CO2 air quality override on dampers and fan speed

If the user connects a CO2 sensor to the input CO2_Sensor, the air quality P control will enabled automatically. The CO2 setpoint is defined by the parameter CO2-01 and the P-band by CO2-02.

Both parameters have the unit parts per million (ppm).

The total proportional band is shifted below the setpoint, as shown in next figure.



The 0...100% control signal will be applied to the fan speed and the mixing dampers as shown in the following picture. The sequences can be set with parameters CO2-03...CO2-06.


Note: The end-point parameters must always have a higher value then the start- point parameters. If both start- and end-point parameters of a sequence are set to “0”, then that particular sequence function will be inactive.



The strategy applies the maximum signal of the temperature and CO2 control to the damper and fan outputs.


Description

Default value

CO2-01: air quality setpoint; 0 = disable internal controller

1000 ppm

CO2-02: air quality P-band

200 ppm

CO2-03: sequence start point air quality override dampers

0 %

CO2-04: sequence end point air quality override dampers

50 %

CO2-05: sequence start point air quality override fan speed

50 %

CO2-06: sequence end point air quality override fan speed

100 %