Radiator balancing device for connecting a radiator to pipes of a hydronic heating system so that a heating medium can flow from a supply pipe of the hydronic heating system into the radiator and then from the radiator into a return pipe of the hydronic heating system, comprising a housing, wherein the housing has a first connection interface adapted to be connected to the supply pipe of the hydronic heating system, a second connection interface adapted to be connected to a supply connection of a radiator, a third connection interface adapted to be connected to a return connection of the radiator, and a fourth connection interface adapted to be connected to the return pipe of the hydronic heating system, wherein the housing defines a supply flow path extending between the first connection interface and the second connection interface and a return flow path extending between the third connection interface and the fourth connection interface, a first thermal expansion element, wherein the expansion status of the first thermal expansion element depends from the temperature of the heating medium within the supply flow path, a second thermal expansion element, wherein the expansion status of the second thermal expansion element depends from the temperature of the heating medium within the return flow path, a valve having a valve seat provided within the return flow path of the housing and a valve plunger, wherein a change in the thermal expansion status of the second thermal expansion element causes a change in the relative position between the valve plunger and the valve seat of the valve, and a piston positioned between the first thermal expansion element and the second thermal expansion element, wherein the piston acts in combination with the two thermal expansion elements (22, 23) in such a way that a change in the thermal expansion status of the first thermal expansion element impacts the position of the second thermal expansion element and may thereby cause a change in the relative position between the valve plunger and the valve seat of the valve, characterized in that the valve seat is provided by a valve seat element that is screwed into the housing, wherein the screwing position of the valve seat element that provides the valve seat defines a closing temperature of the valve. a housing, wherein the housing has a first connection interface adapted to be connected to the supply pipe of the hydronic heating system, a second connection interface adapted to be connected to a supply connection of a radiator, a third connection interface adapted to be connected to a return connection of the radiator, and a fourth connection interface adapted to be connected to the return pipe of the hydronic heating system, wherein the housing defines a supply flow path extending between the first connection interface and the second connection interface and a return flow path extending between the third connection interface and the fourth connection interface, wherein the housing has a first connection interface adapted to be connected to the supply pipe of the hydronic heating system, a second connection interface adapted to be connected to a supply connection of a radiator, a third connection interface adapted to be connected to a return connection of the radiator, and a fourth connection interface adapted to be connected to the return pipe of the hydronic heating system, wherein the housing defines a supply flow path extending between the first connection interface and the second connection interface and a return flow path extending between the third connection interface and the fourth connection interface, a first thermal expansion element, wherein the expansion status of the first thermal expansion element depends from the temperature of the heating medium within the supply flow path, a second thermal expansion element, wherein the expansion status of the second thermal expansion element depends from the temperature of the heating medium within the return flow path, a valve having a valve seat provided within the return flow path of the housing and a valve plunger, wherein a change in the thermal expansion status of the second thermal expansion element causes a change in the relative position between the valve plunger and the valve seat of the valve, and a piston positioned between the first thermal expansion element and the second thermal expansion element, wherein the piston acts in combination with the two thermal expansion elements (22, 23) in such a way that a change in the thermal expansion status of the first thermal expansion element impacts the position of the second thermal expansion element and may thereby cause a change in the relative position between the valve plunger and the valve seat of the valve, characterized in that the valve seat is provided by a valve seat element that is screwed into the housing, wherein the screwing position of the valve seat element that provides the valve seat defines a closing temperature of the valve. wherein the piston acts in combination with the two thermal expansion elements (22, 23) in such a way that a change in the thermal expansion status of the first thermal expansion element impacts the position of the second thermal expansion element and may thereby cause a change in the relative position between the valve plunger and the valve seat of the valve, characterized in that the valve seat is provided by a valve seat element that is screwed into the housing, wherein the screwing position of the valve seat element that provides the valve seat defines a closing temperature of the valve.