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two effective solutions to this problem: tempering valves and thermostatic mixing valves (TMVs), both essential factors in safe hot water systems.

Thermostatic mixing valves – a certified solution

TMVs use an internal thermostat to automatically achieve and maintain safe water temperatures, typically around 48°C. In the event of hot or cold water failure, they quickly shut down. There are two TMV schemes available. TMV2 which is designed for domestic, commercial and public buildings and the TMV3 which must be used in hospitals, care homes and other healthcare environments. Both comply with key British Standards, but TMV3s also meet other requirements, including the NHS D08 regulatory standard. In 2012 TMVs became a legal requirement in all new domestic and

commercial builds as well as in any properties undergoing a change of use (Part G building regulations). There is a wide range of TMVs available to meet the requirements of different applications.

For example, RWC’s Reliance Valves has a suite of TMV2 and TMV3

compliant valves including the Ausimix Compact or Ausimix Telescopic TMV’s and Heatguard Dual TMV. Many have additional features, ranging from anti- tamper caps, check valves and strainers through to isolators and test ports, providing an appropriate solution for every challenge.

TMV installation and maintenance

There are specific installation requirements for each application. For instance, while public toilets or showers can use a single TMV to serve multiple outlets, in hospitals it is necessary to install a separate valve for every water outlet identified in the risk assessment. Equally, in domestic properties, they should always be fitted directly under the bath and aren’t suitably designed to be installed directly to a cylinder. In all cases, it’s vital to check product data sheets to ensure the right flow

rates for the application, and to connect the hot and cold water pipes the right way around. This might sound obvious, but mistakes do happen, and the consequences can be very serious. In safety, every detail should be checked and double-checked for peace of mind. Equally, wherever possible, TMVs should be installed into easily accessible spaces to simplify maintenance and servicing. Here, RWC’s Ausimix Compact Telescopic TMV is a game-changer. WRAS approved for TMV2 and TMV3 applications, it’s a great solution when space is hard to come by. With adjustable union connectors, its application is extremely flexible, especially in retro-fit installations. Able to deliver 35 l/min at 2.5 bar pressure and a unique temperature adjustment tool incorporated into the cap, the Ausimix Compact Telescopic is also Building Regulation Part G and D08 compliant.

All TMVs must be regularly serviced and tested in order to validate

certification. In the case of TMV2s in commercial applications, this should be annually. For TMV3 valves it’s more rigorous, including detailed periodic checks six to eight weeks after installation. These tests include a temperature calibration check, hot spike and stability testing, as well as ensuring the fail- safe shut down response time is as it should be. It’s best practice to keep a detailed checklist for every installed TMV, including temperature settings, and giving copies to the building owner/ landlord for peace of mind. Another valuable anti-scalding solution comes in the form of tempering valves.

Tempering valves – effective and easy to install

Tempering valves provide a reliable and easy to install back-up for pressurised cylinders. Fitting easily onto the hot water outlet and cold mains water, they effectively regulate the outlet temperature for an entire property. The valve is pre-set at 55°C, significantly reducing the risk of scalding while maintaining protection against legionella. Any excessively hot water leaving the cylinder is mixed with cold to ensure a safe and stable temperature. Tempering valves can be set at higher temperatures than TMVs and provide

protection from temperature fluctuations at outlets where TMVs are not installed. Though not legally required, tempering valves add an extra safety layer, helping protect homeowners from the risks of scalding as well as protecting housebuilders from potential litigation. By recommending them, installers are doing the right thing and demonstrating commitment to their customers’ wellbeing.

Tempering valves - installation and maintenance

Installation of tempering valves is quick and easy, especially with devices such as Heatguard from Reliance Valves. To ensure even easier installation, this comes complete with 22mm compression connections, while a tamper- proof cap keeps the valve safe in openly accessible places. The functioning of tempering valves is further enhanced with strainers in order to catch debris. These need to be serviced and cleaned if there’s ever a drop in temperature.

Supporting the drive to safety

While scalding will always be a risk in today’s high-pressure water systems, there are very effective ways to prevent its occurrence, and it’s the responsibility of the industry to provide best advice, and to do the right thing in protecting water systems and people.

August 2021


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