Fan Components and Material Properties The CRDF series of vertical-centric roof-type radial fans are made of galvanized sheet steel with the body, mounting plate and fan wheels of the models . All models have an external rotor motor with closed structure. The device is capable of handling air at max.40ºC.

The fan blades are aerodynamically curved and provide regular flow. The fans are composed of backward sloping and infrequently arranged fins.

CRDF roof fans are particularly advantageous in vertical applications due to the fact that air cannot be absorbed horizontally. Thanks to the aerodynamic wing structure, they work quietly. Speed can be adjusted with speed control devices. Since the rainwater is easily evacuated, water ingress is prevented from entering the chimney.

Optional control devices can be provided. Speed control can be done with linear voltage regulator in 1~phase products (see BSC accessory). Speed control with frequency inverter can be done in 3~phase products (see VHAN accessory)

In order to increase the air quality of indoor spaces, it is used in situations where vertical shot is required under conditions where air cannot be disposed horizontally. The CRDF roof fans operate at low volume with an external rotor motor. It is used on the roofs of the places where the air is to be refreshed and the chimneys on the bathroom and wc roofs of the buildings which are opened to the common shaft.