What is a Pilot Light?

Ken Black

A pilot light is a small flame that is kept lit to provide a catalyst for a much larger flame when it is called upon to do so. These lights are common in home appliances that use natural gas or petroleum, such as central heating furnaces, water heaters and even older stoves. They are also found on hot air balloons.

Many gas appliances have electric igniters to light the burners.
Many gas appliances have electric igniters to light the burners.

The way that a pilot light usually works is by maintaining a permanent flame at a very low level. It may glow blue in many cases. As more fuel is added to the mixture, the flame will ignite other burners and create a fire capable of doing a specific job, such as heating water or air, or cooking. Even once those burners are turned off, the pilot remains on.

Gas furnaces typically have a pilot light.
Gas furnaces typically have a pilot light.

Although this flame is meant to stay on a majority of the time, there may be times when it is extinguished, either on purpose or accident. While reigniting a pilot is not a big ordeal, careful attention should be taken to light it exactly as specified in the directions. Otherwise, it could become dangerous.

Hot air balloons have pilot lights.
Hot air balloons have pilot lights.

In the summer months, when a gas furnace is no longer being used, some people may choose to shut down the pilot light. This is a personal choice and will obviously save some money on the consumption of natural gas or other types of fuel used for the furnace. There is usually a valve that will squelch the fuel to the flame, effectively extinguishing it. Given that some estimates say the fuel consumption by the pilot can represent 50% of the appliance’s fuel consumption, extinguishing the flame may be good way to save some money during long periods of dormancy.

A pilot light will ensure the functionality of a natural gas appliance such as a water heater or gas range even if the electricity goes out. Some gas appliances are moving away from the use of these flames, however, and they now depend on electrical ignition. They may still be able to be lit with a match if electricity is unavailable, but this is generally not advisable.

If the flame does get extinguished accidentally, there are safety features included on appliances that should stop the flow of natural gas as well. A thermocouple will sense that the flame is no longer lit and take appropriate actions by automatically shutting a valve, even if no electricity is available. If the gas were allowed to continue into the system without being burned, it could easily fill the room or home, causing a risk of explosion or asphyxiation to any inhabitants.

Natural gas appliances, such as stoves and water heaters, have a pilot light.
Natural gas appliances, such as stoves and water heaters, have a pilot light.

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Discussion Comments


Yeah, John57's method is a way to die of carbon monoxide poisoning, as well as inhale a lot of combustion products in the air.

But I get it, you had to do what you had to do. Just don't seal up a room *too* well and try this...


I called the pilot light on our gas heater in the living room the “fireplace light” when I was little. It seemed dangerous to me that there was always a little flame burning, but my parents said it was safe.

However, a time or two, the flames would flare out of control when they would first come on. Instead of just slowly heating up the cylinders, for some reason, the pilot light would flare up and make a terrible roaring noise. The only way to stop it was to turn the thermostat way down.

So, I became afraid of the fireplace light after this happened. We eventually switched to central heat and air, and I felt much safer.


Last fall when it got cool enough to run the heater, our furnace wouldn't come on. The first thing they asked me when I called the repair man was if the furnace light was on or not.

Not knowing much about how a furnace works, I didn't even know where to look for the light. Come to find out it wouldn't have mattered anyway, because we had to replace the whole furnace.

At least I learned a little something about how a furnace works. If I ever have trouble again, this will be the first thing I look for.


I used to live in a house where the pilot light on the hot water heater would blow out on windy days.

This was so frustrating because you wouldn't even realize it until you were ready to take a shower, and all you had was cold water.

We would have to re-light the pilot light to get the water heater going again. It usually took at least 20-30 minutes for the water in the tank to get warm again.


We used to have an old gas stove that had a pilot light. Sometimes in the middle of winter we would lose electricity for a few days, and we would use the warmth of this stove to keep warm.

We would block off the kitchen area and keep the stove running on low. All of us stayed in this one room of the house until the electricity came back on.

I am sure this is not something that is recommended, but we lived out in the country, and this is just what we did to survive those days without electricity.

As long as the pilot light stayed lit, and we didn't run out of gas, we knew we would have some heat and be able to cook some food.

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