... solar water heater 1.For 5years warranty 2.CE,CCC,ISO,approved 3.OEM is welcomed 4.Sample offer (OEM)Non pressure solar water ... heaterWorking Principle: Parameter:1. Water tank inner shell: 0.4 ... -2B (food grade stainless steel).2. Water tank outer shell: 0.4mm colored steel ... or Aluminium alloy, or stainless steel.4. Water tank heat insulation layer: 50~60 mm ...