The present invention relates to a plant for the continuous vacuum deposition of a metal coating on a moving substrate, including a vacuum deposition housing (24), at least one sonic vapor-jet coating head (25, 26) connected to an evaporation crucible (9) for containing the coating metal in the form of a liquid (11) via a vapor-feeding duct (20) provided with a dispensing valve (19), and a furnace (1) for melting said metal, wherein said furnace (1) remains at atmospheric pressure while being arranged underneath the lowest portion of the evaporation crucible (9) and connected to the evaporation crucible (9) by at least one automatic feeding duct (8) of the evaporation crucible (9) provided with a feeding pump (6) and by at least one return duct (8A, 18) for the liquid metal, which is optionally provided with a valve (16, 17), a means for adjusting the feeding pump (6) also being provided for adjusting a predetermined liquid-metal level in the evaporation crucible (9), characterized in that the plant comprises, in each of said feeding and return ducts (8; 8A, 18), a so-called thermal-valve area (7, 13, 15) provided with a heating device and a cooling device in order to obtain a controlled temperature that is independent from that of the melting furnace (1), as well as from that of the remaining portion of said ducts (8, 8A, 18) and of the evaporation crucible (9), in order to melt or solidify the metal at this location.