... can be from 1000L-30000L Split Pressure Solar Water Heater:Vacuum tubes assimilate the advance 12 layers ... strong heating ability, Certificate, CE, CCC, ISO 9001, Solar Keymark.Features:1) Highest efficiency2) Furnished in good style ... heating element is optionalSpecifications1) Vacuum tube counts 15,16,18,20,22, 24,26,28,302) Angle 38/ ... ) Isolation: 50/55 polyurethane Split Pressure Solar Water Heater