Installation and Maintenance Manual

Startup
104 UNT-SVX07D-EN
• The heating capacity is located in the reheat position
• The space relative humidity is valid
The space relative humidity c
an be a BAS-communicated
value or come directly from a wired relative humidity
sensor. The controller begins to dehumidify the space
when the space humidity exceeds the humidity setpoint.
The controller continues to dehumidify until the sensed
humidity falls below the setpoint minus the relative
humidity offset.
Peer-to-peer Communication (UC400)
Peer-to-peer communication is accomplished by means of
custom TGP2 programming in the Tracer SC system
controller or via hard wiring only between controllers.
Unit Protection Strategies (UC400)
The following unit protection strategies are initiated when
specific conditions exist in order to protect the unit or
building from damage:
• Smart reset
• Low coil temperature protection
• Condensate overflow
•Fan status
• Fan off delay
• Filter maintenance timer
• Freeze avoidance
• Freeze protection (discharge air temperature low limit)
Smart Reset (UC400)
The UC400 controller will automatically restart a unit that
is locked out as a result of a Low Coil Temp Detection
(BI3) diagnostic. Referred to as smart reset, this automatic
restart will occur 30 minutes after the diagnostic occurs. If
the unit is successfully restarted, the diagnostic is cleared.
If the unit undergoes another Low Coil Temp Detection
diagnostic within a 24-hour period, the unit will be locked
out until it is manually reset.
Note: Freeze protection will also perform a smart reset.
Low Coil Temperature Protection (UC400)
For more information refer to Installation, Operation, and
Maintenance: Tracer™ UC400 Programmable Controller
Factory- or Field-installed for Blower Coil and Fan Coil
(BAS-SVX48B-EN, or the most recent revision) and the
preceding section, “Smart Reset (UC400)”.
Condensate Overflow (UC400)
For more information refer to Installation, Operation, and
Maintenance: Tracer™ UC400 Programmable Controller
Factory- or Field-installed for Blower Coil and Fan Coil
(BAS-SVX48B-EN, or the most recent revision).
Fan Status (UC400)
In 1-, 2- and 3-speed fans, the status is based on the
statuses of the supply fan output multistate and analog
points dedicated to fan control. The fan status is reported
as HIGH, MEDIUM, LOW, and as a percentage, whenever
the fan is running. The fan status is reported as OFF
whenever the fan is not running. In addition, a fan status
switch can be connected to binary input 5 (BI5) to monitor
the status of the fan for belt-driven or direct-driven units
(except Trane Macon factory ECM fan motor units). The fan
status switch provides feedback to the controller as
follows:
• If the fan is not operating when the
controller has the
fan controlled to ON, the controller generates a Low
Airflow-Supply Fan Failure diagnostic.
• If the UC400 controller energi
zes the fan output for
1 minute, and the fan status switch indicates no fan
operation, the controller performs a unit shutdown
and generates a Low Airflow-Supply Fan Failure
diagnostic.
• If the fan has been operating
normally for one minute,
but the fan status switch indicates no fan operation, the
same diagnostic is generated.
This manual diagnostic discontinues unit operation until
th
e diagnostic has been cleared from the controller. If a
diagnostic reset is sent to the controller, and the fan
condition still exists, the controller attempts to run the fan
for 1 minute before generating another diagnostic and
performing a unit shutdown. A diagnostic reset can be
sent to the controller from the Tracer TU Alarms page or by
temporarily overriding the Reset Diagnostic Request on
the Tracer TU Binary Status page.
Note: In the ECM fan application, the ECM engine board
will monitor the status of the fan. In case of a
failure, the engine board will disable the motor
immediately, and the low airflow diagnostic is sent.
Fan Off Delay (UC400)
After heating has been controlled OFF, the UC400
controller keeps the fan energized for an additional 30
seconds in order to remove residual heat from the heating
source.
Filter Maintenance Timer (UC400)
The filter maintenance timer tracks the amount of time (in
hours) that the fan is enabled. The Filter Runtime Hours
Setpoint (configurable using the Tracer TU service tool) is
used to set the amount of time until maintenance
(typically, a filter change) is required. The timer can be
enabled/disabled from the Supply Fan group on the
Setup Parameters page in Tracer TU.
The UC400 controller compares the fan run time to filter
runtime hours setpoint. Once the setpoint is reached, the
controller generates a Filter Change Required
diagnostic. When the diagnostic is cleared, the controller
resets the filter maintenance timer to zero, and the timer
UNT-SVX07_-EN.book Page 104 Friday, April 27, 2012 9:40 AM