VAV Air Terminal w/ Reheat - Zero flow when HVAC available
Hi all.
I have an E+ model of an office building with VAV AHUs with reheat at the zone level VAV boxes. AirTerminal:SingleDuct:VAV:Reheat with Zone Minimum Air Flow Input set at 0.30. HVAC Availability Schedule kicks on at 6am. Heating setpoint goes from 65 (before 7am) to 70F (at 7am).
However, at this point (6 to 7am) during each day in the heating season (most of my unmet hours are in heating mode), this damper goes to ZERO airflow and therefore zero heating energy to the space. Instead of the zone temperature rising to meet the now-increased setpoint, it falls for just one hour at 7am, and then increases up to setpoint. The space with the largest amount of unmet hours is "143 DOCK" so I have used this as my test space.
For troubleshooting, I have adjusted just about every setting and schedule that applies to this system - gradually raise setpoint rather than stepwise, shift hvac availability to 4am to ensure the system is "ready" for the onset of people/ventilation, gradually raise outdoor air fraction schedule to ensure the issue isn't because of an inrush of cold outdoor air, and even double checked to make sure the diffuser's Minimum Air Flow Fraction Schedule NEVER goes to zero.
Any explanation for this behavior? Thank you!
Files and annotated image showing the issue located here.
