A fan comprises a frame, a rotor supported by this frame and having a central hub and a number of blades and drive means for rotatably driving the rotor, in addition to a ring to which the end zones of the blades are connected. The ring is assembled from two part-rings of the same form which each consist of a circular strip of sheet material, the free ends of which are mutually connected to form the outer surface of a truncated cone, and a third part-ring which mutually connects the inner edges of the first two part-rings. The end zones of the blades are connected to the third part-ring. The ring has a diameter of more than about 1.50 m. The number of blades amounts to at least eight. The blades are hollow and comprise a framework structure which is provided with a skin connected thereto.