solar water heater : certification:ISO9001,ISO14001,CCC,CE,Solar Keymark solar water heater:heat pipe tube pressure:pressuriz solar water heater: material:1.volume of storage tank:120L,180L,240L,300L2. ... pressure:6bar,test pressure:12bar3.dust ring gasket :EPDM4.evacuated tube:three-target tube,high boron and silicon,content 3.3,structure,gradual ...