Unit for feeding a reducing solution from the tank to the exhaust duct of an engine

Unit (11) for feeding a reducing solution tank of a vehicle equipped with an endothermic engine, said unit being for feeding a reducing solution from the tank to the exhaust duct of the endothermic engine, said unit comprising a supporting head (13) firmly associatable to an aperture of the reducing solution tank and a heating device (15) for heating the reducing solution contained in the tank, the heating device (15) extending longitudinally from the supporting head (13) and being provided with a duct (17) for a heating fluid, said duct (17) being defined by a side wall (31) which, when the unit (11) is in use, is internally in contact with the heating fluid passing through the duct (17) and externally in contact with the reducing solution present in the tank, wherein at least one portion of the wall (31) of the duct (17) is corrugated and comprises a plurality of ridges (33) and valleys (35), characterized in that the ridges (33) and the valleys (35) are annularly continuous, mutually alternated and regularly distributed both inside and outside the duct.