What must be done prior to the initial light-off of an idle boiler to prevent flareback?

Prior to the initial light-off of an idle boiler, it is essential to purge the furnace of combustible vapors. This step is critical because gases or vapors that may have accumulated in the furnace during the idle period can pose a significant explosion risk if ignited. Purging involves forcing fresh air through the furnace to remove these potentially dangerous vapors before introducing the fuel and igniting the flame.

This process helps to ensure a safe operational environment by eliminating any combustible mixtures that could lead to flareback — a situation where the flame unexpectedly returns into the fuel supply or the boiler itself, which can result in damage or catastrophic failure. Ensuring that the furnace is free from flammable materials before firing it up is a fundamental safety precaution in boiler operations.