... absorb solar energy,and heats the water inside the tube,hot water rises,cold water flows down). It ... inner tank. The hot water rises from the tube into the tank, and heats the copper coil ... with a copper coil inside),the three-high vacuum tube,bracketoptional parts:A controller----show water level, temparature for ... and coated with ALN/ALN-SS/CU ,The tube we use can ensure more powerful absorbing power, ...