Trane Tracer UC400 User Manual

BAS-SVX48H-EN
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Valve Operation
The UC400 Controller supports 1–, 2–modulating or 2-position valves, depending on the
application. The controller opens and closes the appropriate valve(s) to maintain the active zone
temperature setpoint at the heating setpoint in heating mode or the cooling setpoint in cooling
mode.
Modulating Valve Operation
The UC400 Controller supports 3-wire floating point and analog modulating valve control. Two
(2) binary outputs control each valve: one to drive the valve open and one to drive the valve
closed. The stroke time for each valve is configured using the Tracer TU service tool. The
controller supports the following:
• Heating.
• Cooling.
• Heat/cool changeover with a single valve and coil for 2-pipe applications.
• Cooling or heat, cool changeover with the main valve, and coil.
• Only heating with the auxiliary valve and coil for 4-pipe applications.
The UC400 moves the modulating valve to the desired positions based on heating or cooling
requirements.
3–Wire Floating Point Valve Calibration
The 3-wire floating point valve calibration is automatic. During normal operation, the UC400
Controller overdrives the actuator (135% of the stroke time) whenever there is a request for a
position of 0% or 100%. At either power-up, after a power outage, or when the occupancy status
changes to unoccupied, the controller first drives all modulating valves (and dampers) to the
closed position. The controller calibrates to the fully CLOSED position by over driving the
actuator (135% of the stroke time) and then resumes normal operation.
2–Position Valve Operation
The UC400 Controller supports 2-position valves with a single binary output for each valve.
Controllers used for 2-pipe applications support heating, cooling, or heat/cool changeover with a
single valve/coil. A controller used for 4-pipe applications supports cooling or heat/cool
changeover with a main valve/coil and heating only with an auxiliary valve/coil.
Face/Bypass Damper Operation
When configured for use, the face and bypass damper actuates to modulate a percentage of air
to the face of the coil and around the coil (bypass) in order to maintain space comfort. Isolation
valves are used to control water flow through the unit during heating and cooling operation.
Modulating Outdoor/Return Air Damper
The UC400 Controller operates the modulating outdoor/return air dampers based on the
following:
• Occupancy mode.
• Outdoor air temperature (communicated or hard wired sensor).
• Zone temperature.
• Setpoint.
• Discharge air temperature.
• Discharge air temperature setpoint.
The minimum position for an outdoor air damper is configured using the Tracer TU service tool
for both occupied mode and occupied standby mode and for low-speed fan operation. The
UC400 Controller can receive a BAS-communicated outdoor air damper minimum position. A
BAS-communicated minimum position setpoint has priority over all locally configured setpoints.
When a communicated minimum position setpoint is not present, the controller uses the
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Trane Tracer UC400 Specifications

General

Brand	Trane
Model	Tracer UC400
Category	Controller
Language	English