... vacuum tube .Split solar water heater can operate with pressure up to 0.6Mpa can be combined with existing energy source storage do not need be ... .2-2.0mm, single copper coil or double copper coil water tank out thickness: SUS304 2B or galvanized steel,0.3-0 ... .2-2.0mm, single copper coil or double copper coil water tank out thickness: SUS304 2B or galvanized steel,0.3-0 ...