What must the stack mount primary control be before use?

Before use, the stack mount primary control must be put in step. This step involves ensuring that the control is set correctly to monitor and manage the operation of the burner system effectively. By putting it in step, the technician initiates the control's functioning so that it can start and stop the burner based on the temperature conditions of the stack (flue gases) or other specified criteria. This is critical for safe and efficient operation because the primary control is responsible for preventing unsafe conditions, including overheating or incomplete combustion.

The process of putting the control in step allows the technician to confirm that all functions of the primary control are operational before the system is put into service. This proactive measure ensures that the burner will operate correctly and safely during normal functioning.

While recalibrating, testing for safety, or upgrading might be necessary under different circumstances, they are not the immediate steps required to prepare the stack mount primary control for use. The focus here is on ensuring that the control is ready to function properly, which is achieved by putting it in step.