Trane LO - Manual (Page 63)

UNT-IOM-6 63
Tracer ® ZN.520
standby cooling and heating setpoints. Because the occupied
standby setpoints typically cover a wider range than the occupied
setpoints, the Tracer ® ZN.520 controller reduces the demand for
heating and cooling the space. Also, the outdoor air economizer
damper uses the economizer standby minimum position to reduce
the heating and cooling demands.
When no occupancy request is communicated, the occupancy binary
input switches the controller’s operating mode between occupied and
unoccupied. When no communicated occupancy request exists, the
unit cannot switch to occupied standby mode.
The controller can be placed in occupied bypass mode by either
communicating an occupancy request of Bypass to the controller or
by using the timed override On button on the Trane zone sensor.
When the controller is in unoccupied mode, you can press the On
button on the zone sensor to place the controller into occupied
bypass mode for the duration of the bypass time (typically 120
minutes).
There are four ways to control the controller’s occupancy:
• Communicated request (usually provided by the building automation
system or peer device)
• By pressing the zone sensor’s timed override On button
• Occupancy binary input
• Default operation of the controller (occupied mode)
A communicated request from a building automation system or
another peer controller can change the controller’s occupancy.
However, if communication is lost, the controller reverts to the default
operating mode (occupied) after 15 minutes (configurable, specified
by the “receive heartbeat time”), if no local hardwired occupancy
signal exists.
A communicated request can be provided to control the occupancy of
the controller. Typically, the occupancy of the controller is determined
by using time-of-day scheduling of the building automation system.
The result of the time-of-day schedule can then be communicated to
the unit controller.
For complete information about the setup for Tracer Summit ® applica-
tions of this controller, see the Tracer Summit ® product literature. For
more information on the setup of another building automation system,
Occupied Bypass Mode
Occupancy Sources