Multiway valve, comprising a first valve and a second valve integrally connected with each other, the first and second valves each one comprising: a valve body (10, 200) comprising a user port, a source port (1011, 1021) and an intermediate chamber (18, 31) arranged between the user port (1013, 1023) and the source port (1011, 1021) and a shutter (17, 30) tightly housed inside the intermediate chamber (18, 31) and provided with a passage orifice passing through the shutter, the multiway valve further comprising movement means (11, 21) that allow the shutter of the first and of the second valves to be integrally moved, between a closed position where the passage orifice (20, 32) of each shutter faces the inner walls of the respective intermediate chamber (18, 31) and an open position where the fluid passage between the user port and the source port is allowed through the passage orifice (20, 32), characterized in that the valve body of the first valve comprises a further source port and only two sealing seats (18a, 18b) obtained on inner faces of the intermediate chamber arranged at the source ports of said first valve and wherein the shutter is in contact with the sealing seats by the interposition of sealing rings (19a, 19b), such to prevent the fluid from escaping between the source ports (1011, 1012) and the inside of the intermediate chamber and in that the first valve comprises a by-pass duct formed in the shutter opening at one end on the outer surface of the shutter and at the opposite end to the passage orifice of the first valve, said bypass duct being such that, also with the shutter in the closed position, the intermediate chamber, the passage orifice, the duct, the source port and the user port of the first valve are in fluid communication, wherein the sealing rings (19a, 19b) are provided only at the source ports, the fluid coming from the user port being able to flood the intermediate chamber, fill the passage orifice and flow, through said by-pass duct in the source port. a valve body (10, 200) comprising a user port, a source port (1011, 1021) and an intermediate chamber (18, 31) arranged between the user port (1013, 1023) and the source port (1011, 1021) and a shutter (17, 30) tightly housed inside the intermediate chamber (18, 31) and provided with a passage orifice passing through the shutter, the multiway valve further comprising movement means (11, 21) that allow the shutter of the first and of the second valves to be integrally moved, between a closed position where the passage orifice (20, 32) of each shutter faces the inner walls of the respective intermediate chamber (18, 31) and an open position where the fluid passage between the user port and the source port is allowed through the passage orifice (20, 32), characterized in that the valve body of the first valve comprises a further source port and only two sealing seats (18a, 18b) obtained on inner faces of the intermediate chamber arranged at the source ports of said first valve and wherein the shutter is in contact with the sealing seats by the interposition of sealing rings (19a, 19b), such to prevent the fluid from escaping between the source ports (1011, 1012) and the inside of the intermediate chamber and in that the first valve comprises a by-pass duct formed in the shutter opening at one end on the outer surface of the shutter and at the opposite end to the passage orifice of the first valve, said bypass duct being such that, also with the shutter in the closed position, the intermediate chamber, the passage orifice, the duct, the source port and the user port of the first valve are in fluid communication, wherein the sealing rings (19a, 19b) are provided only at the source ports, the fluid coming from the user port being able to flood the intermediate chamber, fill the passage orifice and flow, through said by-pass duct in the source port.