Following recent reports of several cases of Legionnaires’ disease in Glasgow, leading manufacturer of heating controls and water products, Honeywell, is highlighting the benefits of using Thermostatic Mixing Valves (TMVs) to combat this problem.

Legionella bacteria is present in many water systems and grows in water temperatures between 20 and 45ºC, but is killed by temperatures above 60 ºC.  If exposed to legionella bacteria, humans can develop Legionnaires’ disease, a severe form of pneumonia that can be have serious effects on health and, in extreme cases, can be fatal.

However, using water at these temperatures for hand washing, showers and bathing can pose a threat – as water temperatures increase above 50 ºC, the duration of exposure needed to suffer third degree burns decreases rapidly.

Matthew Watson from Honeywell explains: “To remove legionella bacteria, water has to be stored at 60 ºC or higher.  However, it is not as simple as this, as water delivered to a tap or shower at this temperature could result in scalding.

Therefore, the most effective way to prevent both legionella and scalding is to utilise a TMV.  This technology allows water to be stored and distributed at a high temperature to kill the bacteria, but blends it with cold water before it reaches the tap.  This therefore provides water at an appropriate temperature to use, but still reduces the risk of the spread of bacteria.”

TMVs are fitted at, or very closely to, hot water outlets to offer the best results.  Part G of the Building Regulations requires the technology to be fitted as standard on baths in new homes, but there is no regulation for existing homes.

Watson continues: “Even without an official regulation, the benefits of TMVs are easy to see.  Those working in the plumbing and hot water industries should look for opportunities to utilise TMVs, offering dual benefits to the end user.”

Honeywell offers a wide range of water products, including TMVs TM200VP and TM300, which are both WRAS and Buildcert TMV Scheme approved.