensor called a thermocouple. While the sensor is hot, it holds the gas valve open. If the flame goes out, the sensor cools and the valve closes.
When you hold the knob down, you override the valve until the thermocouple warms. A pilot that dies when you let go means the sensor is not holding the valve open.
Common causes
Why the pilot keeps going out
| Cause | What happens | Fix |
|---|---|---|
| Worn thermocouple | Does not hold the valve open | Replace the part |
| Dirty pilot tube or orifice | Weak flame that cannot heat the sensor | Clean it |
| Draft or blocked air supply | Flame blows out or flickers | Check venting and the room |
| Failing gas control valve | Valve will not stay open | Replace the valve |
| Low gas supply | Flame is small or erratic | Check the supply valve |
Pilot keeps going out?
Call and share the age and model of the heater. The dispatcher will plan the visit.
What to look at
Look through the sight glass if the heater has one. A steady blue flame that wraps the thermocouple is healthy. A tiny or yellow flame is not. Check that the gas supply valve near the heater is open and that nothing is stored against the unit. Dust and lint can restrict air. Keep the area clear.
Newer heaters have no pilot
Many newer water heaters use electronic ignition or sealed combustion. There is no standing flame to relight. The fault shows up as an error light or no heat. The fix can involve a sensor, an igniter or the control board.
The data plate on the tank names the model. Share it with the dispatcher so the right parts come on the truck.
When to stop and call
Call if the pilot goes out again after a clean relight. Call if the flame is yellow, the burner smells or soot appears on the tank. Call if you cannot find the cause in a few minutes. A technician tests the thermocouple, cleans the pilot assembly, checks the venting and tests for gas leaks. The water heater repair page explains a visit.
Repair, or time for a new heater
A thermocouple is a small repair. A failed gas valve or a tank that is leaking at the bottom is a larger question. An older heater with several faults may be better replaced. Ask the plumber to price both repair and replacement. The replacement page explains sizing, venting and permits.
What a relight usually involves
The steps are on the label on the tank, and the label is the guide. In general you turn the control to the pilot setting, hold it down, press the igniter and keep holding for the time the label gives.
Release the knob slowly. If the pilot stays lit, turn the control to the on setting. If it dies each time, stop. Repeating the same steps only wastes time.
Altitude and combustion
Brighton sits at about 4,987 feet. Thinner air can affect combustion in a gas appliance. If a unit is replaced, ask the plumber whether it is suited to the local altitude. A flame that is yellow or lazy may point to an air or fuel problem. That is a reason to call, not to keep relighting.
Carbon monoxide and venting
- Keep a working carbon monoxide alarm near sleeping areas.
- Check that the vent pipe is connected and slopes upward.
- Look for rust streaks or soot on the vent.
- Keep the area around the heater clear.
- Switch the heater off and call if you see soot or smell exhaust.
Keep the pilot area clean
Dust and lint collect around the burner and the pilot tube. A heater in a laundry room or garage collects more. Cleaning is a job for a technician, because the parts sit next to the gas valve. If the heater is in a closet, make sure the door louvers or openings are not blocked. A heater needs air to burn well.
Why a pilot fails after a long idle
A heater in a vacant house or a seasonal property may sit unused for months. Dust and spider webs can block the pilot tube. The pilot may light and then fail when the sensor has lost its edge. If a heater has been off for a while, have it checked before you rely on it. A quick look at the burner and venting is easier before the first cold night.
Signs the thermocouple is wearing out
- The pilot lights, then dies a few seconds after you release the knob.
- The pilot burns weakly or flickers.
- The tip of the sensor looks dark or sooty.
- The heater has needed several relights in a month.
These are common signs, and a technician confirms the cause with a quick test.
Planning for the next failure
If a heater is more than a decade old, note its age and keep the paperwork. Ask the plumber what a replacement involves, so you know your options before the tank leaks. A planned replacement avoids a cold shower on a winter morning, and it lets you compare unit types.
Gas line and venting concerns
If the pilot fault comes with a gas smell, the gas supply may be the problem, not the heater. Gas piping is a separate repair. See gas line repair and installation.
Quick answers
Only if there is no gas smell and you follow the label on the tank. If in doubt, call.
The thermocouple is not warming or not holding the valve open. It is often a worn part.
A draft down the vent or air from a door can. Check the room and venting.
Ask the dispatcher for a quote before work starts. It depends on the heater and access.
Look for an error light and share the model with the dispatcher.
Gas water heater not staying lit?
Call and describe the flame, the model and what the heater does.