Abstract: A combined fan and valve for evacuating air from a space, especially in connection with ventilation of a toilet bowl from odoreous air. The fan wheel (8) of the fan is assembled with a sealing membrane (13). Moreover, the hub 10 of the fan wheel is provided with spindle threads (11) for cooperation with corresponding spindle threads (7) on the output shaft of the drive motor (5). When the motor is started, the fan wheel is lifted from the valve seat and pumps air from the space through the inlet (2) and out through the outlet (3). When the motor stops, the fan wheel will screw itself downwards along the screw (7) under the influence of the gravity in order to bear against the valve seat (4).