A coil winding system of a hot-rolled product comprising: - a rotating coiler with vertical axis, comprising an outer drum and an inner mandrel coaxial to said outer drum, wherein said outer drum and said inner mandrel delimit an annular interspace, which is closed on the bottom by means of a bottom wall integral with the drum and/or with the mandrel and inside of which the hot-rolled product is placed to wind it in the form of a reel; - means for conveying the hot-rolled product entering the rotating coiler towards said annular interspace, wherein said conveying means are associated with a support frame which is rotationally fixed with respect to said coiler, wherein it comprises means for diverting the hot-rolled product inside said annular interspace from the winding trajectory induced by the rotation of the coiler, wherein said diverting means are placed downstream of said conveying means with respect to the entering movement of the hot-rolled product in the coiler and are suitable to set the radial winding distance of the hot-rolled product relative to the vertical axis of the coiler inside said annular interspace, and wherein said diverting means comprise a diverter element which in use comes into contact with the hot-rolled product and the orientation of which inside the annular interspace is adjustable so as to vary the setting of the radial winding distance characterized in that said diverting means are associated with said support frame, wherein said support frame is movable relative to said coiler and wherein said system comprises means for moving said support frame relative to said coiler, said support frame being movable coaxially to said coiler and in that said support frame is axially hollow and is configured to insert itself at least partially inside said annular interspace receiving coaxially inside it said inner mandrel and wherein said diverting means are associated with a lower portion of said support frame which is intended to insert itself in use inside said annular interspace. - a rotating coiler with vertical axis, comprising an outer drum and an inner mandrel coaxial to said outer drum, wherein said outer drum and said inner mandrel delimit an annular interspace, which is closed on the bottom by means of a bottom wall integral with the drum and/or with the mandrel and inside of which the hot-rolled product is placed to wind it in the form of a reel; - means for conveying the hot-rolled product entering the rotating coiler towards said annular interspace, wherein said conveying means are associated with a support frame which is rotationally fixed with respect to said coiler, wherein it comprises means for diverting the hot-rolled product inside said annular interspace from the winding trajectory induced by the rotation of the coiler, wherein said diverting means are placed downstream of said conveying means with respect to the entering movement of the hot-rolled product in the coiler and are suitable to set the radial winding distance of the hot-rolled product relative to the vertical axis of the coiler inside said annular interspace, and wherein said diverting means comprise a diverter element which in use comes into contact with the hot-rolled product and the orientation of which inside the annular interspace is adjustable so as to vary the setting of the radial winding distance characterized in that said diverting means are associated with said support frame, wherein said support frame is movable relative to said coiler and wherein said system comprises means for moving said support frame relative to said coiler, said support frame being movable coaxially to said coiler and in that said support frame is axially hollow and is configured to insert itself at least partially inside said annular interspace receiving coaxially inside it said inner mandrel and wherein said diverting means are associated with a lower portion of said support frame which is intended to insert itself in use inside said annular interspace.