... value, the circulation system will start work. It will transmit the solar energy from solar collector to the tank.solar water heater features:a ... tube: new trivalent element heat tube, borrosilicate glass 3.37) Solar working station8) With heat pipe: anti-freezing > -35 degrees centigrade9 ... ,Vacuum Degree,P<=5*10-4,Service Life,10 years Mounting FrameAluminum Alloy,Thickness,1.8 mm, not have back-leg ...