In what scenario is a boiler required to have at least two means of feed water?

A boiler is required to have at least two means of feed water primarily when it has a heating surface area exceeding 500 square feet. This regulation is in place for safety and operational reliability. In larger boilers, the risk of operational failure can have more serious consequences due to their increased capacity and the potential for significant steam generation. By ensuring that there are two independent means of supplying feed water, operators can maintain the necessary water levels even if one system fails.

This redundancy helps in preventing situations where a loss of feed water could lead to overheating or pressure buildup, which might result in equipment damage or dangerous steam explosions. Therefore, a boiler of this size must adhere to stricter safety requirements to ensure consistent operation and prevent hazards.

The other scenarios provided, while important in their own right, do not specifically mandate the need for dual feed water sources according to typical boiler safety regulations.