Specifications

5
INDOOR AIR QUALITY CO
2
SENSOR INSTALLATION
(IAQ) — The indoor air quality sensor accessory monitors
carbon dioxide (CO
2
) levels. This information is used to moni-
tor IAQ levels. Three types of sensors are provided. The wall
sensor can be used to monitor the conditioned air space.
Sensors use infrared technology to measure the levels of CO
2
present in the air. The wall sensor is available with or without
an LCD readout to display the CO
2
level in ppm.
The CO
2
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 CO
2
sensor for electrical require-
ments and terminal locations.
To accurately monitor the quality of the air in the condi-
tioned air space, locate the sensor near a return air grille (if
present) so it senses the concentration of CO
2
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 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
— To wire the sensors
after they are mounted in the conditioned air space, see Fig. 6
and the instructions shipped with the sensors. 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) ter-
minals on the sensor. Connect the 4-20 mA terminal to terminal
IAQ (RED) and connect the SIG COM terminal to terminal
GND (BRN).
2
3
45
61
SW1
SEN
BRN (GND)
BLU (SPT)
RED(+)
WHT(GND)
BLK(-)
CCN COM
SENSOR WIRING
2
3
45
61
SW1
SEN
SET
Cool Warm
BRN (GND)
BLU (SPT)
RED(+)
WHT(GND)
BLK(-)
CCN COM
SENSOR WIRING
JUMPER
TERMINALS
AS SHOWN
BLK
(T56)
Fig. 2 — Space Temperature Sensor
Typical Wiring (33ZCT55SPT)
Fig. 3 — Space Temperature Sensor
Typical Wiring (33ZCT56SPT)
VAC
24 VAC
BLACK (-)
WHITE (GND)
RED (+)
BLACK (-)
WHITE (GND)
RED (+)
CCN
COM
J2
(COM)
COM
CCN-
GND
CCN+
T58 SENSOR
J6-6 SDT (COM)
J4-3 (24 VAC)
FIELD WIRING
Fig. 4 — T58 Communicating Sensor
Typical Wiring (33ZCT58SPT)