solar water heater: 1.SRCC,Keymark,CSA,UL,SABS,CE,ISO approved 2.High ... of this heat transfer process. 1. The perfect combination of vacuum tube and heat pipe makes higher heat efficiency: heat pipes quick ... even in -40degree centigrade. As no water flows in vacuum tube, it can avoid frost cracking or scaling which influence heat ... solar water heater which approved by CSA,Solar keymark,SRCC,En12975