38
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.
Wiring the Indoor Air Quality Sensor: For each sensor,
use two 2--conductor 18 AW G (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) t erminals on the
sensor. See Fig. 47. Connect the 4--20 mA terminal to the
RTU Open controller at J4--2 and connect t he SIG COM
terminal to the RTU Open controller at J4--3. See Fig. 64.
SEN
COM
J4-2
J4-3
IAQ Sensor
24 VAC
C08462
Fig. 64 -- RTU Open Controller / Indoor CO
2
Sensor
(33ZCSPTCO2--01 or 33ZCSPTCO2LCD--01)
Connections
Outdoor Air Quality Sensor
(P/N 33ZCSPTCO2--01 or 33ZCSPTCO2LCD--01
plus weatherproof enclosure —
The outdoor air CO
2
sensor is designed to monitor carbon
dioxide (CO
2
) levels in the outside ventilation air and
interface with the ventilation damper in an HVAC system.
The OAQ sensor is packaged with an outdoor cover. See
Fig. 49. The outdoor a ir CO
2
sensor must be located in the
econom izer outside air hood.
Wiring the Outdoor Air CO
2
Sensor: A dedicated
power 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 connecte d 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) t erminals on the
OAQ sensor. See Fig. 49. Connect the 4 to 20 mA
terminal to the RTU Open controller at J4--5. Connect the
SIG COM terminal to RTU Open J4--6. See Fig. 65.
SEN
COM
J4-5
J4-6
OAQ Sensor
24 VAC
C11086
Fig. 65 -- RTU Open Controller / O utdoor CO
2
Sensor
(33ZCSPTCO2--01 or 33ZCSPTCO2LCD--01)
Connections
Space Relative Humidity Sensor or Humidistat —
Humidi--MiZer
R
System Control Wiring: In units
equipp ed with the Hu midi--MiZer optio n ther e are two loos e
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 humidis tat or
thermidistat on an electromech anical unit. On RTU Open
controller equipped units these wires must be connected to
J11--7 and 8 to allow the Open boar d to operate the
dehumid ificatio n function for the unit. D is co nn ect the J 11
Phoenix style connector from the board and use the plug
screws to secure the wires as follow s : secur e the PN K /B LK
wires at pin 7 and the PNK wires at pin 8, and then
reconnect the plug to the board at J1 1.
Relative Humidity Sensors (Space or Duct Mounted):
The accessory space humidity sensor (33ZCSENSRH-02)
or duc t humidity sensor (33ZCSENDRH-02) 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 c able and grounded at the unit
end. The current loop power for sensor is provided by the
RTU Open c ontroller as 24vdc. Re f er to the instructi ons
supplied with the RH sensor for the electrical
requirements and terminal locations. RTU Open controller
configura tions must be changed after adding an RH
sensor. See Fig. 66 and 67 for typical RH sensor wiring.
S J4--1 or J4--4 = 24vdc loop power
S J4--2 or J4--5 = 4--20mA signal input
NOTE: The factory default for dehumidification control
is normally open humidistat.
SW2
12345 6
ON
Io
Vin
Gnd
Vo
MOUNTING
HOLES
WIRING
OPENING
Vin - J4-1 or J4-4 24Vdc
Io - J4-2 or J4-5 -20mA output
C11087
Fig. 66 -- Space Relative Humidity Sensor T ypical Wiring
50TC
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