A hydraulic construction unit includes a centrifugal pump assembly which includes an electrical drive motor and at least one impeller which is driven by the electric drive motor. At least one valve element is arranged such that the valve element is movable by way of a fluid flow which is created by the impeller. At least one section of a wall delimits a flow path in the hydraulic construction unit and is configured to be movable as a moveable section. The movable section of the wall is part of the valve element or is connected to the valve element for movement. The movable section is movable so as to be at least partly effected by friction forces of a fluid flow which runs along the wall.