... 2. 0.68~0.73 premium conversion Vacuum tube solar collectors -- Keymark/EN-12975,SRCC,ISO,CE,CCC Feature: ... Working principle1) When the discrepant temperature of the solar collector and water tank reaches the set value, the ... heating 8) Workable at anytime and enjoyable HEAT PIPE SOLAR COLLECTOR TECHNICAL DATAMANIFOLDManifold casing materialAnodized aluminum alloyManifold header pipeTU2 ...