CIAT AirControl CTA Manuel De Régulation page 80

1.5.14 Free cooling
To authorise Free cooling, certain conditions must be fulfilled:
- The fresh air temperature must be greater than 8.0°C (value adjustable from 20.0 to -5.0°C)
- The fresh air temperature must be below the return (or ambient) air temperature – 3°K
If there is a mixing damper, the percentage of fresh air depends on the cooling request sent by the regulation. A minimum value
of fresh air supply when the unit is stopped is adjustable.
1.5.15 Humidity
The return air or ambient humidity is controlled by one of 3 options:
- In supply only, using a humidifier.
- In dehumidification only, using a cooling coil + heating coil assembly.
- In supply and in dehumidification, using the systems set out above.
Low threshold
alarm
100
50
0
Setpoint -20%
Control using supply
By decreasing the humidity below the setpoint, the control will calculate the requirement needed to constantly maintain this
humidity by an action, via a 0-10V signal, on a modulating humidifier.
The management board sends a summary of the humidifier faults to the pCO3, via a potential-free (dry) contact. In case of a
fault, it stops and an alarm is displayed.
Control using dehumidification
By increasing the humidity above the setpoint, the control will calculate the requirement needed to constantly maintain this
humidity by acting on the cooling coil valve. The heating coil is controlled in order to avoid a drift in the intake temperature.
1.5.16 CO2 air quality
The aim is to regulate the air quality, measured in ppm of CO2, using a duct sensor measuring the return flow.
It is possible to connect sensors using 2 types of signals for the measurement range of 0 to 2000ppm de CO2:
- 0-5V
- 0-10V
This control function acts in order, and depending on availability, on the mixing damper opening value to allow a greater fresh air
rate than on the supply air fan flow rate.
This management is incompatible with pressure regulation in the supply air duct.
Setpoint
SMR
Additional requirement (%)
Band
800 8500
Quality proportional band
Dehumidification requirement (%)
Band
Neutral
Neutral
Setpoint
900
EN - 14
High threshold
alarm
%rH
Return RH
Setpoint +20%
Ambient RH
ppm CO 2