Can be VCB control unit used to control the direct cooling?
Yes, the VCB control unit can be used to control direct air cooling; however, this is not an ideal solution because the VCB control unit is designed to control the inlet air temperature - and the temperature changes are fast considering the on/off (two-stage) control mode (mainly if the differences between the outdoor and required indoor air temperatures are very small) while the cooling compressor operation (run/stop modes) intervals need to be as long as possible, these intervals are controlled by the control unit preventing the compressor from being switched too often.
So, if the inlet air is quickly cooled down and the compressor is switched off, the new start of the compressor is blocked and the air cooling is not performed during the blocking interval, which results in insufficient supply of cooled air into the ventilated room (not to mention extensive fluctuation of the inlet air temperature). The room air temperature will start rising.
Therefore, if used with direct cooling, it is always recommended to use the compensation sensor and corresponding parameters to compensate the abrupt drop of the required value (from the room temperature) so the required temperature is reached with a delay. Two-stage condensing units are preferred.
For more comfortable control, we recommend using the WebClima control unit featuring cascade temperature control (though the control principles are the same, the room temperature does not change so quickly).
Note: To make the control using the VCB control unit efficient, the minimum inlet air temperature limiter must be set accordingly.