Where should the high limit control of a steam heating boiler operate?

The high limit control of a steam heating boiler is designed to ensure the safe operation of the system by shutting the boiler down if the pressure exceeds a predetermined threshold. This threshold is typically set between the operating control and the safety valve set pressures.

By being positioned in this range, the high limit control provides a buffer that prevents the boiler from reaching a dangerously high pressure where it could pose a risk of failure or safety hazard. The operating control maintains the regular functioning pressure of the boiler, while the safety valve is set to open at a pressure that is considered the maximum safe operating limit. Therefore, the high limit control set between these two pressures functions to protect the system and allow safe operation without risking pressure excursions that might lead to damage or accidents.

This configuration ensures that the boiler operates efficiently and safely, adhering to pressure limits while avoiding situations that could lead to excessive pressure scenarios requiring the safety valve to activate. Thus, the operational integrity of the boiler is maintained, which is critical for safe and effective steam heating.