Extension section Biobe for slot vent valve

An extension section may be required, for example when a vent is to be installed in the frame of an inward opening window with an overlap rebate. If the window reveal connects close to the top frame member, it is sometimes necessary to turn the vent with the air opening facing downward and install an extension section so that the airflow can pass, for example, an overlap rebate. If possible, however, we always recommend turning the vent upward for comfort reasons.