Water heaters with enamelled tank

Enamel

— the enamel is strong and chemically resistant but sensitive to temperature changes — microcracks appear in it, which can cause corrosion of the main material of the tank. Therefore, water in such tanks is not recommended to be heated above 60 °C. At the same time, this does not apply to models with titanium enamel — they tolerate temperature changes without problems (however, they cost accordingly).