... 4,Anti-freezing -40 degree Newest heat pipe split pressurized solar water heater(CE,SABS,Keymark,EN12976 ... winter, much more than that of the all-glass tube 2) The flow passage is inner closed and pressurized ... is inserted into a closed cannula welded into the copper flow passage, collector works well even withdrawal ... problems 2012 top sale heat pipe split pressurized solar water heater(CE,SABS,Keymark,EN12976 ...