| 摘要 |
A passive ventilation device comprises a ventilation terminal 10 for mounting on a roof component 2 of an enclosure 3, the terminal providing first and second pathways between an interior of the enclosure and the exterior, the two pathways each comprising an inlet and outlet and configured to operate substantially independently of one another in at least one mode, the device switchable between the at least one mode and a heat recovery mode where a quantity of the extract airflow is mixed with the supply airflow within the device for re-circulation into the enclosure. A telescopic cylindrical duct arrangement comprising an outer duct 12 with openings 18 and an inner duct 13 with openings 20 allows the first and second pathways to be independent of one another when the openings 18, 20 are out of alignment; in the heat recovery mode the openings 18, 20 are in alignment so that the first pathway merges with the second pathway. Both pathways may behave as extract pathways, and a fan 37 may be used to enhance the heat recovery mode. |
