The hydraulic grade (maximum) in my conduit is not equal to or close to the maximum hydraulic grade at the upstream manhole. Why?
The hydraulic grade(maximum) property of a conduit is the maximum hydraulic grade at middle of the conduit not at the beginning. If you are looking of the maximum hydraulic grade at the start of the conduit please move the time browser to a time when the hydraulic grade is at a maximum for the manhole and then refer to the "Hydraulic Grade Line (In)" property of the downstream conduit. This should be relatively equivalent to the maximum HGL in the manhole.