How installers can protect people and the NHS with TMVs

thermostatic mixing valve

The coronavirus outbreak, otherwise known as the COVID-19 pandemic, has really brought some unprecedented times with it. Healthcare systems around the world are under strain, none more so than our own NHS in the UK.

At the time of writing, instructions from the government are clear – stay at home and save lives by not overwhelming the NHS. However, even at home, we could be prone to health hazards and accidents. One area where we must be particularly vigilant is the use of hot water and how it can be effectively controlled to prevent unexpected trips to A&E.

In this blog, we’ll discuss why thermostatic mixing valves (TMVs) are crucial for protecting users of hot water systems from getting scalded or catching Legionnaires disease, both in the home and in other commercial, public and healthcare buildings.

We’ll also discuss why public-use buildings which have not been in operation since the lockdown should take additional measures to treat their water systems upon re-opening.

Why are TMVs so important?

TMVs are crucial because they allow hot water to be stored at a constant high temperature to prevent Legionella bacteria from breeding in the system, while ensuring safe water temperature from outlet to prevent scalding injuries.

The key to avoiding Legionnaires’ disease is to kill the bacteria in water supplies themselves. Water needs to be stored above 60°C in domestic and above 70°C in commercial, healthcare and public buildings to kill Legionella. However, these temperatures are hot enough to cause scalding.

To resolve these concerns TMVs are installed before the water outlet. They allow the hot water system to run at a higher disinfection temperature, which can be blended with cold water at the point of use to achieve a pre-set safe temperature from outlet. Alongside this, TMVs are also responsible for ensuring a safe outlet temperature even when water pressure fluctuates due to the simultaneous use of other appliances.

To protect end-users from the risks associated with the use of hot water, in 2012, TMVs were made a legal requirement for all commercial and domestic new builds or properties undergoing a ‘change of use’. This was done to overcome the challenge of balancing water at a high temperature to prevent Legionnaires disease whilst avoiding scalding.

How does a TMV work?

TMVs use an internal thermostat that automatically blends hot and cold water to achieve safe water temperature from outlet. All TMVs from Reliance Valves feature a rapid failsafe mechanism to shut off the valve for stopping the water supply to outlet, in case either hot or cold supplies are cut off/interrupted.

Heatguard push fit

Choosing the right TMV

There are several TMVs to choose from – but the key to a successful installation is understanding the application first. This is because domestic, commercial and public buildings have different requirements to healthcare buildings.

TMVs for domestic, commercial and public buildings

Domestic, commercial and public buildings must use TMV2 certified valves – formerly known as the BuildCert scheme. Under this scheme TMVs must maintain a safe and stable temperature of under 48°C at all times and quickly shut off in the event of hot or cold-water failure. TMV2 certified valves also need to be annually tested in commercial applications. The certification is invalid if this test is not conducted every year.

All of RWC’s TMV2 certified valves, such as the Easifit® and Ausimix® come complete with either 2-in-1 fittings that include check valves and strainers, or 4-in-1 fittings which in addition incorporate isolators and test ports. Isolators allow the water supply to be shut off for that TMV only, helping streamline the periodic testing and servicing process. The parts of the valve that need testing and servicing can be easily demounted, and then re-installed once the valve has been checked and cleaned, allowing the rest of the system to work as desired without interruption.

NHS staff in operating room

TMVs for healthcare buildings

With the coronavirus reaching its peak, it is possible that we’ll need more makeshift hospitals to be built in record-breaking times, such as the Nightingale Hospital that was transformed in under a fortnight from the old ExCeL conference centre in London.

With these types of projects, it’s vital that the plumbing and heating systems are carefully selected, especially with so many vulnerable people landing in intensive care.

This is why healthcare buildings have more stringent regulations and must use TMV3 valves. TMV3 valves follow more rigorous testing processes with periodic checks six to eight weeks after installation.

These checks include a thermal element endurance, hot spike and stability test, and a response on temperature adjustment and fail stop valve check. If the valve isn’t checked within the required timeframe its liable to be marked as non-compliant and may no longer be suitable for use.

RWC’s range of TMV3 compliant valves include the Easifit®, Ausimix® and the Heatguard® Dual. An added feature on these valves are the anti-tamper caps, which prevent any unwanted tampering as these TMVs are sometimes installed in places that can easily be accessed by the public.


Legionella bacteria build-up during lockdown

With many public buildings and businesses shut during lockdown, stagnation within water systems is something that could be a real danger to users, especially once normal activities are resumed. This stagnation could potentially lead to the growth and multiplication of Legionella bacteria in the water supplies.

It is therefore imperative that these water systems are carefully cleaned and flushed once lockdown is lifted. If not, we could potentially see a large increase in cases of Legionnaires’ disease – an extremely harmful form of pneumonia.

Safeguarding people with TMVs in critical times

There’s no doubt that these are critical, extraordinary times. We must do everything we can to protect our people and the NHS and put less strain on our amazing frontline healthcare workers.

Whether you’re a domestic installer or contractor, or a specifier for commercial and healthcare buildings, it’s vital that you understand and use TMVs in the right way. At RWC, we can provide you technical support on how to use these valves and help in sourcing the products you need for the installation. We’re with you all the way.

We will be following up this blog with advice on how to treat water systems once lockdown is lifted, so please stay tuned. In the meantime, find out more about our range of TMVs here.

Easifit TMV2/3

Compact mixing valve that blends hot and cold water thermostatically to ensure a safe outlet temperature.

Lee Halstead Headshot

Lee Halstead

Technical Sales Engineer - JG Speedfit/Reliance/SharkBite & JG Underfloor

About the author

As a seasoned professional in plumbing and heating, having earned City and Guilds Plumbing Craft and Advanced Craft certifications in 1991, I have dedicated myself to mastering the craft.

For over two decades, I operated as a self-employed plumbing and heating engineer, serving both residential and new build sectors.

In 2015, I transitioned into the role of a Technical Sales Engineer with RWC. In this capacity, I have leveraged my extensive field experience and technical knowledge to provide invaluable support and build strong relationships with customers. As a spokesperson for RWC, I am thrilled to share my expertise and promote the cutting-edge products and services we offer in the plumbing and heating industry.