Where exactly is the fan located?

The fan normally sits at the beginning of a ventilation or cooling tube. If the fresh air intake is possible directly in the outer wall without an additional air supply duct, the fan is also located directly in the outer wall. In most cases this arrangement is feasible. If an additional air supply duct is required (e.g. for air intake via a false ceiling), the fan is located at the end of this duct and thus in turn at the beginning of a ventilation or cooling hose. In special cases, other fan arrangements are also possible.