Waking up to a cold shower is a rough start to the day. If your water heater’s pilot light has gone out, don’t panic. Lighting a water heater is a simple job you can usually handle yourself in a few minutes, no plumber required.
This guide shows you where to find the pilot, how to light it safely on both modern sealed tanks and older units, and how to fix the real reason it went out, from a worn thermocouple to a flammable vapor lockout that stops the flame from catching at all.
Key Takeaways
- Find the pilot at the bottom of the tank, through the sight glass on a modern sealed unit or behind the access panel on an older one.
- Turn the gas knob to “Off,” wait 10 minutes for gas to clear while you smell for it near the floor, then set the knob to “Pilot” and ignite it while holding the knob down.
- Keep holding the knob for about 60 seconds after the flame lights so the thermocouple heats up, or the safety valve will cut the gas.
- A pilot that won’t stay lit is usually a dirty or failed thermocouple; a modern heater that won’t light at all may be in a flammable vapor sensor lockout that needs resetting.
Where Is the Pilot Light on My Water Heater?
To find the pilot light, look at the bottom of the tank. Its exact spot depends on how old your unit is and what style it uses.
Modern water heaters use a sealed combustion chamber with a door you cannot remove. Instead, look for a small glass viewing window, called a sight glass, and watch for the flame through it.
Older units usually have a removable metal access panel at the base. Lift or unscrew that plate to expose the burner and pilot assembly.
How to Light a Water Heater
Safety comes first. Before you reach for a lighter, get down on your hands and knees and sniff around the base of the heater. Propane is heavier than air and pools on the floor, while natural gas rises.
If you smell rotten eggs or hear a hissing sound, do not light anything. Leave the house right away and call your utility company from outside.
Take Note
Natural gas and propane are naturally odorless. Suppliers add a chemical called mercaptan to give the gas its distinct rotten egg smell, so you can detect a leak.
What You’ll Need
- Screwdriver (for access panels).
- Flashlight or headlamp.
- Wand lighter (long BBQ lighter) or extra-long matches.
Automatic Pilot Light (Piezo Igniter)
Most newer gas water heaters use a piezoelectric spark generator. This is the red or black button that clicks like a grill lighter, so you do not need an open flame for these models.
1. Prepare the Valve
Locate the gas control knob on the front of the thermostat box and turn it to the “Off” position. Wait at least five to ten minutes so any leftover gas in the combustion chamber can clear. Do not skip this step.
2. Set to Pilot
Turn the gas control knob to the “Pilot” position. On some Honeywell valves, you may need to press the knob down slightly to turn it.
3. Ignite the Flame
Hold down the gas control knob, or the separate pilot button if your model has one. While holding it down, press the igniter button firmly. You should hear a click. Look through the viewing window to see if a blue flame appears.
You may need to click the igniter several times before it catches.
4. Heat the Thermocouple
Once the flame is lit, keep holding the knob down for about 60 seconds. The pilot flame needs to warm the thermocouple sensor. If you let go too early, the safety valve trips and cuts the gas.
5. Turn the Gas Valve On
Release the knob. The pilot should stay lit. Turn the knob from “Pilot” to “On.” You will hear a “whoosh” as the main burner ignites.
Manual Pilot Light
Older tanks do not have a click-start button, so you apply a flame by hand. These units usually have a removable inner and outer access panel.
Top Tip
Use a headlamp or have a helper hold a flashlight. You need both hands free to hold the gas button and the lighter at the same time.
1. Clear the Chamber
Just like the automatic method, turn the valve to “Off” and wait 10 minutes for the gas to clear.
2. Position Your Lighter
Remove the access panels and find the pilot tube, usually a small silver tube curving up near the main burner. Turn the knob to “Pilot.”
Safety Note
Avoid standard matchsticks or cigarette lighters, since the gas can flare up suddenly. Use a long-reach wand lighter to keep your fingers well clear.
3. Light the Pilot
Press and hold the gas control knob down. Immediately apply your flame to the end of the pilot tube. It should light instantly.
4. Finish the Process
Continue holding the knob down for a full minute to warm the thermocouple. Release the knob slowly. If the flame holds, replace the access covers and turn the valve to “On.”
How to Light Hot Water Heater Without Igniter
If you have a modern heater but the red igniter button is broken, you can still light it. You treat it like a manual heater, but you have to work around the sealed chamber.
- Remove the outer door and locate the bottom of the sealed combustion chamber.
- Some units have a small port made for manual lighting, but many sealed units strictly forbid opening the combustion chamber. Check your owner’s manual first.
- If it is safe to proceed, turn the knob to “Pilot” and hold it down.
- Insert a long BBQ lighter through the designated lighting opening.
- Ignite the pilot and hold the button for 45 to 60 seconds.
- Remove the lighter, close the port or door right away, and turn the dial to “On.”
Reasons Why Your Pilot Light Goes Out
If you have to relight your heater every week, you have a deeper problem. Ignoring it can lead to total system failure. Brands like Rheem, Bradford White, and Honeywell sell replacement parts, but you need to diagnose the fault first.
Safety First
Always turn off the main gas supply valve before you attempt any repairs or part replacements.
Thermocouple Failure
The thermocouple is a safety device that senses the pilot flame. Its tip sits in the flame and generates a small voltage, around 20 to 30 millivolts, according to Roto-Rooter, that holds the gas valve open. If it doesn’t feel enough heat, it assumes the flame is out and cuts the gas to prevent a leak. A worn or dirty thermocouple is by far the most common reason a pilot won’t stay lit.
If you own a multimeter, you can confirm the part is bad by testing its output. A reading under about 20 millivolts means the thermocouple should be replaced.
Broken Thermocouple
These copper rods wear out over time. If the tip is burnt or the line is kinked, it cannot send its electrical signal to the gas valve. They are inexpensive to replace, usually in under an hour, though some sealed units make access harder.
Dirty Thermocouple
Sometimes the part is fine but coated in carbon buildup, or soot. This insulates the rod and stops it from getting hot enough. Clean it with a piece of emery cloth, fine steel wool, or even the rough surface of a dollar bill. Scrub the tip gently until you see bare metal.
Misaligned Thermocouple
The rod must sit inside the blue part of the flame. If it was bumped during cleaning, it might be too far away. Gently bend the bracket with needle-nose pliers to move the rod back into the flame’s path.
Dirty Pilot Orifice
Dust and dirt can clog the tiny opening where the gas comes out. The result is a weak, yellow flame that isn’t hot enough to trigger the thermocouple. Try blowing compressed air into the tube to clear it. A can of compressed air, such as the Falcon Dust Disposable Cleaning Duster, comes with a straw that helps you reach the tight opening.
Flammable Vapor Sensor Lockout
Gas water heaters built since 2003 are flammable vapor ignition resistant, or FVIR (1). They carry a flammable vapor sensor that watches for gasoline, paint, or solvent fumes near the unit. When it detects those vapors, it triggers a soft lockout that shuts the heater down, and the pilot will not light at all until you reset the control. If a modern heater refuses to light and you store fuel or chemicals nearby, this is a likely culprit.
To clear the lockout, first remove whatever is giving off the fumes and let the area air out. Then reset the gas control the way your manual describes, which usually means switching the control to “Off” for about 10 seconds (2), or unplugging the power on newer valves and waiting the stated time before you try again.
Clogged Air Intake
FVIR heaters pull combustion air through a screened intake, called a flame arrestor, at the base of the tank. Lint, pet hair, and dust build up on that screen and starve the flame of oxygen, which makes the pilot burn weakly or drop out. Vacuum around the base and clean the intake screen so the burner gets the air it needs.
Fluctuating Gas Supply
Sometimes the problem isn’t your equipment. During peak usage or utility maintenance, the gas pressure in the grid can drop. If it falls too low, the pilot starves and goes out. If your neighbors are having the same trouble, call your utility provider.
Improper Airflow or Drafts
A pilot light that keeps going out on windy days usually points to a venting issue. A strong downdraft through the chimney can blow the flame out. Check that the vent cap on your roof is intact and not blocked by bird nests or debris.
Faulty Gas Control Valve
If the pilot still won’t stay lit after the thermocouple tests good and the parts are clean, the gas control valve itself may be at fault. A one-time thermal cutoff inside the unit can also trip and lock it down after an overheat, and it generally has to be replaced, though some makers offer a reset or repair kit under warranty. At this stage, a licensed plumber is the safe call.
FAQs
Don’t Let the Pilot Light Go Out on You
Relighting a water heater is a basic skill every homeowner should know. It saves you a service call and gets your hot water running again in minutes. But if you find yourself back on your knees every few days, stop and find the cause instead of just relighting.
Whether it turns out to be a quick cleaning, a new thermocouple, or a vapor sensor that needs resetting, fixing the root cause beats constant babysitting. Check for leaks, work slowly, and get back to that hot shower.
