... ×1500 Φ58×1800 Tube (pcs) 12 / 15 /18 / 20 / 25 / 30 Vacuum Tube Borosilicate glass, red copper heat pipe, aluminum ... of heat pipe solar collector, storage water tank, workstation system, related accessories and interconnecting pieces, etc.Heat Pipe Solar ... gauge, expansion vessel, check valve, etc. 2) More intelligent system operation, when temperature discrepancy between collector medium and water in ...