Fan unit for a ventilator

A fan unit for a ventilator, wherein the fan unit comprises a housing with a suction connector which forms an inlet duct for a suction-side inflow of a fluid into the housing, and a pressure connector which forms an outlet duct for a pressure-side outflow of the fluid from the housing, as well as a fan impeller which is mounted rotatably in the housing and is configured and arranged, by way of rotation, to suck in the fluid via the suction connector and to convey it through the inlet duct into the housing, and to eject the fluid again via the pressure connector and to convey it through the outlet duct out of the housing, the suction connector comprising at least one flow guiding element on its inner face which faces the inlet duct and defines an inlet duct nominal diameter (DN), the at least one flow guiding element setting an inlet duct internal diameter (DI) which differs at least in sections from the inlet duct nominal diameter (DN).