Rotary chimney cowl is a device, which, in a dynamic way, uses force of the wind to increase chimney draught. The turbine always rotates in the same direction no matter of the wind strength or its direction. Base type: square, openable. Diameter: Ø150 mm ca. It is to be mounted on gravitation based ventilation chimney duct endings, esspecialy on individual and multi-storey housing. When there are wind fluctuations on the chimney duct ending, caused by its bad location. When there is an unfavorable terrain configuration, with strong and frequent winds. When there is a lack of chimney draught or it is too weak. In order to improve the natural (gravitation) ventilation. This device is not to be used with solid fuel (wood, coal, eco-pea coal) stoves. IBAN: DE 82 8505 0100 0232 0452 32 BIC (SWIFT): WELADED1GRL.