What is lit with each cycle of a furnace that uses an intermittent pilot?

In a furnace that uses an intermittent pilot system, the pilot light is ignited with each cycle of the furnace. This type of system is designed for efficiency and safety; it only ignites the pilot when there is a demand for heat.

When the thermostat signals for heat, the control system initiates the ignition process whereby the intermittent pilot is lit. Once the pilot is established, it is used to ignite the main burner. This method ensures that fuel is not wasted by keeping the pilot lit continuously when there is no heating requirement, which is typical in standing pilot systems.

The main burner does not light unless the pilot is functioning correctly, and the flame sensor ensures that a flame is present once the burner is ignited. The ignition transformer is responsible for generating the high voltage spark needed to start the pilot, but it operates in conjunction with the pilot light rather than being lit itself each cycle. Therefore, the key component that is specifically lit at each cycle is the pilot.