Trane LO - Manual (Page 92)

Terminal Unit
Control (TUC)
92 UNT-IOM-6
· Occupied
· Unoccupied
· Tracer ® with supply fan control
Occupied
In the occupied mode, the factory configures the TUC for continuous
occupied fan cycle. With the fan control set to auto, the fan operates
at the required speed to meet the cooling or heating capacity.
However, the fan will run at one set speed continuously if set in the
high, medium, or low position.
Unoccupied
In the unoccupied mode, the TUC cycles the fan between off and high
speed to satisfy the unoccupied setpoint. However, if the occupied
preheat damper position is closed and the room setpoint is 3° F
above (cool down) or 3° F below (warm-up) setpoint, the fan runs at
high speed when exiting the unoccupied mode to occupied mode.
Also, if the occupied preheat damper position is configured as
closed, the fan will run in high speed any time the room temperature
falls 3° F or below room setpoint in occupied heating mode.
Tracer ® with supply fan control
If the unit is communicating with Tracer ® and the supply fan control
programming point is configured for Tracer ® (the factory configures as
local), then Tracer ® will control the fan regardless of the fan mode
switch position.
All TUC lockouts (latching diagnostics) are manually reset whenever
the fan mode switch is set to the off position or when power is
restored to the unit. The last diagnostic to occur is retained until the
unit power is disconnected. Refer to Trane publication, EMTX-IOP-1
TUC Installation Operation and Programming Guide, for specific
instructions regarding the procedure for running the TUC.
Adjust the cooling setpoint by using either the setpoint adjustment
knob, resetting the TUC default values, or Tracer ® downloaded values.
The factory configures the occupied heat or cool setpoint source for
local mode. The local mode allows the local setpoint knob to deter-
mine the cooling setpoint If using Tracer ® to define the heat or cool
setpoint source, the TUC uses the Tracer ® setpoints. If Tracer ® is not
communicating, the TUC will attempt to obtain the heating and
cooling setpoint from a local source. If there is no input from a local
source, the TUC will resort to its default values.
The TUC limits the parameters of the cooling setpoint input (adjust-
able from either the setpoint knob or Tracer ® ) to prevent excessively
TUC Sequence of Operation
Cooling and
Heating Operation
Setpoint Control