Gas appliances, like stoves, furnaces, water heaters, and even dryers, generate heat by burning natural gas, propane, or another alternative fuel. Furnaces use this heat to warm up the house, water heaters heat the water in the tank, and dryers heat the clothes as they tumble around inside the drum. Stovetops and ovens also rely on this heat source to cook and bake.

For these gas appliances to operate effectively, they use a small pilot light that acts as an ignition source for the gas. While many modern gas appliances have electric starters or ignitors, older appliances typically have a standing pilot light that needs to remain lit for the appliance to generate heat.

If the pilot light goes out, the appliance won't function properly and gas could gradually build up in the home, so it's important to learn how to light a pilot light to restore the normal function of the appliance. Use this guide to find out more about how a pilot light functions, what causes it to go out, and how to safely light it if necessary.

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What Is a Pilot Light?

A pilot light is a small blue flame in a gas-burning appliance that is fueled by a small amount of gas. Pilot lights are used as an ignition source for larger burners inside furnaces, stoves, water heaters, clothes dryers, ovens, and gas fireplaces. Standing pilot lights are common in older appliances that are not equipped with electronic ignition switches, but if the pilot light goes out then the burners won't ignite and the appliance will not function properly.

For instance, in a furnace the pilot light ignites a larger burner at the beginning of a heating cycle, then the heat produced by the burner is distributed throughout the home by an internal fan and a series of ducts and vents. Similarly, the pilot light in a gas water heater ignites a burner when the temperature of the water inside the tank drop below a certain threshold. The heat from the burner increases the temperature of the water to the set temperature before shutting off.

This flame may go out as a result of an errant draft, dirty valve, or faulty thermocouple (the safety device that shuts off the gas to an appliance when it detects that the flame has gone out).

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When Would I Need to Light a Pilot Light?

Homeowners only need to worry about lighting a pilot light if it happens to go out. Pilot lights may be extinguished by a strong breeze, like the wind generated when someone closes a door too hard. Open windows, open doors, and drafty basements or crawlspaces may also produce enough of a breeze to blow out a pilot light.

Pilot lights can also go out if the gas valve is dirty, clogged, or damaged. Additionally, the pilot light can be extinguished by a faulty thermocouple. A thermocouple is a safety device intended to cut off the flow of gas if the pilot goes out, but if this component is not functioning properly, it may shut off the gas while the pilot light is still ignited, extinguishing the flame. If you suspect a problem with the gas valve or thermocouple, shut off the gas to the appliance and hire a professional to inspect and repair the issue.

What You'll Need

Equipment / Tools

• Screwdriver
• Flashlight
• Long-handled lighter

Materials

• Long matches

Instructions

How To Safely Light a Pilot Light

Check the User Manual to Locate the Pilot Light

1. The easiest way to find the pilot light is to refer to the user manual that came with the appliance. The manual will also provide important safety warnings and steps for how to light the pilot light on the specific make and model of appliance.
2. On a furnace, the pilot light is usually located near the bottom. Similarly, the pilot light for an over is also often at the bottom, while on a water heater it's typically covered by an access panel that you will need to remove with a screwdriver. Four-burner stovetops will typically have central pilot light ports under the stovetop lid located on at the left and right side of the stove.

Turn Off the Gas

1. Typically, a gas furnace or gas water heater will have a simple switch with settings marked "off", "on", and "pilot". When a pilot light goes out, gas can seep out into the home, so before you attempt to reignite the pilot light, turn off the gas and wait about five to 10 minutes for any residual gas to clear. 
2. If the appliance does not have an electric pilot light ignitor, then you don't need electricity to relight the pilot light, so you can turn the appliance off at the breaker or at the thermostat. But if the appliance does has an electric pilot light ignitor, you will need to keep the appliance on for the ignitor to work properly.

Light the Pilot Light

1. After the gas has had enough time to clear, turn the appliance to the "pilot" setting. On newer appliances with an electric pilot light ignitor you should be able to relight the pilot light by pressing and holding the red reset button for about a minute.
2. On older appliances that do not have an electric pilot light ignitor, you will need to light the pilot light manually. Press and hold down the red reset button, then at the same time use a long-handled lighter or a long match to safely reignite the pilot light. Release the reset button once the pilot light catches flame, then observe the pilot light for a few minutes to ensure it remain lit.
3. If the pilot light goes out immediately or goes out after a few seconds, then there is likely a problem with the components of the appliance. Turn off the gas and contact a trained professional to address the issue.
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Turn the Appliance Back On

1. When the pilot light is burning consistently, you can switch the setting to "on". If you turned off the appliance at the breaker or thermostat, you can now turn it back on to restore electricity to the appliance. It's also worth checking the area around the appliance for open windows, doors, or other sources of drafts that may have caused the pilot light to go out, so you can take action to prevent this from happening in the future.

Pilot Light Safety Tips

Since gas appliances need a readily available source of gas and a flame to function, it's necessary to take appropriate safety precautions when working with these appliances. Consider these straightforward safety tips when relighting a pilot light.

• Always read and follow the directions and safety warnings provided by the manufacturer.
• If at any point you smell gas, turn off the gas valve and leave the home immediately. When you get outside, call the local gas company or emergency service for help dealing with the situation.
• For appliances with a ventilation fan, make sure the fan is on while lighting the pilot light.
• Pilot lights don't always ignite the first time you try, so if the gas is one for several seconds while lighting the pilot it's recommended to turn off the gas for a few minutes to let the gas clear, then you can try to light the pilot light again.
• When the pilot light will not relight after several attempts, the problem may be due to faulty or damaged components. Shut off the gas and call a licensed technician to assess and repair the issue.