... 2.Certificate:SRCC,CE,Solar Keymark,ISO 3.Deliver time:Within 3days water heat pump DescriptionVacuum tube58-1800mm co ... :1,The high quality vacuum tubes ansorb the solar ultraviolet ray;then heat the cold water in ... cold water sink to bottom,then heat by solar collector.so the whole system is always circulatingcontinuously.3 ... full,it will close the valve automatically solar water heat pump(CE,CCC,ISO)