A radiator, comprising - at least two connection cross-sections, - at least two collection channels (3, 4), and - a plurality of heating channels, wherein by means of the connection cross-sections, the radiator can be connected to a flow and a return of a heating system providing a heating medium, wherein the heating channels are fluidically connected to the collection channels so that the heating medium can flow from one of the collection channels through the heating channels into the other collection channel, wherein at least one heating channel cooperates at least indirectly in a heat-transferring manner with at least one convector plate, wherein at least one heating duct comprises a multiplicity of individual convector plates which are arranged distributed along a longitudinal axis of the heating channel and are connected to a wall of the heating channel in a force-transmitting manner, wherein each of the convector plates comprises a base in contact with the heating channel and at least one leg which, starting from the base, extends in a direction away from the heating channel, wherein the at least one leg has a stiffening portion at an end facing away from the base, wherein a free end of the stiffening portion is arranged on a side of the leg facing away from the base, wherein a respective convector plate is formed from aluminum and the heating channel is formed from steel or aluminum, characterized in that each of the convector plates has a Z-shape, wherein each convector plate has a single, planar base with which it is in contact with the heating channel, wherein the at least one leg has at least one stiffener (15, 23), preferably a multiplicity of stiffeners (15, 23), which extends or extend in a vertical direction of the leg, wherein the at least one stiffener, starting from the leg, projects or project to the base and stiffens or stiffen in this manner a kink between the base and the leg. - at least two connection cross-sections, - at least two collection channels (3, 4), and - a plurality of heating channels, wherein the heating channels are fluidically connected to the collection channels so that the heating medium can flow from one of the collection channels through the heating channels into the other collection channel, wherein at least one heating channel cooperates at least indirectly in a heat-transferring manner with at least one convector plate, wherein at least one heating duct comprises a multiplicity of individual convector plates which are arranged distributed along a longitudinal axis of the heating channel and are connected to a wall of the heating channel in a force-transmitting manner, wherein each of the convector plates comprises a base in contact with the heating channel and at least one leg which, starting from the base, extends in a direction away from the heating channel, wherein the at least one leg has a stiffening portion at an end facing away from the base, wherein a free end of the stiffening portion is arranged on a side of the leg facing away from the base, wherein a respective convector plate is formed from aluminum and the heating channel is formed from steel or aluminum, characterized in that each of the convector plates has a Z-shape, wherein each convector plate has a single, planar base with which it is in contact with the heating channel, wherein the at least one leg has at least one stiffener (15, 23), preferably a multiplicity of stiffeners (15, 23), which extends or extend in a vertical direction of the leg, wherein the at least one stiffener, starting from the leg, projects or project to the base and stiffens or stiffen in this manner a kink between the base and the leg.