complate nonpressurized vacuum tubes solar hot water system1.Tube Size:58*1800 2.Outer tank diameter:480,500 complate nonpressurized vacuum tubes solar hot water systemTube Size:58*1800Outer tank diameter:480,500Inter tank diameter:470,490Tube quantity: 10, 12, 15, 18, 21, 24, 30, 36 piecesAssistant tank capacity: 80 to 120LSolar Water Heating SystemSpecifications:. Inner Tank: SUS304-2B food ...