An installation for hot dip coating a metal strip is provided. The installation includes a device for moving the metal strip along a path, a pot for containing a melt bath and a wiping system including at least two nozzles placed on either side of the path downstream the pot. The wiping system has a box with a lower confinement part confining an atmosphere around the metal strip upstream of said nozzles and an upper confinement part confining the atmosphere around the metal strip downstream of the nozzles, first moving means for vertically moving the lower confinement part with respect to the pot and second moving means for vertically moving the upper confinement part with respect to both the pot and the lower confinement part. The nozzles are vertically movable relative to the pot.