... system and 15 years for vacuum tube.Non-pressurized solar energy1.solar water heater with CE,3C,ISO9001,CNAL certificate;2.special good ... the original equipment;7.long life span and no extra cost after installation.MaterialInner tank: stainless steel SUS304/2B, 0 ... CCC, CE, ISO,CNAL6.Long life span and no extra cost after installation7. Easy opearationSpecification:Inner tank: stainless steel SUS304/2B ...