The present invention relates to a centrifugal fan assembly and a HVAC-system, comprising a housing, a blower wheel comprising a plurality of fan blades, the blower wheel being rotatably mounted in the housing and constructed to generate an airflow flowing axially into the blower wheel and radially out from the blower wheel, a guiding vane device including a plurality of guiding vanes, the guiding vane device being coupled to the blower wheel and configured to guide the airflow into the blower wheel.