Bryant 551J }

requirements and terminal locations. See Fig. 47 for

typical CO2sensor wiring schematic.

87654321

24 VAC

24 VDC

NC ALARM

RELAY

CONTACTS

COM

}

0-10VDC

SIG COM

4-20mA

J3 J4

C08635

Fig. 47 --Indoor/Outdoor Air Quality (CO2)Sensor

(33ZCSENCO2) --Typical Wiring Diagram

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 CO2

leaving the space. The sensor should be mounted in a

location to avoiddirect 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.

Wiring the Indoor Air QualitySensor —

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 connectthe sensor to the control, identify the positive

(4 to 20 mA) and ground (SIG COM) terminals on the

sensor. See Fig. 47. Connect the 4--20 mA terminal to

RTU--MP J4--2 and connect the SIG COM terminal to

RTU--MP J4--3. See Fig. 48.

SEN

COM

J4-2

J4-3

IAQ Sensor

24 VAC

C08462

Fig. 48 --RTU--MP / IndoorCO2Senso r

(33ZCSENCO2) Connections

Outdoor Air Quality Sensor (PNO 33ZCSENCO2 plus

weatherproof enclosure) — The outdoor air CO2sensor is

designed to monitor carbon dioxide (CO2) levels in the

outside ventilation air and interface with the ventilation

damper in an HVACsystem. The OAQ sensoris packaged

with an outdoor cover. See Fig. 49. The outdoor air CO2

sensor must be located in the economizer outside air hood.

COVER REMOVED SIDE VIEW

C07135

Fig. 49 --Outdoor Air Quality Sensor Cover

Wiringthe Outdoor Air CO2Sensor — 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 connected to the power supply

and terminals1 and 2.

To connectthe sensor to the control, identify the positive

(4 to 20 mA) and ground (SIG COM) terminals on the

OAQ sensor. See Fig. 47. Connect the 4 to 20 mA

terminal to RTU--MP J4--5. Connect the SIG COM

terminal to RTU--MP J4--6.See Fig. 50.

SEN

COM

J4-5

J4-6

OAQ Sensor/RH Sensor

24 VAC

C08463

Fig. 50 --RTU--MP / OutdoorCO2Se nsor

(33ZCSENCO2) Connections

551J