... reasonable price beautiful design Manufacture Non-pressurized solar water heater.1,vacuum tube length:47/1500mm,58/18002,vacuum tubes ... 31mm5,Insulation:foaming polyurethane thickness:50mm or 55mm6,Optional electric heater:220v-240v 1500w/3000w7,frame material :202 stainless steel8, ... 3,The electromagnetism or ball valve can perform the water supply automatically,the water in the tank is not sufficient ...