In the instructions for use it is written that the minimum height of the water is 14 cm, which means that half of the pump is out of the water, am I missing something? I have half of the pump outside and half in the water
Yes, that is fine, as long as the pump can take in water, water is drawn in and cools the motor. With a water level that is at the minimum though you must be very careful the pump never runs dry or it will be ruined.