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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 re-
turn airstream.
To controller
-
2 1
24 Vac
or Vdc
8 7 6 5 4
Fig. 76 — Indoor/Outdoor Air Quality (CO
(33ZCSPTCO2-01 or 33ZCSPTCO2LCD-01) 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 con-
trol 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. 76. Connect the 4-20 mA terminal to the RTU Open con-
troller at J4-2 and connect the SIG COM terminal to the RTU
Open controller at J4-3. See Fig. 77.
IAQ Sensor
SEN
COM
24 VAC
Fig. 77 — RTU Open Controller/Indoor CO
(33ZCSPTCO2-01 or 33ZCSPTCO2LCD-01)
Connections
OUTDOOR AIR QUALITY SENSOR (P/N 33ZCSPT-
CO2-01 OR 33ZCSPTCO2LCD-01 PLUS WEATHER-
PROOF ENCLOSURE) — The outdoor air CO
designed to monitor carbon dioxide (CO
24 Vac
Line
+
Dedicated Transformer
SENSOR LEGEND
1 +24 Vac/Vdc
2 Gnd (-24 Vac/Vdc)
4 -Thermistor
5 +Thermistor
6 4-20 mA
7 SIG COM
8 0-5 Vdc
) Sensor
2
J4-2
J4-3
Sensor
2
sensor is
2
) levels in the outside
2
ventilation air and interface with the ventilation damper in an
HVAC system.
The OAQ sensor is packaged with an outdoor cover. See
Fig. 76. The outdoor air CO
economizer outside air hood.
Wiring the Outdoor Air CO
supply is required for this sensor. A two-wire cable is required
to wire the dedicated power supply for the sensor. The two
wires should be connected to the power supply and terminals 1
and 2.
To connect the sensor to the control, identify the positive (4
to 20 mA) and ground (SIG COM) terminals on the OAQ sen-
sor. See Fig. 76. Connect the 4 to 20 mA terminal to the RTU
Open controller at J4
—
the RTU Open controller at J4
OAQ Sensor
24 VAC
Fig. 78 — RTU Open Controller/Outdoor CO
Sensor (33ZCSPTCO2-01 or 33ZCSPTCO2LCD-01)
SPACE RELATIVE HUMIDITY SENSOR OR HUMIDI-
STAT
Humidi-MiZer® System Control Wiring
equipped with the Humidi-MiZer option there are two loose
wires loose in the control box (one PNK and one PNK/BLK)
used to control the dehumidification function of the unit. These
wires are meant to be tied to a space humidistat or thermidistat
on an electromechanical unit. On RTU Open controller
equipped units these wires must be connected to J11
to allow the Open board to operate the dehumidification func-
tion for the unit. Disconnect the J11 Phoenix style connector
from the board and use the plug screws to secure the wires as
follows: secure the PNK/BLK wires at pin 7 and the PNK
wires at pin 8, and then reconnect the plug to the board at J11.
Relative Humidity Sensors (Space or Duct Mounted)
accessory space humidity sensor (33ZCSENSRH-01) or duct
humidity sensor (33ZCSENDRH-01) is used to measure the
relative humidity of air within the space or return air duct. The
RH reading is used to control the Humidi-MiZer option of the
rooftop unit. For wiring distances up to 500 ft (152 m), use a 3-
conductor, 18 or 20 AWG shielded cable. The shield must be
removed from the sensor end of the cable and grounded at the
unit end. The current loop power for sensor is provided by the
RTU Open controller as 24vdc. Refer to the instructions sup-
plied with the RH sensor for the electrical requirements and
terminal locations. RTU Open controller configurations must
be changed after adding an RH sensor. See Fig. 79 and 80 for
typical RH sensor wiring.
• J4
1 or J4
4 = 24vdc loop power
—
—
• J4
2 or J4
5 = 4-20mA signal input
—
—
NOTE: The factory default for dehumidification control is nor-
mally open humidistat.
56
sensor must be located in the
2
Sensor
A dedicated power
—
2
5. Connect the SIG COM terminal to
6. See Fig. 78.
—
SEN
COM
Connections
—
J4-5
J4-6
2
In
units
7 and 8
—
The
—
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