Water heater

A water heater comprising:

• a cabinet having an inlet and an outlet;
• a flow path fluidically coupling the inlet and the outlet, the flow path having a plurality of upper junctions and lower junctions to direct the flow path;
• at least one flow rate sensor disposed along the flow path;
• at least one inlet temperature sensor disposed along the flow path adjacent the inlet to measure an inlet temperature;
• at least one outlet temperature sensor disposed along the flow path adjacent the outlet to measure an outlet temperature;
• at least one pair of heating elements disposed within the flow path between the inlet and outlet temperature sensors;
• plural intermediate temperature sensors configured to measure a respective intermediate temperature at a respective location along the flow path, the plural intermediate temperature sensors being disposed on each of the plurality of upper junctions, each of the plurality of lower junctions, or a combination thereof, and the plural intermediate temperature sensors are disposed between the at least one pair of heating elements;
• at least one drain port disposed at the lower junction;
• a controller configured to operate the at least one pair of heating elements to heat a fluid within the flow path to a predetermined set point temperature, the controller enabling the at least one pair of heating elements when the at least one flow rate sensor measures a flow rate greater than a predetermined activation flow rate, and disabling the at least one pair of heating elements when the at least one of flow sensor measures a flow rate less than a predetermined deactivation flow rate;
• a user interface configured to allow the user to adjust the predetermined activation flow rate and the predetermined deactivation flow rate, the user interface including a display having a plurality of screens to display information to a user, the plurality of screens comprising:
• a first screen of the plurality of screens displaying at least one of a setpoint temperature, the flow rate, and the outlet temperature;
• a second screen of the plurality of screens displaying at least one of the inlet temperature, each intermediate temperature, and the outlet temperature;
• and
• a third screen of the plurality of screens configured to allow a user to toggle between an operation mode and a test mode;
• and
• a communication interface external of the cabinet and in communication with the controller via of a Modbus communication protocol.