Optimum flow including the outer wall conduct is decisive for the performance of any kitchen air extraction system. With the COMPAIR® flow-Star wall conduct, the pressure of the airflow generated by the hood fan is used simultaneously for opening and closing. The sequence of movements of the maintenance-free, ball-bearing mounted sled installed in the plastic casing with tightly closing stainless steel front plate is controlled by spring magnet mechanics. Blower door results: Both the positive and the negative pressure readings exceed the reference values required by the new German Energy Savings Ordinance (EnEV).