... pre-heated solar water heater with assistant tank Working principle:Pre-heated solar water heater ... ,the three-high vacuum tube,bracket,assistant tank optional parts:A controller:show water level, ... diameter 12mm,thickness 1mm lengh: 30-45m Tank: Inner tank:SUS304 2B food grade stainless steel 0. ... length: 1500mm, 1800mm.Model Absorb area (m²) Water tank capacity (L) 20GP/40GP loading qty (sets) ITM ...