A centrifugal pump assembly which is provided and designed for use as a circulation pump assembly for heating facilities and air-conditioning facilities, with a pump casing (24; 24'), with an electrical drive motor as well as at least one impeller (38; 38') which is rotatingly driven by this and which is arranged in the pump casing (24; 24'), in which a first suction channel (46; 46') is formed, said first suction channel forming a first flow path from a first suction connection piece (44; 44') to the suction side of the impeller (38; 38'), the first suction connection piece (44; 44') and a delivery connection piece (40; 40') which is formed on the pump casing (24; 24') are directed opposite one another in the direction of a common installation axis, characterised in that the pump casing (24; 24') comprises a receiving space (50; 50') which has a tubular basic shape and which intersects the first suction channel (46; 46') in a manner such that an intersection region results between the first suction channel and the receiving space, wherein the receiving space (50; 50') is connected to a second suction connection piece (58; 82; 110; 116) and in whose inside at least one movable valve element (64; 90; 100; 128) is arranged, said valve element being connected to an actuator (76; 94; 105; 124) and being designed in a manner such that a cross-sectional ratio between the first flow path which extends from the first suction connection piece (44; 44') and a second flow path which extends from the second suction connection piece (58; 82; 110; 116) can be changed by way of a movement of the valve element (64; 90; 100; 128), that the first and the second flow path run out into the receiving space (50; 50') and a section (46b; 46'b) of the first suction channel (46; 46') forms a flow path from the receiving space (50; 50') to the suction side of the at least one impeller (38, 38'), that the longitudinal axis of receiving space (50; 50') extends transversely and in particular normally to a plane, in which the installation axis is situated. characterised in that the pump casing (24; 24') comprises a receiving space (50; 50') which has a tubular basic shape and which intersects the first suction channel (46; 46') in a manner such that an intersection region results between the first suction channel and the receiving space, wherein the receiving space (50; 50') is connected to a second suction connection piece (58; 82; 110; 116) and in whose inside at least one movable valve element (64; 90; 100; 128) is arranged, said valve element being connected to an actuator (76; 94; 105; 124) and being designed in a manner such that a cross-sectional ratio between the first flow path which extends from the first suction connection piece (44; 44') and a second flow path which extends from the second suction connection piece (58; 82; 110; 116) can be changed by way of a movement of the valve element (64; 90; 100; 128), that the first and the second flow path run out into the receiving space (50; 50') and a section (46b; 46'b) of the first suction channel (46; 46') forms a flow path from the receiving space (50; 50') to the suction side of the at least one impeller (38, 38'), that the longitudinal axis of receiving space (50; 50') extends transversely and in particular normally to a plane, in which the installation axis is situated.