The basic steps to relight your pilot

To turn on a gas heater pilot light, you need to locate the control knob (usually labeled "Pilot," "On," and "Off"), set it to the pilot position, press and hold it down, and use a long lighter or match to ignite the gas at the small opening near the knob. Hold the knob down for 30 to 60 seconds after the flame appears so the thermocouple — a heat-sensing device — can warm up and keep the gas flowing. Then turn the knob to "On" and listen for the main burner to ignite.

The whole process takes about two minutes. If the pilot won't stay lit after you release the knob, the thermocouple may be dirty or failing, or the gas supply itself may be interrupted. If you smell gas at any point, stop when ready, leave the area, and call your gas company's emergency line.

Key Takeaways

  • The control knob has three positions: "Pilot," "On," and "Off" — start by turning it to "Pilot."
  • You must press and hold the knob while lighting the pilot flame with a long lighter or match held near the ignition opening.
  • Keep the knob pressed for 30 to 60 seconds after ignition so the thermocouple can sense the heat and lock the gas valve open.
  • If the pilot light goes out when ready after you release the knob, the thermocouple is likely worn out and needs replacement.
  • A strong gas smell means stop and call your gas company — do not attempt to relight.

Where to find the control knob and pilot opening

The control knob is mounted on the front or side of the heater's burner box, usually near the bottom. It is a round dial with three labeled positions. Below or beside the knob, you will see a small metal tube or opening — this is where the pilot flame burns. Some heaters have a window so you can see the pilot flame; others do not.

Before you touch anything, turn off the heater at the thermostat and wait five minutes. This clears any unburned gas from the chamber. Then locate the gas shutoff valve on the supply line leading to the heater. It looks like a small lever or ball valve. You do not need to close it for a normal pilot relight, but knowing where it is matters if you smell gas.

Lighting the pilot step by step

Turn the control knob all the way to "Pilot." You will hear a faint hiss as gas begins to flow to the pilot opening. Now press the knob down firmly — it should click or feel like it is being held in place by a spring. Do not release it yet.

While holding the knob down, bring a long lighter or long match to the pilot opening. The flame should ignite when ready. If it does not light after three or four attempts, release the knob, wait 30 seconds, and try again. Repeated failed ignition means gas is building up in the chamber, and you need to let it clear.

Once the pilot flame is burning, keep the knob pressed down for another 30 to 60 seconds. This allows the thermocouple to warm up and signal the gas valve to stay open. After the time has passed, slowly release the knob. The pilot flame should remain lit. If it goes out, press the knob down again and hold it for a full 60 seconds before releasing.

Turning the heater back on

Once the pilot is holding steady, turn the control knob from "Pilot" to "On." You should hear the main burner ignite within a few seconds, and the heater will begin producing heat. If the main burner does not light, turn the knob back to "Off," wait one minute, and try again.

Set your thermostat to your desired temperature. The heater will now cycle on and off as needed to maintain that temperature. If the pilot light goes out again within the next hour, turn off the heater and do not attempt to relight it — this usually signals a thermocouple problem that requires a technician.

Why the pilot light goes out

A pilot light that will not stay lit almost always points to a faulty thermocouple. This device sits in the pilot flame and generates a small electrical signal that tells the gas valve to open. When it fails, the valve closes automatically as a safety measure, and the pilot goes out. Replacement thermocouples cost between $15 and $40 and take 10 to 20 minutes to swap out if you are comfortable with basic tools.

A draft or strong air current can also blow out the pilot, especially in older heaters without a protective shield. If your pilot keeps going out only on windy days, check for gaps around the heater or ductwork that might be letting cold air in. A clogged pilot opening — caused by dust or debris — will produce a weak flame that struggles to stay lit. In that case, you may need to clean the opening with a thin wire or compressed air.

Safety checks before you start

Before lighting the pilot, make sure the area around the heater is clear of clutter, paper, and anything flammable. Check that the heater itself is not leaking water or showing visible damage. If you see rust, corrosion, or cracks in the metal casing, do not attempt to relight the pilot — call a technician instead.

If you smell gas anywhere in your home, do not light the pilot. Leave the house, go to a neighbor's, and call your gas company's emergency number. Do not use your phone inside the house, do not flip light switches, and do not start your car in the garage. A gas leak is a serious hazard and requires professional help.

When to call a technician instead

If the pilot light will not stay lit after you hold the knob for a full 60 seconds, the thermocouple needs replacement. If you smell gas but cannot find a visible leak, call your gas company. If the heater makes unusual noises, produces a yellow or orange flame instead of blue, or shuts down repeatedly, stop using it and contact a technician. These are signs of a problem that goes beyond a straightforward pilot relight.

A service call typically costs $100 to $200 for diagnosis and repair. If your heater is more than 15 years old and needs frequent repairs, it may be cheaper to replace it than to keep fixing it. A new gas heater runs $1,500 to $3,500 installed, depending on the size and type.

Frequently Asked Questions

How long should I hold the knob down after lighting the pilot?

Hold it for 30 to 60 seconds. The longer you hold it, the more time the thermocouple has to warm up and signal the gas valve to stay open. If the pilot goes out when ready after you release it, try again and hold for the full 60 seconds.

What if I can't see the pilot flame?

Some heaters have a viewing window; others do not. If you cannot see it, listen for the hiss of gas and feel near the opening for warmth after you light it. If you hear the hiss but feel no heat, the lighter or match may not have reached the opening — try again with a longer lighter.

Is it safe to relight the pilot myself?

Yes, relighting a pilot is a normal maintenance task and is safe if you follow the steps and stop when ready if you smell gas. If you are uncomfortable with it or the pilot will not stay lit, call a technician rather than trying repeatedly.

Can a pilot light stay on all the time?

Yes. In older heaters, the pilot burns continuously. In newer models, the pilot may shut off when the heater is not in use to save gas. Check your heater's manual to see which type you have.

What does a blue pilot flame mean versus orange or yellow?

Blue means the flame is burning cleanly and efficiently. Orange or yellow flames usually mean incomplete combustion, often caused by a dirty burner or air intake. If your pilot flame is not blue, have a technician inspect the heater.