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Connect T- - 59: The T- - 59 space sensor requires a
separate, isolated power supply of 24 VAC. See Fig. 45
for internal connections at the T- - 59. Connect the SEN
terminal (BLU) to RTU Open J20- - 1. Connect the COM
terminal (BRN) to J20- - 2. Connect the SET terminal (STO
or BLK) to J20- - 3.
BLK (STO)
BRN (COM)
BLU (SPT)
OR
SET
SEN
OPB
COM- PWR+
NOTE: Must use a separate isolated transformer.
Fig. 45 - - Space Temperature Sensor Typical Wiring
(33ZCT59SPT)
Indoor Air Quality (CO
) Sensor —
2
The indoor air quality sensor accessory monitors space
carbon dioxide (CO
) levels. This information is used to
2
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
present in the space air.
2
The CO
sensors are all factory set for a range of 0 to
2
2000 ppm and a linear mA output of 4 to 20. Refer to the
instructions supplied with the CO
requirements and terminal locations. See Fig. 46 for
typical CO
sensor wiring schematic.
2
To accurately monitor the quality of the air in the
conditioned air space, locate the sensor near a return- - air
grille (if present) so it senses the concentration of CO
leaving the space. The sensor should be mounted in a
location to avoid direct breath contact.
Do not mount the IAQ sensor in drafty areas such as near
supply ducts, open windows, fans, or over heat sources.
Allow at least 3 ft (0.9 m) between the sensor and any
corner. Avoid mounting the sensor where it is influenced
by the supply air; the sensor gives inaccurate readings if
the supply air is blown directly onto the sensor or if the
supply air does not have a chance to mix with the room air
before it is drawn into the return airstream.
J20-3
SENSOR
J20-2
WIRING
J20-1
POWER
WIRING
24 VAC
C10291
sensor for electrical
2
H G 24 VAC
OR
+ -
24 VDC
2 1
J3
Fig. 46 - - Indoor/Outdoor Air Quality (CO
(33ZCSENCO2) - - Typical Wiring Diagram
Wiring the Indoor Air Quality Sensor: For each sensor,
use two 2- - conductor 18 AWG (American Wire Gage)
twisted- - pair cables (unshielded) to connect the separate
isolated 24 vac power source to the sensor and to connect
the sensor to the control board terminals.
To connect the sensor to the control, identify the positive
(4 to 20 mA) and ground (SIG COM) terminals on the
sensor. See Fig. 46. Connect the 4- - 20 mA terminal to
RTU Open terminal J4- - 2 and connect the SIG COM
terminal to RTU Open terminal J4- - 3. See Fig. 47.
IAQ Sensor
24 VAC
Fig. 47 - - RTU Open / Indoor CO
(33ZCSENCO2) Connections
2
Outdoor Air Quality Sensor
(PNO 33ZCSENCO2 plus weatherproof enclosure) —
The outdoor air CO
2
dioxide (CO
) levels in the outside ventilation air and
2
interface with the ventilation damper in an HVAC system.
The OAQ sensor is packaged with an outdoor cover. See
Fig. 48. The outdoor air CO
economizer outside air hood.
33
+
0-10VDC
-
SIG COM
+
4-20mA
NC
}
ALARM
COM
RELAY
NO
CONTACTS
8 7 6 5 4 3 2 1
J4
) Sensor
2
4-20mA
SIG COM
Sensor
2
sensor is designed to monitor carbon
sensor must be located in the
2
C08635
J4-2
J4-3
C10738
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