Rheem. SRCC-labeled Solaraide passive solar water heating systems operate without pumps or controllers. A closed-loop, indirect heat exchange design wraps completely around the unit’s roof-mounted thermo-siphon exchange tank for optimum efficiency. Single or double flat-plate collectors in 47- or 80-gallon capacity include multiflow risers that transfer heat rapidly and provide heated potable water directly to the home’s existing or backup water heater. The company also makes SolPak active solar thermal systems and storage tanks. 800.621.5622.