Temperature sensor GT1R placed in room controlling the sequence in the following order to increase heating by room controller SE1.

1. Close the control valve SV4K gradually against KB refrigeration system to reduce cooling media.

2. Reduce the intake and the exhaust air gradually by closing the damper actuator ST4T1 and ST4T2 for intake air respectively ST4F and ST4F2 of exhaust air from their mechanically adjusted max level to their mechanically adjusted min level to reduce resp. airflow.

3. Open the control valve SV2Vx, gradually against VS heating system to increase the heat media, to keep the setpoint SE1. By decreasing heating demand the control function occurs in reverse order.

Setpoint 21°C ± 4°C

By outdoor temperature undercutting 5° C close the valve SV2Vx, only to the adjusted minimum position.
This is to prevent cold air, which means that if the outdoor temperature drops to below 5° C when the control valve is closed, open it to its minimum position.

Minimum Position is adjustable and initially set it to 20 %.
The intake/exhaust air dampers can be override depending on air quality in the room.
Forced ventilation obtained in the room at elevated CO₂ levels recorded by air quality sensors which means that intake air damper ST4T1 and ST4T2 and exhaust air damper ST4F and ST4F2 open to their mechanically matched max level and remains there as long as air quality sensors register elevated CO₂ concentration.

The intake and exhaust air damper close the dampers to the mode under temperature control when the air quality sensor registers a lower CO₂ content.

Setpoint START 1 000 ppm
Setpoint STOP 800 ppm