Occupied Bypass Mode; Timed Override Control; Heat/Cool Operation - Trane Tracer UC400 Installation, Operation And Maintenance Manual

Occupied Bypass Mode

The UC400 Controller is placed in occupied bypass mode when:
•
•
In occupied bypass mode, the controller maintains the space temperature based on the occupied
heating or cooling setpoints. The fan runs as configured (continuous or cycling). The outdoor air
damper closes when the fan is OFF. The controller remains in occupied bypass mode until either
the CANCEL button is pressed on the Trane zone sensor or the occupied bypass time expires
(configured using the Tracer TU service tool). The temperature setpoints can be configured as
local (hard wired), communicated, or stored default values using the Tracer TU service tool.

Timed Override Control

If the zone sensor has a timed override option (ON/CANCEL buttons), pushing the ON button
initiates a timed override on request. A timed override upon request changes the occupancy
mode from unoccupied mode to occupied bypass mode. In occupied bypass mode, the controller
controls the space temperature based on the occupied heating or cooling setpoints. The
occupied bypass time, which defines the duration of the override and resides in the controller, is
configured from 0 to 240 minutes (default value of 120 minutes). When the occupied bypass time
expires, the controller transitions from occupied bypass mode to unoccupied mode.
Pushing the CANCEL button cancels the timed override request. In addition, it ends the timed
override before the occupied bypass time has expired and transitions the unit from occupied
bypass mode to unoccupied mode. If the controller is in any mode other than unoccupied mode
when the ON button is pressed, it still starts the occupied bypass timer without changing to
occupied bypass mode. If the controller is placed in unoccupied mode before the occupied
bypass timer expires, it is placed into occupied bypass mode and remains in this mode until
either the CANCEL button is pressed on the Trane zone sensor or the occupied bypass time
expires.

Heat/Cool Operation

Cooling
During the cooling mode, the UC400 Controller uses one of the following cooling modes to
maintain the space temperature at the active cooling setpoint:
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•
•
The UC400 Controller uses the measured space temperature and the active cooling setpoint
along with the control algorithm, to determine the requested cooling capacity of the unit (0-
100%). The outputs are controlled based on the unit configuration and the requested cooling
capacity.
N N o o t t e e : : If humidity control is enabled, refer
Heating
During the heating mode, the UC400 Controller uses one of the following heating modes to
maintain the space temperature at the active heating setpoint:
•
•
•
The UC400 Controller uses the measured space temperature and the active heating setpoint,
along with the control algorithm, to determine the requested heating capacity of the unit (0-
100%). The outputs are controlled based on the unit configuration and the requested heating
capacity.
BAS-SVX065E-EN
The controller is operating in the unoccupied mode and the timed override ON button on the
Trane zone sensor is pressed (see Timed Override Control below).
The controller receives an occupied bypass signal from a BAS.
Occupied Cooling
Occupied Standby Cooling
Unoccupied Cooling
Occupied Heating
Occupied Standby Heating
Unoccupied Heating
"Other Modes," p. 43.
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