A valve for controlling an air flow, comprising: - a body defining an inlet and an outlet opening (26, 27) for the air flow, - a cylindrical shutter housed inside said body, said shutter being selectively rotatable about an axis, said shutter comprising a surface disposed about said axis, said surface comprising: - a first curved portion (46, 47) shaped eccentrically relative to said axis so as to define, in use and together with said body, a first passage (56, 57) for said air flow; - a second curved portion (47, 46) shaped eccentrically relative to said axis, so as to define, in use and together with said body, a second passage (57, 56) for said air flow; a through hole interposed between said first curved portion (46, 47) and second curved portion (47, 46), and which, in use, fluidly connects, said first passage (56, 57) with said second passage (57, 56), said first passage (56, 57) and said second passage (57, 56) being fluidly connected to said inlet and outlet opening (26, 27) respectively, and wherein said body comprises - a pair of arc-shaped walls (36a, 36b) having relative concavities facing said axis and circumferentially interrupted about said axis; and - a pair of inlet and outlet conduits (37, 38) which have relative inlet and outlet mouths (41, 42) defined respectively by said inlet and outlet opening (26, 27), said arc-shaped walls (36a, 36) and said inlet and outlet mouths (41, 42) defining a cylindrical seat which houses said shutter and is fluidly connected with said inlet and outlet opening (26, 27) through said inlet and outlet conduits (37, 38), said first curved portion (46, 47) defining with one of said arc-shaped walls (36a, 36b) said first passage (56, 57); and said second curved portion (47, 46) defining with one of said arc-shaped walls (36b, 36a) said second passage (57, 56). - a body defining an inlet and an outlet opening (26, 27) for the air flow, - a cylindrical shutter housed inside said body, - a first curved portion (46, 47) shaped eccentrically relative to said axis so as to define, in use and together with said body, a first passage (56, 57) for said air flow; - a second curved portion (47, 46) shaped eccentrically relative to said axis, so as to define, in use and together with said body, a second passage (57, 56) for said air flow; a through hole interposed between said first curved portion (46, 47) and second curved portion (47, 46), and which, in use, fluidly connects, said first passage (56, 57) with said second passage (57, 56), said first passage (56, 57) and said second passage (57, 56) being fluidly connected to said inlet and outlet opening (26, 27) respectively, and wherein said body comprises - a pair of arc-shaped walls (36a, 36b) having relative concavities facing said axis and circumferentially interrupted about said axis; and - a pair of inlet and outlet conduits (37, 38) which have relative inlet and outlet mouths (41, 42) defined respectively by said inlet and outlet opening (26, 27), said arc-shaped walls (36a, 36) and said inlet and outlet mouths (41, 42) defining a cylindrical seat which houses said shutter and is fluidly connected with said inlet and outlet opening (26, 27) through said inlet and outlet conduits (37, 38),