Pressurized solar water heater 150L Solar keymark, CE, ISO Red copper heat pipe, transfer heat quick 58-1800mm tube 1. Working principle: The pressurized water tank ... Galvanized steelAngle18, 38, 45, 50 degreeVacuum tubeMaterial1.6mm thickness borosilicate glass 3.3Size47-1500mm, 58-1800mm, 70-2000mmAbsorb coatingAL-N-AL ... the heat can be preserved for a longer time. aluminum tube solar water heater