A heat recovery system comprising: - an exhaust duct, - a heat exchanger for the exchange of heat between a hot gas coming from the exhaust duct and a liquid coolant, comprising at least one fluid connection (6.1) for entry/exit of the liquid coolant, - a valve actuated through a shaft for opening or closing the passage of hot gas through the heat exchanger, - an actuator comprising a drive rod (7.2) actuated by a substance the specific volume of which changes in the event of changes in temperature, the actuator further comprising: - an inlet/outlet port (7.1) for the entry/exit of a fluid; - an internal chamber (7.4) in fluid communication with the inlet/outlet port (7.1) and in thermal communication with the substance such that in operating mode, the substance is in thermal communication with the fluid entering the internal chamber (7.4) through the inlet/outlet port (7.1); - a metal fluid coupling device, attached at a first fluid inlet/outlet (1.1) by means of welding to the at least one fluid connection (6.1) of the heat exchanger and at a second fluid outlet/inlet (1.2) to the inlet/outlet port (7.1) of the actuator such that a fluid connection is established between the inlet/outlet port (7.1) of the actuator and the fluid connection (6.1) of the heat exchanger through the fluid coupling device, wherein the metallic fluid coupling device is made of stamped metal sheet, wherein the metallic fluid coupling device comprises a plurality of parts, and wherein the drive rod (7.2) of the actuator is connected with the shaft of the valve for the actuation thereof according to the temperature of the liquid coolant. - an exhaust duct, - a heat exchanger for the exchange of heat between a hot gas coming from the exhaust duct and a liquid coolant, comprising at least one fluid connection (6.1) for entry/exit of the liquid coolant, - a valve actuated through a shaft for opening or closing the passage of hot gas through the heat exchanger, - an actuator comprising a drive rod (7.2) actuated by a substance the specific volume of which changes in the event of changes in temperature, the actuator further comprising: - an inlet/outlet port (7.1) for the entry/exit of a fluid; - an internal chamber (7.4) in fluid communication with the inlet/outlet port (7.1) and in thermal communication with the substance such that in operating mode, the substance is in thermal communication with the fluid entering the internal chamber (7.4) through the inlet/outlet port (7.1); - an inlet/outlet port (7.1) for the entry/exit of a fluid; - an internal chamber (7.4) in fluid communication with the inlet/outlet port (7.1) and in thermal communication with the substance such that in operating mode, the substance is in thermal communication with the fluid entering the internal chamber (7.4) through the inlet/outlet port (7.1); - a metal fluid coupling device, attached at a first fluid inlet/outlet (1.1) by means of welding to the at least one fluid connection (6.1) of the heat exchanger and at a second fluid outlet/inlet (1.2) to the inlet/outlet port (7.1) of the actuator such that a fluid connection is established between the inlet/outlet port (7.1) of the actuator and the fluid connection (6.1) of the heat exchanger through the fluid coupling device, wherein the metallic fluid coupling device is made of stamped metal sheet, wherein the metallic fluid coupling device comprises a plurality of parts, and wherein the drive rod (7.2) of the actuator is connected with the shaft of the valve for the actuation thereof according to the temperature of the liquid coolant.