... 2.Anti-freezen & pressurized 3.10 years warranty Vacuum tube solar collecotr a. Module design, arbitrary combination, harmonize ... 1.5Kw to 3Kw collector1) Reliable, efficient, twin-glass evacuated tubes2) Red copper(TU1) heat pipes for rapid heat ... 24-5818SC-H-30-5818Length of Tube1800mmOuter Diameter of Tubeφ58mmTube Quantity1518202430Manifoldcasing material,Aluminum Alloy,Thickness,1.8mm,Insulating ...