A bug report.
I ran an ExampleFile 5ZoneAirCooledWithDOASAirLoop_ExhaustSystem.idf to see how AirLoopHVAC:ExhaustSystem works. The central exhaust fans in the idf file do not operate.
I identified the cause. Minimum Exhaust Flow Fraction Schedule Name in ZoneHVAC:ExhaustControl is left blank.
I/O Reference says "If left empty, the default value would be 1.0", but I doubt it. If this field is left blank, the default value seems to be 0.
For now, enter a schedule including 1 (usually the same as the fan availability shcedule) in Minimum Exhaust Flow Fraction Schedule Name and the associated exhaust fan will operate.
