Which component is critical to prevent a boiler from running dry?

The low water cut-off is a crucial component in preventing a boiler from running dry. This device monitors the water level within the boiler and is designed to automatically shut off the burner or heating source if the water level drops below a certain point. Running a boiler with insufficient water can lead to overheating, equipment damage, and even catastrophic failure, such as boiler explosions.

The low water cut-off serves a safety function by ensuring that the boiler always has enough water to operate safely. When the water level falls to a predetermined low point, the cut-off activates, which prevents further heat from being generated and protects the boiler from damage.

The other components play different roles in boiler operation and safety but do not specifically prevent the boiler from running dry in the same direct manner as the low water cut-off. For example, the pressure relief valve is designed to release excess pressure to prevent overpressure conditions, the automatic feeder adds water to the boiler but relies on the low water cut-off's input to know when to feed, and the gauge glass allows operators to visually monitor the water level but does not take action automatically.