How long is the trial period before a lockout switch is energized if the pilot fails to ignite?

The trial period before a lockout switch is energized in the event of a pilot failure is typically set for 15 to 30 seconds. This duration is standard as it allows sufficient time for the existing gas to clear from the combustion chamber and for any residual gas to dissipate, ensuring safety before the system attempts to relight.

Setting the trial period within this range balances the need for safety with operational efficiency. If the pilot fails to ignite within this timeframe, the lockout mechanism will engage, preventing unsafe conditions such as gas accumulation, which could lead to hazardous situations if a subsequent ignition was attempted.

This explanation highlights the intent behind the timing and the engineering principles of safety and reliability in boiler or heating system operations.