Solar water heater. Solar heaters, solar energy water heater, Solar Heaters Model: SPECIFICATION: 1. Material of Inner Tank: SUS304-2B Stainless Steel, thickness: 0.4mm. 2. Material of Outer Tank: ... . For the original features of the copper coil, the water temperature of the outlet is close to the water temperature of the water tank(≤ 3C), so the high pressure of the cold water into the copper ...