... 0.31mm5,Insulation:foaming polyurethane thickness:50mm or 55mm6,Optional electric heater:220v-240v 1500w/3000w7,frame material :202 stainless steel8 ... The electromagnetism or ball valve can perform the water supply automatically,the water in the tank is not sufficient ,the ... the tap water flow in the tank ,if the water is full,it will close the valve automatically solar tube for solar water heater use