In a furnace that uses an intermittent pilot, how is the pilot lit?

In a furnace equipped with an intermittent pilot, the pilot light is ignited at each cycle of the furnace. This type of system is designed to improve energy efficiency by not keeping the pilot light continuously lit. Instead, the pilot light only ignites when there is a demand for heat, which is triggered by a thermostat signal.

When the thermostat calls for heat, the control system activates a spark ignition system or a hot surface ignitor to light the pilot, allowing it to subsequently ignite the main burners when the pilot achieves a stable flame. This operation reduces wasted gas and increases overall efficiency compared to systems with a continuously lit pilot, as the pilot only operates when needed.

The other options describe scenarios that do not accurately represent how an intermittent pilot furnace functions, as they suggest a continuous operation or one-time lighting that does not align with the intermittent nature of this system.