Trane LO manual Tracer ZN.520, Occupied Bypass Mode, Occupancy Sources

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.

Occupied Bypass 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).

Occupancy Sources

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,

UNT-IOM-6 63