Issue
The Xenta 102-AX can be set to NIGHT_PURGE mode using the plug-in or VAV_Controller.nviApplicMode. The documentation does not state what this mode does.
Environment
Xenta 102-AX
Cause
The Xenta 102-AX Product Manual enumerates all of the possible modes for the controller, but does not go into detail about night purge or any of the other modes.
Resolution
NIGHT_PURGE mode will:
- Set the unit mode (nvoUnitStatus.MODE) to HVAC_NIGHT_PURGE
- Set the airflow setpoint (nvoFlowControlPt) to Cooling Maximum (SCPTmaxFlow)
The Xenta 102-AX will enter NIGHT_PURGE mode automatically when the unit is UNOCCUPIED and the terminal load is 100%.
NIGHT_PURGE mode will end and return to the active nviApplicMode when the terminal load reaches 0% or below.
Note: Heating outputs are not disabled in this mode. If the Xenta 102-AX is in night purge mode when it goes occupied it will be stuck in that mode. The box will not come out of night purge until the terminal load reaches 0% just as when it is unoccupied
