Fan for air handling unit (AHU) assembled from several parts with radial and axial retainers

An Air Handling Unit, AHU, having an extract air channel comprising:

• at least one extract air inlet for guiding extract air from a building to the outside through at least one extract air outlet and/or a supply air channel comprising at least one supply air inlet for guiding supply air from the outdoor into a building through at least one supply air outlet adapted to be connected to an air ventilation ducting system,
• said AHU further comprising at least one fan in order to induce a flow in the air ventilation ducting system when connected, said fan being assembled from a front disc, a back plate and a plurality of fan blades being manufactured as separate units, said front disc having a hole where through air enters and said fan blades being arranged to provide a radial flow in a radial direction of the fan or mixed flow from the fan, said fan blades having a leading edge arranged closer to the center axis of the fan than a trailing edge arranged further away from the center axis, said fan blades further having an upper edge comprising a multitude of upper attachment protrusions designed to fit into corresponding front disc indentations in the front disc and a lower edge comprising a multitude of lower attachment protrusions designed to fit into corresponding back plate indentations in the back plate, said fan blade further having a blade body with a first side and a second side,
• said fan blade comprising at least two upper attachment protrusions and at least two lower attachment protrusions designed to protrude through the corresponding front disc indentations and the corresponding back plate indentations respectively so as to form at least two front disc axial retainers and at least two back plate axial retainers, each of said two upper attachment protrusions and at least two lower attachment protrusions being provided with an axial locker on the distal end of the upper and lower attachment protrusions respectively protruding through the corresponding front disc indentations and back plate indentations respectively in order to provide a retaining force between the front disc and the back plate while at least one other upper attachment protrusion and one other lower attachment protrusion are designed to cooperate with front disc indentations and back plate indentations respectively so as to form at least one front disc radial retainer and at least one back plate radial retainer,
• wherein said at least two front disc axial retainers and said at least two back plate axial retainers provide retaining forces only in an axial direction retaining the back plate and the front disc at a constant distance from each other in the axial direction, and
• wherein said at least one front disc radial retainer and said at least one back plate radial retainer provide retaining forces only in the radial direction maintaining said fan blade at the same distance and position relative the center axis of the fan.