👉 Overdraining is a process in which water is drained from a boiler or other closed system, typically resulting in a reduction in pressure and temperature. This operation is often used to cool down an object, such as a furnace or a steam generator, by reducing the amount of heat generated during combustion. Overdraining can be accomplished through various methods, including removing the lid or venting the system, which allows the air to escape while still allowing a small volume of steam to flow back into the system