... :1.volume of storage tank:120L,180L,240L,300L2.pressurized water tank: insulating layer,polyurethane foaming ,thickness:55mm outer shell of ... :12bar3.dust ring gasket :EPDM4.evacuated tube:three-target tube,high boron and silicon,content 3.3,structure,gradual change SS ... use with an auxiliary electric booster as to provide hot water without sunshine.3.Superior heat preservation ensured by one-off ...