The Rinnai Evacuated Sunmaster Evacuated 25 Tube Systems 215L consists of a ground mounted storage tank that is installed separately to the tubes mounted on the roof. There is no need to reinforce your roof for the tubes and they provide a minimal impact on the aesthetics of your roofline. A solar control unit ensures water circulates between the tank and the header across the top of the tubes. It is available with electric boost or continuous flow boost and is frost tolerant for temperatures as low as -12° C.