An AHU comprises a cabinet, a heat exchanger and a blower. The cabinet has an air inlet opening and an air outlet opening, panels are provided on sides of the cabinet forming an air flow path for air flowing through the air handling unit between the air inlet opening and the air outlet opening. The heat exchanger is disposed in the air flow path and adapted to conduct heat exchange between air passing through the air flow path and a working medium flowing in the heat exchanger. The heat exchanger includes an inlet header for supplying the working medium and an outlet header for collecting the working medium. The heat exchanger is slanted with respect to a side of the cabinet such that the inlet header and the outlet header extend through one of the sides of the cabinet for providing access to the inlet header and the outlet header from the one of the sides of the cabinet. The blower is vertically disposed relative to the heat exchanger in the cabinet for forcing air to flow through the air flow path.