Trane LO - Manual (Page 98)

Terminal Unit
Control (TUC)
98 UNT-IOM-6
BIP4: Smoke Input
BIP3: Occupied/
Unoccupied Mode
BIP1: External
Interlock
and the electric heat to disable. This creates an immediate shutdown
latching diagnostic, which requires a manual or Tracer â reset to
resume normal operation.
However, normal operation cannot resume until the water level
recedes to an acceptable level. The switch will close after the water
level recedes, and the active temperature control of the unit will
resume by an automatic reset. Since both the condensate overflow
detection and occupied/unoccupied status occupy BIP3 on the TUC
board, only one option can be in use. The factory configures the 24V
dry contact input as normally closed to indicate an alarm. However, it
also can be normally open if using the correct switch.
The smoke input is a binary input on the TUC that is used with a
smoke detector switch (installer supplied) to signal an alarm. Config-
ure the input to either send an alarm to Tracer ® or as a shutdown
latching diagnostic. If the input is configured as a shutdown latching
diagnostic, the TUC closes the control valve(s), shuts the fan off,
closes the fresh air damper, and disables electric heat.
If the input is configured to send an alarm, Tracer will issue a system
wide shutdown for the building. The unit will continue to run, and no
diagnostic will register within the TUC. The factory configures the
24V dry contact input as normally closed. However, it can also be
normally open if using the correct switch.
The unit can operate in the occupied/unoccupied mode when a
binary signal is input from an external source such as a time clock or
Tracer ® . Reference the “TUC Fan Mode Operation” section on page
65 for the sequence of operations. This option is only available if the
condensate overflow input is not in use (if not using Tracer ® ), since
both inputs occupy the same point on the TUC board. The factory
configures the 24V dry contact input as normally closed. However, it
can also be normally open if using the correct switch. A closed
signal indicates occupied mode.
The external interlock input allows the unit to be remotely stopped
when a binary signal is input to the TUC from an external source or
from Tracer ® . Since both external interlock and condensate overflow
input to the same point (if not using Tracer ® ) on the TUC board, only
one input can be in use. The factory configures the 24V dry contact
input as normally closed, but it can also be open if using the correct
switch.