Bryant 548J*14D RTU-MP T-56 Sensor Connections, Indoor Air Quality CO2 sensor

SEN J20-1

SEN J20-2

Jumper

SET

SET J20-3

C08461

Fig. 40 - RTU-MP T-56 Sensor Connections

Connect T-59:The T-59 space sensor requires a separate, isolated power supply of 24 VAC. See Fig. 41 for internal connections at the T-59. Connect the SEN terminal (BLU) to RTU-MP J20-1. Connect the COM terminal (BRN) to J20-2. Connect the SET terminal (STO or BLK) to J20-3.

Indoor Air Quality (CO2 sensor) —

The indoor air quality sensor accessory monitors space carbon dioxide (CO2) 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 CO2 present in the space air.

The CO2 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 CO2 sensor for electrical requirements and terminal locations. See Fig. 42 for typical CO2 sensor wiring schematic.

548J*14D

BLK (STO)

BRN (COM)

BLU (SPT)

OR SET SEN

OPB COM- PWR+

24 VAC

J20-3

J20-2SENSOR WIRING

J20-1

POWER

WIRING

H G 24 VAC OR

+ - 24 VDC

+ 0-10VDC

- SIG COM + 4-20mA

NC }ALARM

COM RELAY

NO CONTACTS

2 1 8 7 6 5 4 3 2 1

J3 J4

C08635

NOTE: Must use a separate isolated transformer.

C10291

Fig. 41 - Space Temperature Sensor Typical Wiring

(33ZCT59SPT)

Economizer Controls —

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.

Fig. 42 - 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 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.

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.

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