Control of AirTerminal:SingleDuct:VAV:Reheat

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General Advice for Sizing Problems with VAV Systems

1. Make sure Zone Heating Design Supply Air Temperature in Sizing:Zone matches the Maximum Reheat Air Temperature in the AirTerminal:SingleDuct:VAV:Reheat assigned to this zone. If the sizing temperature is higher than the maximum reheat temperature, then during operation the terminal isn't allowed to operate at the temperature it was designed for, meaning that it can't provide the designed heating capacity.
2. Make sure that the Design Loop Exit Temperature in the Sizing:Plant for the Hot Water PlantLoop matches the Winter Design Day Schedule in the SetpointManager:Scheduled assigned to your Hot Water PlantLoop. If everything is sized for high temperature water but then operated at a lower temperature, sometimes the equipment can't meet the load.
3. Make sure that the Rated Inlet Water Temperature and Rated Outlet Water Temperature of theCoil:Heating:Water Reheat Coils match the Design Loop Exit Temperature and Loop Design Temperature Difference in theSizing:Plant for the Hot Water PlantLoop. This ensures that the coils and their plant loop are sized with the same temperature and delta-T.

So for your particular IDF:

1. Change Zone Heating Design Supply Air Temperature from 40C to 35C to match max reheat
2. Change Design Loop Exit Temperature for Hot Water Loop from 82.2C to 67C to match HW setpoint
3. Change Rated Inlet Water Temperature for Reheat Coils from 82.2C to 67C to match HW setpoint
4. Change Rated Outlet Water Temperature for Reheat Coils from 71.1C to 55.9C to match HW delta-T

Result: Time Setpoint Not Met During Occupied Heating drops from 1145.00 to 234.33