. The built-in flow switch prevents operation when there is no water flow and allows operation at flow rates between 15GPM and 80GPM. The stainless steel tank is designed to optimize heat transfer by directing the water flow over the incoloy elements efficiently. 5.5KW 9KW 11KW 15KW 18KW 24KW . Voltage:240V . Phase:Single - Three . STANDARD FEATURES: Incoloy heating elements Digital thermostat Manual reset high temp limit Flow switch Heavy duty contactors . Element “on” light 1-1/2 x 2″ union connections for PVC pipe . UL Listed for indoor/outdoor installation