The purpose of a pilot light is to ignite the gas when your furnace turns on that will then power the gas burner. The pilot light is perpetually lit by allowing a small amount of gas to come up through a gas pipe into a tube. However, the safety problem comes from the fact that if your pilot light ever blew out, gas would keep coming through, filling your home. This gas could ignite and cause an explosion.
Luckily, a very small pilot light sensor, called the “thermocouple,” was invented and installed on furnaces. This thermocouple generates electricity from the heat of the pilot light. When the pilot light goes out, the thermocouple, which is attached to a valve, loses heat and shuts the valve it is attached to. To relight the pilot light, you have to manually do so. You have to light the pilot and then wait for the thermocouple to heat up and then you can let go of the button.
Because a constantly running pilot light wastes gas, modern furnaces use something called a piezoelectric spark to light the burner instead. This is how push-button igniters work. Certain natural crystals like quartz can create a voltage when hit. Similar to a spark plug, this pressure generates a spark that then ignites the gas.
A faulty pilot light could be a broken or loose thermocouple or a clogging around the pilot light, such as a piece of wiring in the way. The setting could be off as well. Either way, a professional furnace repair technician in Fort Worth will need to take a look, such as Arthur Hagar.