The TMV Scheme - thermostatic blending valves for safety against scalding

A TMV (which stands for Thermostatic Mixing Valve) is a control that can (or in some cases must) be installed to the incoming hot water pipe feeding a bath or basin to avoid the risk of scalding for the user.

How does a TMV work?

A TMV can be adjusted to a set temperature. Should incoming water arrive at the valve any hotter than required the valve automatically blends cold water into the feed to reduce the output to the set temperature.

The TMV scheme is a government initiative and will eventually become law. It is wise to fit TMVs to all domestic outlets, especially where the very young or the elderly will potentially put themselves in harms way. Every year children die an agonising death by falling into baths during filling where the water temperature is dangerously high. Elderly people with reduced or delayed sensation are prone to scalding because they simply can't react quick enough to realise water is too hot.

Walk in baths are becoming very popular with the elderly and persons who suffer from limited mobility. Just imaging the horrific nature of the injuries one would risk if you climb into the bath, close the door, then open a tap to be showered with scalding hot water! A Walk in bath that is not protected by a TMV is rather like playing Russian Roulette. Don't ever let anybody tell you it will be OK - it won't! Cutting corners to save a few pounds is utter stupidity. Just think, you install an expensive walk in bath to make life more comfortable then you risk burning your feet!! Questionable logic at best.

So what is the difference and why do some cost more than others?

The TMV Scheme awards a number based on performance. Basic control is offered by a TMV whereas a high level of control is opffered by a TMV3.

	Type 1	mechanical mixing valves with maximum temperature stop (including single lever taps).
	Type 2	a thermostatic mixing valve of lesser performance to D 08 which conform to EN 1111’s and 1287 (originally BS 1415 Part 2).  These can have a maximum temperature stop which is excluded by the requirements of D 08.
	Type 3	a thermostatic mixing valve with enhanced thermal performance complying with NHS Estates requirements.

There are two factors to consider when choosing a blending valve.

1. The performance level 1, 2 or 3.

2. The flow rate through the valve when operating.

The flow rate is a particularly important factor when choosing a valve for example to serve a walk in bath. The flow rate is how fast the valve can deliver regulated water. Consider, if you were sitting in a bath waiting for it to fill you would be glad for it to do so as quickly as possible. It is therefore important to choose a TMV3 valve with a high potential flow rate. This is where you will pay more for one valve over another. As a rule of thumb, the dearer the valve the better the control function and the higher the potential flow rate or throughput of water.

TMV2 and TMV3 Valves are an essential safety feature to ensure water cannot reach taps at an unsafe temperature. By incorporating a Thermostatic Blending Valve you can prevent  accidental scalding and injury.

TMVs are easily easily installed and represent a sound investment if you truly care about saftey.

For further information on the TMV Scheme and the classifications please click here

New Scottish Building Regulations as of 1st May 2006

Saracen