A radiant body comprising a plurality of base modules which are contiguous and with a mutual distance, to form the radiant body having a length, each base module comprising: - at least one tubular element with a mainly longitudinal extension, internally hollow, to configure a duct provided with two ends (12, 13); - a first head and a second head, associated stably to the corresponding ends (12, 13) of the tubular element; each head (14, 15) comprising a body configured with an internally hollow "T" shape to form a transit channel defined by a first, second and third path (16, 17, 18); the first and second path (16, 17) facing each other, coaxial and leading outside in respective side walls (14p, 15p), the first and second path (16, 17) being positioned at right angles to the central third path; the third central path being associated with the tubular element, - a pair of junction bodies (20, 21) with a tubular cross-section for the support, above and below, and for the connection in a sealed fashion of the base modules; each junction body (20, 21), engaging a corresponding first or second head of each base module at the two upper paths (16, 17) of the base modules arranged side by side; each junction body (20, 21) being hollow inside and provided with a plurality of openings positioned radially along the relative cylindrical surface, at a distance from each other equal to the distance of the base modules; the openings being positioned, in use, facing the third central path; each first and second head being configured for define an housing zones of sealing members 40, characterised in that each junction body (20, 21) is monolithic and wherein the sealing members are bilaterally arranged on each of the first and second head so as to create a direct seal between the first or second head and the section of the corresponding junction body (20, 21). - at least one tubular element with a mainly longitudinal extension, internally hollow, to configure a duct provided with two ends (12, 13); - a first head and a second head, associated stably to the corresponding ends (12, 13) of the tubular element; each head (14, 15) comprising a body configured with an internally hollow "T" shape to form a transit channel defined by a first, second and third path (16, 17, 18); the first and second path (16, 17) facing each other, coaxial and leading outside in respective side walls (14p, 15p), the first and second path (16, 17) being positioned at right angles to the central third path; the third central path being associated with the tubular element, - a pair of junction bodies (20, 21) with a tubular cross-section for the support, above and below, and for the connection in a sealed fashion of the base modules; each junction body (20, 21), engaging a corresponding first or second head of each base module at the two upper paths (16, 17) of the base modules arranged side by side; each junction body (20, 21) being hollow inside and provided with a plurality of openings positioned radially along the relative cylindrical surface, at a distance from each other equal to the distance of the base modules; the openings being positioned, in use, facing the third central path; each first and second head being configured for define an housing zones of sealing members 40, characterised in that each junction body (20, 21) is monolithic and wherein the sealing members are bilaterally arranged on each of the first and second head so as to create a direct seal between the first or second head and the section of the corresponding junction body (20, 21).