... 8-10 per hole 3. 15Years Warranty for vacuum tu Non-pressure solar water heaters(ss)1.CE,ISO9001,CCC, 2. Anti-freezen ... and faster heating. Advanced exh-aust work Arts, the heat collector tube to a smaller loss of reduction.Super super frame ... advance: the use of more safe, non-troubled waters, anti-burst, antifreeze, E-nrichment process.Collector device:φ47×1500,φ58×1800Nano-nuclear ...