How Does a Pilot Light Work?

Pilot lights control gas flow to make appliances safer.

Pilot lights control gas flow to make appliances safer.

Though the exact method of operation of the pilot light has changed through the years, its purpose has always been to keep gas appliances running safely. Pilot lights are found on all types of gas appliances, including stoves, water heaters and fireplaces.

Standing Pilot Light System

A standing pilot light is on all the time. The flame goes out only if there is a problem, preventing the appliance from turning on until the issue is resolved. A small amount of gas is fed continuously through a tube to create a tiny flame. This flame gets larger when the appliance is turned on, heating the bulb of a safety valve that then opens to allow more gas into the appliance while it is in use. Standing pilot lights once had the potential to create a dangerous situation if the pilot light went out but the gas feeding it continued to flow, building up inside the appliance. Appliances now are fitted with thermocouples that stop the gas flow to the pilot light if it goes out.

Electric Ignition Pilot Operation

In an electric ignition system, an electrical circuit is completed when the appliance is turned on via a switch or thermostat. The completion of the circuit turns on an electric heating element. When the element reaches a certain temperature, gas flows into the system where it is ignited by the hot element. The gas stops flowing when the electrical circuit is broken by turning off the appliance. This system is more efficient as it requires gas to run through only when it's operating.

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