Trane VUV Installation, Operation And Maintenance Manual page 78

Start-Up
using a modulating damper during the occupied, occupied
standby, unoccupied, and occupied bypass modes.
The controller initiates the economizer function if the fresh air
temperature is cold enough for use as free cooling capacity. If
the fresh air temperature is less than the economizer enable
setpoint (absolute dry bulb), the controller modulates the fresh
air damper (between the active minimum damper position and
Table 27. Relationship between outdoor temperature sensors and economizer damper position (Tracer® ZN520 and
UC400-B/Symbio™ 400-B controllers only)
Outdoor Air Temperature
None or invalid
Failed
Present and economizer feasible
Present and economizer
not feasible
Dehumidification
Dehumidification is possible when mechanical cooling is
available, the heating capacity is located in the reheat position,
and the space relative humidity setpoint is valid.The controller
starts dehumidifying the space when the space humidity
exceeds the humidity setpoint.
The controller continues to dehumidify until the sensed
humidity falls below the setpoint minus the relative humidity
offset.The controller uses the cooling and reheat capacities
simultaneously to dehumidify the space. While dehumidifying,
the discharge air temperature is controlled to maintain the
space temperature at the current setpoint.
A typical scenario involves high humidity and high temperature
load of the space.The controller sets the cooling capacity to
100 percent and uses the reheat capacity to warm the
discharge air to maintain space temperature control.
Dehumidification may be disabled via Tracer® or
configuration.
Note: If the unit is in the unoccupied mode, the
dehumidification routine will not operate.
Data Sharing
Because this controller utilizes L
controller can send or receive data (setpoint, heat/cool mode,
fan request, space temperature, etc.) to and from other
controllers on the communication link, with or without the
existence of a building automation system. This applies to
applications where multiple unit
controllers share a single space temperature sensor (for
rooms with multiple units but only one zone sensor) for both
standalone (with communication wiring between units) and
building automation system applications. For this application
you will need to use the Rover service tool.
For more information on setup, refer to:
• EMTX-SVX01*-EN Rover Service Tool Installation,
Operation, and Programming manual.
78
Modulating Fresh Air Damper
Occupied or Occupied Bypass
Open to occupied minimum position
Open to occupied minimum position
Economizing: minimum position
to 100%
Open to occupied minimum position
®
W technology, the
ON ORKS
100 percent) to control the amount of fresh air cooling capacity.
When the fresh air temperature rises 5°F above the
economizer enable point, the controller disables economizing
and moves the fresh air damper back to its predetermined
minimum position based on the current occupancy mode or
communicated minimum damper position.
Occupied Standby
Open to occupied standby
minimum position
Open to occupied standby
Economizing: between occupied standby
minimum position to 100%
Open to occupied standby minimum position
Binary Inputs
Tracer® ZN520 controller has four available binary inputs.
Normally, these inputs are factory-configured for the following
functions:
• Binary input 1: Low temperature detection (freezestat)
• Binary input 2: Condensate overflow
• Binary input 3: Occupancy/ Generic
• Binary input 4: Fan status
Note: The generic binary input can be used with a Tracer
Summit® building automation system only.
Each binary input default configuration (including normally
open/closed) is set at the factory. However, you can configure
each of the four binary inputs as normally open or normally
closed. The controller will be set properly for each factory-
supplied binary input end-device. When no device is
connected to the input, configure the controller's input as not
used.
Unoccupied
Closed
Closed
Open and economizing only when unit
operating, closed otherwise
Closed
UV-SVX005G-EN