Final answer:
To configure the low pressure control as desired, the technician should set the 'high event' to 28 psig and the 'differential' to 26 psig.
Step-by-step explanation:
The student is inquiring about the correct settings for a low pressure control that has a 'high event' and a 'differential' setting. To ensure that the system turns on at 28 psig and shuts down at 2 psig, the technician must set the 'high event' or cut-in to 28 psig and the 'differential' to 26 psig. The differential is the difference between the cut-in and cut-out pressures.
To calculate the differential, you subtract the cut-out pressure from the cut-in pressure (28 psig - 2 psig = 26 psig). These settings will allow the system to activate when the pressure reaches 28 psig and to stop when the pressure drops to 2 psig, which is what the technician wants to achieve.