What function does the stack switch/primary control perform?

The stack switch or primary control plays a critical safety role in the operation of oil burners. Specifically, it is designed to detect ignition failures. When the burner is attempting to ignite, the stack switch monitors whether combustion has occurred as expected. If the combustion chamber does not reach the desired temperature or if ignition fails entirely, the stack switch will respond by shutting down the oil burner. This feature is crucial for preventing the release of unburned fuel, which could pose a fire hazard.

The ability to shut down the burner in these situations ensures that safety is maintained, protecting both the equipment and the surrounding environment. Understanding this function is essential for operating oil burners safely and effectively, as it highlights the importance of systems designed to respond to potentially hazardous situations.