Cause: In untreated heating systems, corrosion debris accumulates in the boiler and, in hard water areas limescale will form. The insulating effect of these deposits reduces heat transfer to the circulating water. 3mm of limescale deposit on the heat exchanger will add 18% to your heating fuel bill. Cause: Black Oxide sludge forms continuously in all unprotected central heating systems as a result of corrosion. It will also harden into scale on the hottest surfaces of a system.
