... available 4.Long lifetime. pressurized and split solar water heater:solar collect:The collector absorbs solar energy and transmits it to the water ... , inner: Rock wool with red copper pipe. 8.The standards of vacuum tubes with heat pipe: 14, 16, 18, 20, 24, ... insulation: 72h11.High heat effectiveness: Higher than all glass evacuated solar collector tube by 15 Heat pipe split pressure solar water heater