How can I limit the min output % & max output % value for the PID
The PID is fixed and varies from 0 to 100% but you can write a small program that will limit the output itself.
10 DAMPER = MAX( 30 , PID1 )
In this example the damper will not go below 30% to keep some fresh air coming into the building.
10 DAMPER = MIN( 90 , MAX( 30 , PID1 ) )
In this example the damper would be clipped to operate between 30% min and 90% max.