... 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, ... in the tank is not sufficient ,the electromagnetism valve will open its valve,the tap water flow in the tank ,if the ...