... :Compact Non-pressure Solar Water Heater relies on desity of the water, cold water down, hot water up, ... tank flows down to the collectors.Specifications:1. Material of inner water tank: 0.31mm,/ o.4mm/ 0 ... steel or galvanized steel plate or alumminum alloy.6. Angle of bracket: 0°,25°, 38°, 45° 7. Reflector: ... 70% balance paid via B/L copy), or Letter of Credit(L/C) at sight Three target vacuum tube