A multiway valve that may include a generally cylindrical shaped hollow valve body having at least one handling opening and a plurality of through openings made on the outer wall of the valve body and defining a first group of connecting openings and a second group of connecting openings. A handling element may be pivotally disposed in the valve body and include at least two first through radial openings made on the outer wall of the cartridge. A tubular shaped fluid mechanics insert may be housed inside the cartridge, and may have a second radial opening to let a fluid flow. The fluid mechanics insert may also include a cell formed inside the cavity of the insert to define a homogeneous fluid flow rate.