... water tank. Thermosiphon systems work on principal of difference between hot water and cold water. When water in vacuum tubes is heating, ... down at the same time to make the circulation between tubes and tank.Specification:1. inner tank l: food grade sus304-2B ... hail resistance: 25mm8. Optional: heat exchanger (red copper), electric heater (1.5kw, 2kw, 2.5kw, 3kw), assistant tank( 5L, 8L, 12L ...