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If the 50HCQ unit has an economizer system and
free--cooling operation is required, a sensor representing
Return Air Temperature must also be connected
(field--supplied and installed). This sensor may be a T--55
Space Sensor (see Fig. 31) installed in the space or in the
return duct, or it may be sensor PNO 33ZCSENSAT,
installed in the return duct. Connect this sensor to TB1--1
and TB1--3 per Fig. 32.
Configure the Unit for Thermostat Mode —
Connect to the CCN bus using a CCN service tool and
navigate to PremierLink Configuration screen for
Operating Mode. Default setting is Sensor Mode (value
1). Change the value to 0 to reconfigure the controller for
Thermostat Mode.
When the PremierLink is configured for Thermostat
Mode, these functions are not available: Fire Shutdown
(FSD), Remote Occupied (RMTOCC), Compressor Safety
(CMPSAFE), Supply Fan Status (SFS), and Filter Pressure
Switch (FILTER).
Economizer Controls
Outdoor Air Enthalpy Control
(PNO 33CSENTHSW) —
The enthalpy control (33CSENTHSW) is available as a
field--installed accessory to be used with the EconoMi$er2
damper system. The outdoor air enthalpy sensor is part of
the enthalpy control. (The separate field--installed
accessory return air enthalpy sensor (33CSENTSEN) is
required for differential enthalpy control. See Fig. 36.)
Locate the enthalpy control in the economizer next to the
Actuator Motor. Locate two GRA leads in the factory
harness and connect the gray lead labeled “ESL” to the
terminal labeled “LOW”. See Fig. 36. Connect the
enthalpy control power input terminals to economizer
actuator power leads RED (connect to 24V) and BLK
(connect to GND).
7
ESL
CTB
ECON
LOW
GND
24V
Enthalpy
Switch
GRA
BLK
RED
Factory Wiring Harness
ECONO
MOTOR
C09026
Fig. 36 -- Enthalpy Switch (33CSENTHSW) Connections
The outdoor enthalpy changeover setpoint is set at the
enthalpy controller.
Differential Enthalpy Control —
Differential enthalpy control is provided by sensing and
comparing the outside air and return air enthalpy
conditions. Install the outdoor air enthalpy control as
described above. Add and install a return air enthalpy
sensor.
Return Air Enthalpy Sensor —
Mount the return--air enthalpy sensor (33CSENTSEN) in
the return--air section of the economizer. The return air
sensor is wired to the enthalpy controller
(33CSENTHSW). See Fig. 37.
ESL
LOW
GND
24V
GRA
BLK
RED
ECONO
MOTOR
– 4-20
Main
+ VDC
Out
– 4-20 Main
Out
+ 24-36
VDC In
C09027
Fig. 37 -- Outside and Return Air Enthalpy Sensor
Wiring
To wire the return air enthalpy sensor, perform the
following:
1. Use a 2--conductor, 18 or 20 AWG, twisted pair cable
to connect the return air enthalpy sensor to the enthal-
py controller.
2. Connect the field--supplied RED wire to (+) spade
connector on the return air enthalpy sensor and the
(+) terminal on the enthalpy controller. Connect the
BLK wire to (--) spade connector on the return air en-
thalpy sensor and the (--) terminal on the enthalpy
controller.
Indoor Air Quality (CO
2
sensor) —
The indoor air quality sensor accessory monitors space
carbon dioxide (CO
2
) levels. This information is used to
monitor IAQ levels. Several types of sensors are available,
for wall mounting in the space or in return duct, with and
without LCD display, and in combination with space
temperature sensors. Sensors use infrared technology to
measure the levels of CO
2
present in the space air.
The CO
2
sensors are all factory set for a range of 0 to
2000 ppm and a linear mA output of 4 to 20. Refer to the
instructions supplied with the CO
2
sensor for electrical
requirements and terminal locations. See Fig. 38 for
typical CO
2
sensor wiring schematic.
50HCQA