A system for descaling a water heating unit, said system comprising (so that the abstract is directed to the presently allowed apparatus, rather than a method): a pump; a descaling solution source; a plurality of valves; a programmable control module operatively coupled to said pump, said descaling solution source, and said valves, said programmable control module adapted to selectively receive a user-defined descaling operation start date and time, monitor for the advent of a descaling operation start date and time, and upon the advent of the descaling operation start date and time, automatically shut off via at least one valve, a supply of heated water, and automatically activate said pump; said pump adapted to automatically pump stored descaling solution, and further adapted to automatically rinse a water heating unit; and said programmable control module further adapted to cause said valves to discharge solution from said water heating unit, restore a supply of heated water, and return said water heating unit to normal operation mode.