Sequence Of Operation; Power-Up Sequence; Random Start; Occupancy Modes - Trane Tracer UC400 Installation, Operation And Maintenance Manual

Sequence of Operation

The UC400 Controller operates to maintain the space temperature setpoint.

Power-up Sequence

1. The following sequence occurs when 24 Vac power is initially applied to the UC400
2. All outputs are controlled OFF and all modulating valves and dampers close.
3. The controller reads all input local values to determine initial values.
4. The random start timer begins.
5. The random start timer expires.
6. Normal operation begins, assuming there are no generated diagnostics. If any points are in

Random Start

Random start prevents all units in a building from energizing at the same time. The random start
timer delays the fan and any heating or cooling startup from 5 to 30 seconds.

Occupancy Modes

Occupancy modes can be controlled by the following methods:
•
•
•
A communicated request, from either a Tracer SC or BAS, takes precedence over local requests.
If a communicated occupancy request has been established, and is no longer present, the UC400
Controller reverts to the default (occupied) occupancy mode after 15 minutes (if no hard wired
occupancy request exists). The controller has the following occupancy modes:
•
•
•
•

Occupied Mode

In Occupied Mode, the UC400 Controller maintains the space temperature based on the occupied
space temperature setpoint ± occupied offset. When occupied, the fan can be configured to
operate continuously (default) or cycle ON/OFF with demand, based on BV/1 (Supply Fan
Configuration Command). The controller uses the occupied mode as a default mode when other
forms of occupancy requests are not present. The outdoor air damper, if present, closes when
the fan is OFF. The temperature setpoints can be local (hard wired), communicated, or stored
default values (configured using the Tracer TU service tool).
BAS-SVX48H-EN
Controller:
• The Power Marquee LED turns on as red, then
• Flashes green, and then
• Stays lit as constant green.
fault or alarm mode, the Power Marquee LED flashes red.
I I m m p p o o r r t t a a n n t t : : Flashing red does not indicate that the UC400 Controller fails to operate. Instead,
the point(s) that are in fault or alarm mode should be checked to determine if the
status of the point(s) is acceptable to allow equipment operation.
The state of the local (hard wired) occupancy binary input BI1.
A timed override request from a Trane zone sensor.
A communicated signal from either a Tracer SC or BAS.
Occupied
Unoccupied
Occupied Standby
Occupied Bypass
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