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Thermostatic Mixing Valves for the Home
To comply with new Scottish building regulations as of 1st May 2006 any domestic property being built new, or undergoing major alterations which include the bathroom must incorporate control of the temperature of the hot water supply to the bath to a maximum of 48C. Since it also a requirement that the hot water heater be run at 60°C and that the hot water system should circulate at no less than 55°C, it is clear that some form of extra control will be required to ensure that the maximum allowable bath fill temperature is not exceeded. An ideal and simple solution is to fit a thermostatic mixing valve at the point of use.
Why?
It has been recognised for some time throughout the UK that the frequent deaths and permanent severely disfiguring injuries caused to people by scalding is a wholly preventable problem. Every year over 500 people are admitted to hospital with burns from scalding so severe that they require admission for long periods and painful operations. Many of these victims are children or the elderly who have fallen into scalding bathwater and lack the ability to get out quickly. Since 1997, when the NHS Estates published the model engineering specification DO8 for thermostatic mixing valves, it has been a requirement that any facility where people were considered to be at a high risk of injury from scalding should have a thermostatic mixing valve fitted. Over the years this ethos has developed to the point where virtually any public building, school, leisure centre, prison etc will use these valves as standard to protect the public from being scalded. In England and Wales the government announced a review of part G of the building regulations would include a consultation on the fitting of TMVs in the domestic environment; this is currently underway but is unlikely to conclude before 2007. Scotland has gone one better and has decided to bring in this requirement ahead of the rest of the UK and include it in the Scottish Building Regulations from 1 May 2006.
For further information on support and advice regarding scalding and burns, visit the Children's Fire and Burns Trust website.
What is a Thermostatic Mixing Valve?
The definition is a relatively simple one: it is a valve with a hot and cold inlet and a mixed water outlet. Hot and cold water supplies enter the valve, mix in the mixing chamber, and then the blended water leaves via the outlet to a terminal fitting.
The valve incorporates a temperature sensitive element that responds to changes in the inlet conditions to make sure that the outlet temperature is always stable. The valve must also be fail-safe: that is if the cold supply fails the valve must shut down and not allow full temperature hot water to be discharged.
How to Comply
Along with the regulation, guidance will be published on how to comply with the regulation. Within this guidance one simple method of compliance will be to use a thermostatic mixing valve which meets BSEN 1111 or BSEN 1287 to limit the temperature at the bath taps to 48°C. BSEN 1111 is the European standard for thermostatic mixing valves for high pressure applications (1-6 bar) and BSEN 1287 is for low pressures (0.2 – 1 bar); but how will anyone know if the valve they are using complies? The answer lies in a Buildcert scheme run by WRAS called the TMV2 scheme. This is a third party performance checking regime which tests products to the aforementioned standards and ensures their suitability for the UK market under the water regulations.
 Look for the TMV2 mark: it is the guarantee that the product meets the required level of performance.
Reliance has 3 valves in its thermostatic mixing valve range that meet the requirements of the TMV2 Scheme:
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Heatguard
TMV2 |
Heatguard LS2 |
Heatguard
BF2-2 |
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Market leading TMV2 approved TMV.
Click here for further information and specification sheet |
Suitable for general purpose uses.
Click here for further information and specification sheet
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Suitable for high flow bathfill applications
Click here for further information and specification sheet |
For further information on any of Reliance's products, email sales@rwc.co.uk
or call 01386 712400, fax 01386 47028 or visit www.rwc.co.uk
February 2006
Copyright: Reliance Water Controls 2006
Heatguard is a registrated trademark of Reliance Water Controls.
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How to save water and energy by utilising timeflow controls
 Although timeflow controls, or push button controls as they are sometimes called, have been with us for some time, the practical value that they can offer to the contractor, specifier and end user are still not fully understood, in some cases.
It has become normal practice in certain applications, specifically in the commercial sector - places like schools, motorway services, and leisure centres, for system designers/specifiers automatically to specify timeflow controls, and rightly so; but what are the reasons for this? Do we understand what attributes separate a good timeflow product from a bad one? How much water do they really save?
These are the questions, among others, that we seek to answer below.
Reliability is the Key
Believe it or not, even now at the dawn of the “Green” era there are a lot of people in the plumbing industry who think that timeflow taps and showers are a waste of time (excuse the pun) to fit. Firstly, they are generally more expensive than ordinary taps so the belief is that any water savings are cancelled out. Secondly, perception is that they no longer work properly after 3 months: that either you have to race to get your hand under the tap and wet it before the water shuts off or, far worse, they stick open and run all night until an engineer can come out to replace the thing.
In response to such comments we would say: that was true maybe twenty years ago, but now technology has moved on; newer and better products are being built all the time and although there are still some rogue elements selling very cheap, inferior quality products into the marketplace, there are also very good products. The question is: how do you tell the difference? There are two important things to look for. First: does the product conform to European Standard BS EN 816? Modern timeflow controls built to meet this standard are among the most reliable products to be found in the commercial washroom.
Second: does it have WRAS approval to ensure that the valve construction and the materials used in it comply with the UK water regulations? If the answer to both questions is “yes”, then you are likely to have a very good, tried and tested product that will last and do its job for a long time to come.
It is also very important that, when designing the timeflow product, the manufacturer takes into account the possible problems from scale and system contamination. These two problems are the most common factors for causing timeflow valves to malfunction. Most examples of this type of product work by allowing water pressure to equalise slowly across a diaphragm and the rate of equalisation determines the length of time the valve runs for. Typically this means that a hole of a specific size is made in the diaphragm to allow the equalisation; if this hole is blocked in any way, the time that the valve will run for can increase dramatically, defeating the reason for fitting it in the first place. If the hole is somehow enlarged or damaged during a repair or in manufacture then the run time will decrease, sometimes to virtually nothing. Because this area of the manufacturing process is so critical, the Reliance Auteau® range has a patented system which uses a vertical groove in the diaphragm housing and allows the water to equalise around the side of the diaphragm instead of through it. This system also ensures that no grit is deposited in the groove, because each time the tap or shower is used the diaphragm runs the full length of the groove, keeping it clear of debris or scale. This feature provides unrivalled reliability and longevity.
Real Savings
 Water is a precious resource and in the coming years we will find ourselves increasingly regulated over the amount of water we have available for our day-to-day needs. Every litre that can be saved becomes significant, and every tap that can be turned off when it doesn’t need to be running can help to save thousands of cubic metres of water per day.
So where do timeflow valves fit in? How much water can they actually save? Consider the following scenario. If we estimate that an average person takes approximately 45 seconds to wash their hands adequately, including the time to turn the tap on, soap up and scrub their hands and to rinse them off, and that during this process the vast majority of people will not turn the tap off in between the initial wetting and the rinsing off, this means that all the water running down the drain in between those two actions is wasted. If a conventional tap is being used without flow regulation, at least 7 litres of water (and possibly even more at higher pressures) will have been used for this simple everyday act.
If we look at the same procedure using a timeflow tap with a set shut off time after 15 seconds and a 6 l/min flow regulator (standard with Reliance products) the user will turn on the tap, have sufficient time to wet their hands before the tap shuts off automatically, they will then soap and scrub and then turn the tap back on for a further 15 seconds to rinse off. Total water usage is approximately 3 litres, giving the water saving over a standard tap of 4 litres. This is an example for just one use of a single tap: imagine how much water could be saved if all of the hundreds of thousands of hand washes were controlled in the same way.
Complete Packages from Reliance
All of the timeflow products in the Reliance Auteau range are tried and tested in one of the most demanding and unforgiving of environments: the UK commercial washroom. All products conform to EN816 and have WRAS approval. The product range is constantly being added to and upgraded.
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Auteau Basin Taps: lever and push button
For further information, click here
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Auteau Bib Taps: push button and lever.
For further information, click here. |
In addition to the standard push button timeflow taps, Reliance also offers versions with levers for the disabled, knee operated types for surgeries or food processing industries, bib taps for wall mounting applications, and most recently single handle timeflow mixer taps.
For showering, Reliance has three standard versions to cover all applications: an exposed shower control, a concealed shower control for solid wall or panel installations and a cross wall version for installation through a block wall where the supplies are in a void behind.
Recently launched products include an exposed and concealed timeflow mixer shower and a low profile shower panel.
 To complement the showering range of products, Reliance also market the patented scale proof Tonic-Jet showerheads, with different versions to suit various applications. An exposed head and riser kit, a solid wall version and a cross wall version are all available. In addition, traditional spray-type riser sets and concealed heads can be supplied.
As well as developing timeflow technology, the Reliance group are specialists and world leaders in thermostatic mixing valves which are a perfect complementary product for the Auteau controls. Group mixing valves from the Planar range are available to suit systems with anything from one to 16 outlets.
For further information on any of Reliance's products, email sales@rwc.co.uk
or call 01386 712400, fax 01386 47028 or visit www.rwc.co.uk.
February 2006
Copyright: Reliance Water Controls 2006
Auteau, Tonic-Jet and Planar are registrated trademarks of Reliance Water Controls.
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Training the Trainers
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Reliance has recently hosted training sessions for Heads of Plumbing & Lecturers from various Colleges across the UK
The purpose of the sessions was to bring together the Colleges and Reliance to relate manufacturing & products. Also to simplify the understanding process and help tutors best explain products and how they relate to building standards to students.
As well as an overview presentation on Thermostatic Mixing Valves, a practical laboratory demonstration was given explaining the working parameters of a typical RWC thermostatic mixing valve.
Additional training & product overviews our now being planned, if any college lecturers or consulting engineers wish to attend please email robh@rwc.co.uk
Photo showing lecturers from left to right: Jim Branney(Grimsby College), Ned Kelly, Andy Parlour( Somerset College), Brian Orton & Tony May (Coventry College) |
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