Abstract: The invention relates to a connecting valve (10), comprising at least four connections (101 104) for fluid circulation tubes, which comprises a single control member (120) designed to allow the selective creation of several configurations of communication pathways within the valve, between certain tube connections; these configurations notably include: • a first configuration in which a first tube connection, referred to as “main inlet” (103) is placed in communication with only a second tube connection, referred to as “main outlet” (104), • a second configuration in which the main inlet is placed in communication with a third tube connection (101), referred to as “bypass outlet”, and a fourth tube connection (102) referred to as “bypass return” is placed in communication with the main outlet, and • a third configuration in which the main inlet is placed in communication both with the main outlet and with the bypass outlet, and the bypass return is placed in communication with the main outlet.