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Dehumidification Operation
The controller supports space dehumidification when:
•
Mechanical (DX or hydronic) cooling is available
•
The heating capacity is located in the reheat position
•
The space relative humidity is valid
The space relative humidity can 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
Peer-to-peer communication is accomplished by means of
custom TGP2 programming in the Tracer
controller or via hard wiring only between controllers.
Unit Protection Strategies
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
The 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
For more information, refer to Tracer® UC400-B
Programmable Controller for Blower Coil, Fan Coil, and
Unit Ventilator Installation, Operation, and Programming
Guide (BAS-SVX48*EN ) and the preceding section
Reset," p.
112.
112
®
SC system
"Smart
Condensate Overflow
For more information, refer to Tracer
Programmable Controller for Blower Coil, Fan Coil, and
Unit Ventilator Installation, Operation, and Programming
Guide (BAS-SVX48*EN ).
Fan Status
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. 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 controller energizes 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 the
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 VelociTach 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
After heating has been controlled OFF, the controller keeps
the fan energized for an additional 30 seconds in order to
remove residual heat from the heating source.
Filter Maintenance Timer
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
The 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 begins
®
UC400-B
®
TU.
BCX-SVX002A-EN
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Table of Contents
Troubleshooting
