Why is it important to purge a boiler before starting the auxiliary burners?

Purging a boiler before starting the auxiliary burners is crucial primarily for safety reasons, which is why the focus on removing possible combustible gases is essential. When a boiler has not been in operation for a while, there might be unburned fuel or flammable gases present in the combustion chamber or piping. Purging helps to eliminate these dangerous gases, mitigating the risk of an explosion or fire upon ignition of the burners.

This preventative measure ensures that only clean air enters the system, allowing for a safe start-up. While improving efficiency, removing water, or cleaning the burner assembly are important maintenance tasks in their own right, they do not directly address the immediate safety concerns associated with the presence of combustible gases. Therefore, the primary rationale for purging is the need to protect personnel and equipment from the hazards of combustion that could result from leftover gases.