Water heater with hardness detection system

A tankless water heater comprising:

• a water inlet;
• a water outlet;
• a heating chamber connected to the water inlet and the water outlet, wherein the heating chamber is configured to heat a flow of water received from the water inlet and output the flow of water to the water outlet;
• a conductivity sensor configured to measure an electrical conductivity of the flow of water;
• a temperature sensor configured to measure a temperature of the flow of water;
• and
• a controller comprising processing circuitry, the controller configured to:
• output a signal to the conductivity sensor;
• receive conductivity data from the conductivity sensor and temperature data from the temperature sensor;
• calculate an adjusted conductivity value of the flow of water based on the conductivity data and the temperature data;
• monitor the adjusted conductivity value over a period of time;
• in response to determining that the adjusted conductivity value has increased over the period of time, decrease an amount of time before an automatic descaling cycle should be initiated;
• in response to determining that the amount of time before the automatic descaling cycle should be initiated has elapsed, output a control signal to initiate the automatic descaling cycle;
• and
• in response to determining that the automatic descaling cycle has been initiated and that the adjusted conductivity has leveled out over time, determining that the automatic descaling cycle has been completed.