LX Series Unit Ventilator Controller User's Guide34
• A schedule change by a supervisory node sets the network variable
nviOccCmd to OC_UNOCCUPIED. Because nviOccManCmd has priority
over nviOccCmd, nviOccManCmd must be set to OC_NUL for the schedule
change to occur.
• The occupancy contact is open or not assigned and both nviOccManCmd and
nviOccCmd are set to OC_NUL. This method can be used to manually switch
between occupied and unoccupied modes.
• The window contact is opened.
During the unoccupied state, the controller heats or cools the space as required to
maintain the temperature within the limits described by the unoccupied setpoints.
The fresh air damper is closed unless a cooling demand exists and the damper is
enabled.
Note: In unoccupied mode, the setpoint offset from input or network variable has
no effect on the effective setpoint.
Ending Unoccupied Mode
Unoccupied mode ends when any one of the following occurs:
• Another mode is commanded by nviOccCmd while nviOccManCmd is set to
OC_NUL. This method can be used to implement a schedule.
• Another mode is commanded by nviOccManCmd. This method can be used as
a manual override.
• The bypass button on the space temperature sensor is pressed. This button
short-circuits the sensor.
• The occupied contact is closed and both nviOccCmd and nviOccManCmd are
invalid.
• The bypass contact input is pressed.
• The window contact is closed. The Unit Ventilator Controller enters the
currently scheduled mode or the mode currently commanded by the occupancy
contact.
Bypass Mode
Bypass mode uses the occupied setpoints to provide a comfortable environment
when individuals are using a space outside of the normal scheduled time.
Bypass mode is temporary. The duration of bypass mode is a time period called
bypass time. Bypass time is set on the General Settings configuration screen.
When the Unit Ventilator Controller enters bypass mode, the bypass time period
begins; when the bypass time period ends, the Unit Ventilator Controller exits
bypass mode.
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