Terminal Unit
Control (TUC)
TUC Sequence of Operation
Cooling and Heating Operation
Setpoint Control
·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
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,
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
92 |
