It is one of the most common used solar water heating system for household, hotel, hospital, project application etc. It has simple structure and working principle but is the most economical.
It is easy to be installed on the roof to get enough water flow pressure, because the compact system is non-pressurized, water flow depending on gravity water head. This system matched with vacuum tube solar collector. Water flow inside and complete a circulation on it own without given pressure, that is how the name comes from.

Specifications:

1) Thickness of bracket: 1.5mm

2) Heat-pipe vacuum tube: 58mm x 1.8m x 15pcs - 36pcs

3) Inner tank: SUS304-2B food grade stainless steel

4) Outer tank: FVDF100

5) Capacity: 150L - 360L

6) Insulating layer thickness: 50mm - 60mm

7) Inner tank thickness of: 0.4mm - 0.5mm

8) Tank diameter: 460mm

9) Pressure: 0Pa

10) Heat preservation: 72hrs

11) Hail resistance: 25mm

Key Features
1. Inner tank material: Standard stainless steel 304-2B grade, thickness up to 0.5mm.
2. Outer tank material: Galvanized Steel or stainless steel, thickness 0.31mm.
3. Heat insulation layer: 50-60mm integral foam polyurethane.
4. Frame: Galvanized steel coated anti-corrosion layer or stainless steel, it can be settled on inclined and flat roof.
5. Accessories such as screws, gasket rings and connectors are free. All installation and  operation documents are free.