Annual descaling is critical to keeping a tankless water heater operating efficiently and reliably. Over time, minerals in the water build up inside the heat exchanger, acting like insulation that forces the unit to work harder to heat water. If left unchecked, this scale can cause temperature fluctuations, error codes, higher energy bills, and even premature heat-exchanger failure. Flushing and descaling the unit once a year removes these deposits, restores proper heat transfer, protects manufa