The Rinnai Sunmaster Evacuated 30 Tube Systems 215L is available with electric boost or continuous flow boost and is frost tolerant to temperatures as low as -12° C. The system consists of a cost-effective Vitreous Enamel ground mounted storage tank that is installed separately to the highly efficient tubes mounted on the roof. A solar control unit is what ensures water circulates between the tank and the header across the top of the tubes. Rinnai designs their innovative products with the environment in mind and with low emission technology.