US Patent 11231182 Water heater with hardness detection system

A tankless water heater including a water inlet, a water outlet, a conductivity sensor, a temperature sensor, and 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. The water heating system can further include a controller communicably coupled to the conductivity sensor and the temperature sensor, where the controller calculates an adjusted conductivity of a flow of water through the water heater.