38
BCXC-SVX01A-EN
Operation
Sequence of
Operation
Tracer Dehumidification (Tracer
ZN520 Only)
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% and uses the reheat capacity to
warm the discharge air to maintain space
temperature control. Dehumidification
may be disabled via Tracer or configura-
tion.
Note: If the unit is in the unoccupied
mode, the dehumidification routine will
not operate.
Table O-SO-9. Relationship Between Outdoor Temperature Sensors and Economizer
Damper Position (Tracer ZN520 Only)
Modulating Fresh Air Damper
Outdoor Air Temperature
Occupied or Occupied Bypass
Ocupied Standby
Unoccupied
None or invalid
Open to occupied
Open to occupied
Closed
minimum position
standby min. pos.
Failed
Open to occ.
Open to occ.
Closed
min.pos.
standby
min. pos.
Present and economizer
Economizing:
Economizing:
Open and econ.
feasible
min pos. to 100%
between occ.
only when unit
standby min.
operating,
pos. to 100%
closed
otherwise
Present and economizer
Open to occ.
Open to occ.
Closed
not feasible
min. pos.
standby min pos.
Data Sharing (Tracer ZN510 or
ZN520 Only)
Because this controller utilizes
LonWorks™ technology, the 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 the Trane publication
EMTX-IOP-2.
