Abstract: A ventilation device is provided with a plurality of fans, each of the fans is rotated in a different direction to one another so that exhaust of inside air and intake of outside air can be conducted at the same time. Preferably, the ventilation device includes a tubular body extending between the inside and outside of the room where the tubular body installs a first fan therein at inside of the room and a third fan therein at about a middle thereof, an air duct for establishing an air flow path between inside and outside of the room, a fan compartment having a second fan therein where the second fan is inclined in a direction intermediate of a longitudinal direction of the air duct and a direction toward the first fan. The fan compartment establishes a first air passage to the tubular body through a first air hole and a second air passage to the air duct through a second air hole.

Abstract: An apparatus, for installing a ventilation fan, highly effective for preventing dust, gas or the like from coming in a room has been provided by the present invention. An apparatus 1 for installing a ventilation fan comprises a L-shaped housing 5, for fixing a ventilation fan 3 therein, having an inside opening 7 positioned inside a wall W, and an outside opening which looks down and is positioned outside the wall W. The inside opening 7 is provided with a filter 11 for exhaust able to be slide vertically, and able to be taken in and out from the housing 5. Further, the inside opening 7 is covered with a metallic lid 13 able to be open or shut. A filter 15 for absorbed air is provided near the outside opening 9. The filter 15 is able to slide horizontally. The ventilation fan F is rotatable clockwise and counterclockwise. The filter 15 for absorbed is installed in absorbing air. The filter 11 for exhaust is installed in exhausting air.