Thermal system with rankine circuit

A thermal system, in particular for a motor vehicle, including:

• a Rankine cycle heat recovery device including a Rankine circuit, in which a Rankine fluid circulates, the Rankine circuit including a first heat exchanger in which the Rankine fluid recovers heat from a heat source, an expander, a condenser, and a first pump,
• a cooling device including a cooling circuit in which a refrigerant circulates, said cooling circuit including a second heat exchanger in which the refrigerant gives heat to a cold source, a second pump, and a third heat exchanger with a device to be cooled and that comprises a pressure regulating device that regulates the pressure in the Rankine circuit, said pressure regulating device including an enclosure delimiting a space and housing a movable part separating the space into first and second chambers, the first chamber communicating with the Rankine circuit and the second chamber communicating with the cooling circuit.