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The casing of the fan unit is made of galvanized steel. The fan unit is equipped with a removable bottom cover for easy installation and
maintenance. It is attached with screws. Heat- and sound-insulation made of non-flammable material. The round connecting spigots are
rubber sealed.
Inside the fan unit there are two mixed type duct fans with energy efficient motors. The fan motors have built-in controls. The low-noise
motors with ball bearings with specially selected grease ensure maintenance-free operation of the fan.
When the unit is in operation, one of the fans is always running, with the second fan as a backup. Depending on the operation algorithm
of the control automatics, the fans can be switched on alternately at different time intervals. This ensures uninterrupted ventilation: in
case of failure of one fan, the second one automatically switches on. Switching modes is carried out using a controller, which is not
included in the basic delivery set and must be ordered separately.
In order to prevent air backflow through a non-functioning fan, a swivel damper is installed inside the casing.
When one of the fans is switched on, the damper rotates due to the air flow from the fan and closes the duct of the inoperative fan. The
main design elements of the fan unit are shown in the figure below.
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5
1
2
3
4
5
6
DESIGN AND OPERATING PRINCIPLE
1 – swivel damper
2 – duct fan
3 – fan terminal boxes
4 – mounting brackets;
5 – removable service panel;
6 – inlet and outlet spigots;
7 – cable glands on the unit casing;
8 – safety cables to prevent the service panel from falling.