... Manufacturer for more than 14years. vacuum tube solar water heater1,vacuum tube length:47/1500mm,58/18002,vacuum tubes:15pcs,18pcs,20pcs,24pcs, ... principle.1,The high quality vacuum tubes ansorb the solar ultraviolet ray;then heat the cold water in the vacuum tube2,The hot ... heater element with terminator..5,Heat exchanger:20m long,12mm diameter,1mm thickness coppper pipe.Feature:1,Pipeline is made ...