Which component is critical for preventing overheating in a boiler?

A low water cut-off is critical for preventing overheating in a boiler because it serves as a safety device that monitors the water level within the boiler. When the water level drops below a certain point, the low water cut-off automatically cuts off the burner or heat source. This is important because if the water level becomes too low, it can lead to overheating and potentially severe damage to the boiler or a catastrophic failure due to loss of coolant in the system. Therefore, maintaining an appropriate water level is essential for safe boiler operation, making the low water cut-off a vital component for preventing overheating.

In contrast, other components play different roles; for instance, a feedwater heater is primarily used to warm the water before it enters the boiler, thereby increasing efficiency but not directly preventing overheating. A pressure gauge provides information about the pressure in the system, which is important for monitoring but does not control water levels. A blower fan is used for combustion air supply or maintaining draft, which is essential for efficient combustion, but it does not address the issue of water level directly.