Tankless water heater having integrated scale control module

A tankless water heater comprising:

• a source of heat;
• a scale control module (SCM) for treating supply water to generate treated water with reduce scale-forming characteristics, the scale control module including a SCM connector having a SCM inlet adapted to receive the supply water and a SCM outlet for delivering the treated water from the scale control module, and a SCM cartridge that is removably mounted to the SCM connector, the supply water being treated by the SCM cartridge to become treated water;
• a heat exchanger having a water inlet in fluid communication with the SCM outlet to receive the treated water, the heat exchanger adapted to transfer heat from the source of heat to the treated water as the treated water flows through the heat exchanger to generate heated treated water, the heat exchanger including a water outlet for delivery of the heated treated water;
• and
• a cabinet defining an interior space which encloses at least a portion of the heat exchanger,
• wherein the SCM connector is secured to a wall of the cabinet such that the SCM inlet and the SCM outlet are within the interior space and the SCM cartridge is external to the cabinet.