Titanium immersion heaters

In modern properties, water heating now accounts for over 50% of the total heating and hot water requirement. Even in older properties where extra insulation has been fitted this will apply. This presents the installer with a variety of options with which to satisfy the water heating demand.

Alan Clark, project manager at Heatrae Sadia Ltd, discusses the issues. Further information can be found in the May 2001 edition of PHAM news.

The variations in modern water supply mean that careful thought should be given to the selection of immersion heaters, especially when replacing failed units. The standard immersion heater uses a copper sheath but nickel alloy sheathed immersion heaters are the traditional alternative for aggressive conditions. However, even nickel alloy sheathed immersion heaters have been known to fail in a relatively short time in some parts of the UK. In such conditions a titanium-sheathed unit should be considered.

Copper has traditionally been used for pipes, cylinders and immersion heaters because of its high resistance to most forms of corrosion. However, acidic water conditions in highland or moorland areas, can significantly curtail the life of copper-sheathed immersion heaters (and storage cylinders). Similarly, high levels of nitrate in the water supply can adversely affect the life of copper units.

Nickel alloy immersion heaters offer improved resistance under such conditions. There are various grades of nickel alloy element and these offer superior resistance to corrosion under the conditions described above. However, nickel alloy also has its limitations, especially in hard water areas. High levels of chlorides in the water can result in pitting and crevice corrosion, as they do in some grades of stainless steel storage cylinder. Under these conditions, nickel alloy may prove to be no more effective than copper!

Another positive factor in the design of titanium-sheathed elements is the absence of brazed or soldered joints which can themselves be a source of corrosion failure in copper and nickel alloy elements.

Inevitably the cost of titanium immersion heaters is higher than copper or nickel alloy but if the heater is used in aggressive water conditions where other immersion heaters fail, additional cost will be recouped within months. A typical 3kw titanium immersion heater costs £6.00 more than the equivalent top-grade nickel alloy unit or £14.00 more than a copper unit. The call-out and labour costs of a return visit by the plumber will be much higher than the additional cost of a titanium immersion heater, even without the added cost of a new immersion heater. Furthermore the labour involved in repeatedly draining down a cylinder, is avoided.

The reputation of a contractor who is able to solve a problem with Frequent immersion heater failure can only be enhanced. Meanwhile the contractor who replaces an immersion heater with a copper or nickel alloy unit which fails a few months later is unlikely to secure follow-on business.

Heatrae Sadia's confidence in its range of titanium-sheathed immersion heaters is underlined by the five-year unconditional guarantee. Furthermore, these units are fitted with the company's RDT reset able double thermostat as standard to offer enhanced safety in accordance with the new harmonised European standard for immersion heaters BS EN 60335-2-73.