Face and Bypass Switchover options are available if you have selected a face and bypass coil. As the switchover temperature falls below the switchover setpoint, the application changes from modulating the valve to modulating the damper. You may switch your face and bypass damper control Based on Outdoor Air Temperature, Based on Mixed Air Temperature, or Based on Network Input.
The Face and Bypass Switchover option is applicable only when either a Proportional or Incremental valve actuator is selected with Face and Bypass Damper. This option specifies how to determine when the valve should be in control (with the Damper at full face) and when the damper should be in control (with the Valve fully open).