©2020 Trane VAV-SVX07F-EN
Introduction
The Tracer® UC400 controller is a programmable, general-purpose BACnet®, microprocessor-
based, direct digital controller (DDC). This controller can be installed as a factory or field device.
When this controller is factory installed on Trane™ variable-air-volume (VAV) terminal units, the
factory downloads the unit with the appropriate VAV programs and configuration settings for the
unit. These can include sales-order-specified airflow setpoints.
Trane VAV units are made with either pneuma
tic or m
icroprocessor controls (DDC/VAV). This
manual considers only terminal units with BACnet UC400 controller DDC/VAV controls. Factory-
installed DDC/VAV controls are available with all single duct terminal units, parallel fan-powered,
and series fan-powered units.
The UC400 controller can be configured with thre
e (3) differ
ent application programs:
Space Temperature Control (STC)
When the UC400 controller is configu
red f
or STC, it modulates the VAV damper blade based on the
zone temperature, measured airflow, airflow and temperature, and setpoints, to continuously
control conditioned air delivery to the space. The volume of monitored incoming air and the
damper adjusts to provide accurate airflow control independent of the duct pressure. The damper
modulates discharge airflow into the space between operator airflow setpoints depending on
space conditions. Additionally, the fan and heat outputs may be energized depending on the
application.
Ventilation Flow Control (VFC)
When the UC400 controller is configured for VFC, it can be applied to a VAV terminal and used to
temp
er cold ou
tdoor air that is brought into a building for ventilation purposes. The tempered air
is intended to supply an air handler unit (AHU), which provides comfort control to the zones it is
serving. The VAV terminal supplies the correct amount of ventilation air. When reheat is added, it
tempers the ventilation air to reduce the load on the air handler by sensing the discharge air
temperature of the VAV unit, and controls its long-term average to the discharge air temperature
setpoint.
Communicated Discharge Air Temperature Setpoint range is
between 19°F and 70°F.
Flow Tracking Control (FTC)
When the UC400 controller is configured for FTC,
it wo
rks in conjunction with another UC400
configured for STC. The current discharge airflow from the STC controller is communicated to the
FTC controller. The FTC controller is then configured to supply a offset (positive or negative) flow
relative to the of the other VAV box(es). This is used to provide positive or negative pressure to a
contain zone. Warnings, Cautions, and Notices
Safety advisories appear throughout this manual as requ
ired. Your personal safety and the proper
operation of this machine depend upon the strict observance of these precautions.
Warnings, Cautions, and Notices
Safety advisories appear throughout this manual as required. Your personal safety and the proper
operation of this machine depend upon the strict observance of these precautions.
The three types of advisories are defined as follows:
WARNING
Indicates a potentially hazardous situation which, if not avoided, could result in
death or serious injury.
CAUTIONs
Indicates a potentially hazardous situation which, if no
t avoided, could result in
minor or moderate injury. It could also be used to alert against unsafe practices.
NOTICE
Indicates a situation that could result in equipment or property-damage only
accidents.
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