Abstract
Failure of immersion heater elementsin a normally operating copper hot water storage tank may be caused by corrosion, or by development of an electrical defect. Corrosion failure is due to perforation of the element sheath (generally copper) or corrosion leakage of the soft solder seals between the sheath and the element boss. Electrical defects may occur owing to faulty manufacture, overheating under convection barriers such as scale deposits, or normal deterioration after long service.
In the majority of New Zealand domestic installations, element failure is of little economic significance. Frequent element failures at regular intervals occur in relatively few premises and these have particularly saline and/or scale forming water supplies. Such waters are usually of underground origin and are often not particularly aggressive to any part of the water system other than the water heater element. Corrosion failure ofan element constitutes a potential danger.
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