Trane LO - Manual (Page 93)

UNT-IOM-6 93
Terminal Unit
Control (TUC)
high or low temperatures. In addition, the TUC calculates the heating
setpoint equal to the cooling setpoint minus an adjustable heating
offset. Furthermore, the heating setpoint cannot exceed a value less
than or equal to the cooling setpoint. The TUC is in the cooling mode
when the space temperature rises 1° F above the cooling setpoint.
The TUC is in the heating mode when the space temperature drops 1°
F below the heating setpoint. The unoccupied setpoints are typically
widened to account for night setback and are adjustable with either
Tracer ® or EveryWareä software.
Off Position
On a stand-alone TUC with the fan mode switch in the off position, all
normal cooling and heating functions cease. (e.g. The fan does not
run, the fresh air damper option closes, and the unoccupied mode
disables.)
High, Medium, or Low Postion
With the fan mode switch in the high, medium, or low position; the
fresh air damper option and the control valve(s) operate to maintain
setpoint.
Auto Position
As the capacity requirement increases at low fan speed, the control
valve gradually opens. The fan speed increases to medium after
reaching the low speed capacity switch point. This causes the control
valve to reposition to maintain capacity, gradually opening as demand
increases. The fan speed increases to high after reaching the medium
speed capacity switch point. This causes the control valve to reposi-
tion to maintain output capacity, gradually opening as demand
increases. As capacity decreases, the control valve closes until
reaching the fan switch point. After reaching the fan switch point, the
fan speed decreases to medium with the control valve repositioning to
maintain constant capacity. As capacity decreases, the control valve
closes until reaching the fan switch point. After reaching the fan
switch point, the fan speed decreases to low with the control valve
repositioning to maintain constant capacity. At low speed, the control
valve closes incrementally as demand decreases.
Fan Mode
Operation