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The law concerning Thermostatic Mixing Valves
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When the law steps in to reduce the risk of accidents in the home it is generally welcomed. But sometimes the details of the law can be confusing. Sometimes the law in Scotland is different from that in England and Wales, and this adds to the confusion. And when the law, as in the case of the use of thermostatic mixing valves (TMVs), treats the various items in the bathroom differently, then the confusion can multiply further.
For the installer it can be a minefield but here the Bathroom Manufacturers Association offers some clarity.
Firstly, there are two definitions: A simple mechanical mixing valve combines hot and cold water for delivery at a temperature set by the user. But that water temperature will change if the temperature of the hot and cold supply varies and if the supply pressure changes. A thermostatic mixing valve (TMV), however, blends the hot and cold water to deliver it at a preset, constant and safe temperature. The TMV may be a separate mixing valve sitting between the supply pipes and the tap, or it may be part of the tap itself. The TMV is an anti-scald device and can be a life saver.
In Scotland the latest Building Regulations are very specific. They state that, to prevent scalding, the temperature of hot water discharged into any bath or bidet (in a new property) should not exceed 48°C. In this case a TMV would be used. But there is no requirement to control the maximum discharge temperature to a domestic washbasin or shower so in these cases it is still permissible to install a mechanical mixer.
In England and Wales the legislation is different since the existing Building Regulations do not cover the scalding issue. There is no legal requirement for a TMV in an English or Welsh domestic property. So, currently, mechanical or TMVs can be used.
However the new ‘Building Regulations Approved Document G’ – which are due to become effective in October 2009 - may (or may not) include similar regulations to those in Scotland.
The BMA is constantly tracking all technical aspects of the bathroom industry and in its role as ‘The Voice of the Bathroom Industry’ keeps its membership fully up-to-date with the very latest developments. Information is published regularly on its website at www.bathroom-association.org.
Further Information
For further information please email info@bathroom-association.org.uk or
telephone 01782 747123 and visit www.bathroom-association.org

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