BCXC-SVX01A-EN
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Operation
Sequence of
Operation
Zone Sensor
The Tracer
ZN controller accepts the
following zone sensor module inputs:
• Space temperature measurement
(10kW thermistor)
• Local setpoint (either internal or
external on the zone sensor module)
• Fan mode switch
• Timed override , using “on” and
“cancel” buttons (Tracer ZN510 and
ZN520 only)
• Communication jack (Tracer ZN510 and
ZN520 only)
Space Temperature Measurement
Zone sensors use a 10kW thermistor to
measure the space temperature. Wall-
mounted zone sensors include a space
temperature thermistor. Unit-mounted
zone sensors have a return air sensor
mounted in the unit’s return airstream. If
both a hardwired and communicated
space temperature value exists, the
controller ignores the hardwired space
temperature input and uses the
communicated value.
Local Setpoint
The zone sensor may be equipped with a
thumbwheel for setpoint adjustment.
Fan Mode Switch
The zone sensor may be equipped with a
fan mode switch. The fan mode switch
offers selections of off, low, high, or auto.
External Setpoint Adjustment
Zone sensors with an external setpoint
adjustment (1kW) provide the Tracer ZN
controller with a local setpoint (50 to 85°F
or 10 to 29.4°C). The external setpoint is
exposed on the zone sensor’s front cover.
When the hardwired setpoint adjustment
is used to determine the setpoints, all unit
setpoints are calculated based on the
hardwired setpoint value, the configured
setpoints, and the active mode of the
controller. The hardwired setpoint is used
with the controller’s occupancy mode
(occupied, occupied standby, or unoccu-
pied), the heating or cooling mode, the
temperature deadband values, and the
heating and cooling setpoints (high and
low limits) to determine the controller’s
active setpoint.
When a building automation system or
other controller communicates a setpoint
to the controller, the controller ignores the
hardwired setpoint input and uses the
communicated value. The exception is
the unoccupied mode, when the control-
ler always uses the stored default
unoccupied setpoints. After the controller
completes all setpoint calculations, based
on the requested setpoint, the occupancy
mode, the heating and cooling mode, and
other factors, the calculated setpoint is
validated against the following setpoint
limits:
• Heating setpoint high limit
• Heating setpoint low limit
• Cooling setpoint high limit
• Cooling setpoint low limit
Note: Only units with ZN510 or ZN520
can receive a communicated setpoint
from Tracer or other building automation
system. However, Rover service
software can communicate with all
Tracer ZN controllers.
These setpoint limits only apply to the
occupied and occupied standby heating
and cooling setpoints. These setpoint
limits do not apply to the unoccupied
heating and cooling setpoints stored in
the controller’s configuration.
When the controller is in unoccupied
mode, it always uses the stored unoccu-
pied heating and cooling setpoints.The
unit can also be configured to enable or
disable the local (hardwired) setpoint.
This parameter provides additional
flexibility to allow you to apply communi-
cated, hardwired, or default setpoints
without making physical changes to the
unit.
Similar to hardwired setpoints, the
effective setpoint value for a communi-
cated setpoint is determined based on
the stored default setpoints (which
determines the occupied and occupied
standby temperature deadbands) and
the controller’s occupancy mode.
Fan Switch
The zone sensor fan switch provides the
controller with an occupied (and occupied
standby) fan request signal (Off, Low,
High, Auto). If the fan control request is
communicated to the controller, the
controller ignores the hardwired fan
switch input and uses the communicated
value. The zone sensor fan switch input
can be enabled or disabled through
configuration using the Rover service
tool. If the zone sensor switch is disabled,
the controller resorts to its stored
configuration default fan speeds for
heating and cooling, unless the controller
receives a communicated fan input.
When the fan switch is in the off position,
the controller does not control any unit
capacity. The unit remains powered and
all outputs drive to the closed
position.Upon a loss of signal on the fan
speed input, the controller reports a
diagnostic and reverts to using the
default fan speed.
On/Cancel Buttons
Momentarily pressing the on button
during unoccupied mode places the
controller in occupied bypass mode for
120 minutes. You can adjust the number
of minutes in the unit controller
configuration using Rover service tool.
The controller remains in occupied
bypass mode until the override time
expires or until you press the Cancel
button.
Communication Jack
Use the RJ-11 communication as the
connection point from Rover™ service
tool to the communication link—when the
communication jack is wired to the
communication link at the controller. By
accessing the communication jack via
Rover™, you gain access to any
controller on the link.
Table O-SO-13. Zone Sensor Wiring
Connections
TB1
Description
1
Space temperature
2
Common
3
Setpoint
4
Fan mode
5
Communications
6
Communications
