Definition
Enamel coating is a glass-like layer fused onto the inside of a carbon-steel hot water tank at around 850 °C to protect the steel from corrosion by drinking water. Standards such as DIN 4753-3 define its quality, and because microscopic pores are unavoidable, enamel tanks are always fitted with a magnesium or impressed-current anode. Enamel is the cost-effective standard for DHW cylinders and inner tanks of combi units.