Scalding Water from the Tap? Thermostatic Mixing Valve can Help

It has happened to all of us, you turn on the hot water tap just to get a scalding flow of very hot water from the tap. The pain and sensitive skin that follows is the lowest level of injuries that are caused every year in the UK from overheated water, which in extreme cases leads to fatal injuries.

Last autumn the Health and Safety Executive issued new guidelines to care homes instructing them to install temper proof thermostatic mixing valves (TMV). This new set of guidelines came in the wake of another tragic fatal injury from scalding water.

The Scottish Building Standard already requires all new property developments and major refurbishments to install thermostatic mixing valves. Although not compulsory in the rest of the UK at the moment the Building Regulations in the UK are working towards adding it in a future update.

To reduce the risk of Legionella, it is required to keep hot water (for example within a hot water tank) at temperatures of between 60 and 65 degrees Celsius. At these temperatures it is believed that the Legionella virus does not survive. Nevertheless, water coming out of the tap at that temperature is too hot and should be mixed with colder water first.

TMVs are particularly important in public buildings or properties with communal water heating systems. Hot water regulations in the UK require water to be kept at high temperature throughout the system (up to the point of delivery) to reduce the risk of Legionalla.

Young children and old people are the most at risk from scalding water injuries. Hundreds of young children are admitted every year to hospitals in the UK with severe burns from hot baths. Their extra sensitive skin gets burned easily and they may be left with permanent scars. Similarly, older people may not feel the heat of the water fast enough or react fast enough to turn off the hot water tap, leading to severe burns. The same is true for mentally or physically impaired people that have slow response time and slow reactions to pain.

There are broadly two types of thermostatic mixing valves that are suitable for installation and certified:

TMV2 kits are mostly used for domestic installations. However, they are also suitable for most other properties. It is required to undertake a full risk assessment to review if there are disabled or vulnerable people on the premises.

TMV3 valves are designed for higher performance to offer the maximum safety levels. TMV3 valves are required for all healthcare premises, or premises with disabled or vulnerable people (such as mentally or physically handicapped people).

Most manufacturers of thermostatic mixing valves recommend qualified plumbers for the installations of their kits. For a qualified plumber, the kits are easy to install between the hot and the cold pipes to ensure effective mixing action. Most kits are designed for a simple installation under the bath or under the sink and include several important components. At typical kit includes tailpieces with isolation, a strainer and test points. To handle installation in limited spaces, there are kits with a flexible connector and isolating filter valve.

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