It can all get very confusing. Sometimes. When the law steps in to reduce the risk of accidents in the home it is generally welcomed by everyone. But sometimes the details of that 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 this case, treats the various items in the bathroom differently, then the confusion can multiply.

A little clarity is called for the laws regarding the use of Mixing Valves (Mechanical or Thermostatic) may be an example of such confusion. The Bathroom Manufacturers Association (BMA), a trade association which represents almost 80 bathroom brands in the UK, has been asked to help clarify, in simple terms, what the exact position is concerning mixing valves.
What is a Mechanical Mixing Valve?

A mechanical mixing valve mixes hot and cold water so that it can be delivered at an appropriate temperature for use. The supply pressures should be balanced and there should be no other draw offs connected to the pipes supplying the fitting. The temperature of water delivered for use will change, with changes in the temperature of the hot and cold supplies and with any change in the supply pressures.

What is a Thermostatic Mixing Valve?

A thermostatic mixing valve (TMV) is an anti-scald device which blends hot and cold water to deliver that water at a preset, constant and safe temperature to the user.
The TMV may be a separate mixing valve which sits between the supply pipes and a mixer tap or hot water tap, or it may even be part of a mixer tap itself.
The TMV can be a life saver since in the UK alone there are as many as 20 deaths per year and almost 600 serious injuries from bath-time scalding. TMVs are therefore a very welcome and sometimes essential piece of bathroom equipment.

The Scottish Position

On 1st May 2006 the Scottish Building Regulations were published and they are very specific. They state that, in order to prevent scalding, the temperature of hot water discharged into any bath or bidet (in a new domestic property) should not exceed 48°C. Only baths or bidets are covered in the regulations and there is no requirement to control maximum discharge temperature to a domestic washbasin or shower or kitchen sink. This means that mechanical mixing valves can be used at those points of use.

Temperature control of water being discharged into baths and bidets can be achieved by the use of a TMV or a thermostatic ‘fitting’ and these should comply with British Standards BS EN 1111 or BS EN 1287.
Furthermore, they should ideally be tested and approved by the ‘TMV Scheme.’ A domestic TMV should be approved to TMV2 of the Scheme and should therefore have ‘BuildCert Certification.’

A commercial installation is slightly different since discharge into a shower is included in the Scottish Building Regulations. However, the temperature of hot water at the point of delivery should still not exceed 48°C.

The Position in England and Wales

English and Welsh legislation differs from that in Scotland. At the time of writing, existing English and Welsh Building Regulations for dwellings do not cover the scalding issue. There is no current legal requirement for a TMV or thermostatic fitting in a domestic property. This means that currently, mechanical or thermostatic mixing valves can be used wherever hot water is needed.
However, much work is progressing and the planned new ‘Building Regulations Approved Document G’ may soon include similar regulations to those in Scotland.

Approved Document G was recently the subject of consultation and the UK Government is due to publish the results of the consultation in April 2009. If all goes to plan the new regulations will become effective in October 2009, but there is still no guarantee that they will include any rules about hot water temperatures at the point of delivery.

Summary of the requirements in homes
Scotland
• Scottish Building Regulations currently require that the maximum permissible temperature for water discharging into a bidet or a bath in a home is 48°C. This may be achieved using a thermostatic mixing valve or fitting which conforms to the relevant British Standards and best practice is certification under the TMV Scheme.
• A mechanical mixing valve can be used in dwellings with a shower, a washbasin or with a kitchen sink.
England and Wales
• In England and Wales there is currently no requirement for maximum discharge temperatures in dwellings but the planned new building regulations (effective from October 2009) may include requirements for hot water discharged into baths.
• This means that currently mechanical and thermostatic mixing valves can be used wherever hot water is needed.

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
For more information,please visting
http://www.bossgoo.com/