What is the function of the solenoid in a type 4 system when entering the loop flush mode?

In a type 4 system, the function of the solenoid when entering loop flush mode is to open the main flush valve by de-energizing. Understanding the mechanics of the system is key to grasping why this option is correct.

The solenoid acts as a control mechanism in the plumbing system. When the solenoid is energized, it typically holds the associated valve in a closed position. Conversely, when the solenoid is de-energized, it allows the valve to open. This is crucial during the loop flush mode, as the system needs to effectively drain or flush out contaminants and ensure proper maintenance.

By allowing the main flush valve to open when the solenoid is de-energized, the system can enable the necessary flow of fluid that facilitates the flushing process, thereby maintaining system efficiency and preventing potential blockages or buildup within the loop. Hence, choosing this option highlights an important operational functionality of the solenoid in maintaining the integrity of the system during flushing operations.