CD-Wxx-00-0 Series Wall Mount CO
2
Transmitter Installation Instructions
5
3. Plug the relay and display module into the 5-pin
(X3) and two 2-pin (X6 and X7) connectors on the
main PCB, shown in Figure 7.
The relay has two setpoint values, the On level and
the Off level. These provide hysteresis and desired
control function. The On level must be higher than the
Off level. When CO
2
concentration is increasing, the
relay closes at the On level and opens when
concentration is reduced to the Off level.
Note:
The default relay setpoints are 1,000 ppm On
and 950 ppm Off. To change these settings,
use the Relay Setpoint Software ACC-CD-S to
enter new values.
Wiring the Temperature Module
Model CD-WA0-00-0 is shipped with a temperature
module. Observing polarity, connect the temperature
output wires to the screw terminals and –
(see Figure 10).
Front
Connect to X3
Connect to X7
Screw Terminal
Sensor
Figure 10: Temperature Module (Front View)
Setup and Adjustments
Commissioning
Johnson Controls CO
2
transmitters come calibrated for
the following:
•
output signal (0 to 10V) proportional to
CO
2
concentration (0 to 2,000 ppm)
•
altitude range of 0 to 1,969 ft (0 to 600m) above
sea level without compensation
•
default relay output trigger point of 1,000 ppm
Altitude Compensation
The sensors are calibrated for an altitude of 984 ft
(300m) above sea level and are intended for
applications within the range of 0 to 1,969 ft
(0 to 600m) without compensation.
For altitudes above 1,969 ft (600m) where optimum
accuracy of the CO
2
concentration measurement is
essential, modify the Building Automation System
(BAS) controller’s Analog Input (AI) ranging to
compensate for sensor placement at other than the
standard calibration altitude.
To do this, reset the 2,000 ppm value using the
controller’s Compensation Factor (CF) shown in
Figure 11 or Figure 12, as follows:
Corrected Value = CF x 2,000
For example, if the sensor is situated at an altitude of
3,000 ft (914.4m) above sea level, the CF is 1.10
(see Figure 11 or Figure 12).
The new value is calculated as follows:
Corrected Value = (1.10)(2,000 ppm) = 2,200 ppm
0 1,000 2,000 3,000 4,000 5,000 6,000 7,000
CF
Altitude (Feet)
0.90
0.95
1.00
1.05
1.10
1.15
1.20
1.25
1.30
Figure 11: Altitude Compensation in Feet above Sea Level
