... for efficient heat transferring and long life span of the solar water heater;6. The insulating layer uses polyurethane bulk ... technology of glass coating, heat efficient, D58 , L1800mm.Qty. of solar tubes12pcs, 16pcs, 18pcs, 20pcs, 24pcs, 30pcs, 36pcs.Inner tank0.4mm ... 95%After-sale services 15 years warranty Specifications of JiXiangQuan Solar Water Heater: ITEM NO.Qty of tubesDiameter of tubesLength ...