Dual input water heater

A water heater system comprising:

• a tank for storing water;
• a flue assembly positioned within the tank and having an inlet end and an outlet end, the flue assembly adapted to transfer heat from flue gases within the flue assembly to water in the tank;
• a burner in fluid communication with the inlet end of the flue assembly and operable in at least a high input mode and a low input mode to deliver the flue gases to the flue assembly;
• an exhaust assembly including a fan and being in fluid communication with the outlet end of the flue assembly;
• a controller;
• and
• a sensor coupled to the controller,
• wherein the controller activates the burner in the high input mode or the low input mode based on an output reading of the sensor, and
• wherein the flue gases do not condense in the flue assembly when operating in the high input mode, and
• wherein the flue gases condense in the flue assembly when operating in the low input mode, and
• wherein operation of the fan reduces a temperature of the flue gases in the exhaust assembly to below
• a threshold temperature at least in the high input mode, the threshold temperature being a temperature rating of a construction material of the exhaust assembly.