Thermostatic Mixing Valves (TMV’s)


Hot water temperatures that do not cause scalding are ideal for legionella bacteria to grow in a water system.

However, hot water temperatures which will kill legionella bacteria will cause scalding, particularly in “high risk” people such as children and the elderly – What to do?

Hot bath water is responsible for the highest number of fatal and severe scalds injuries in the home. Every year around 20 people die as a result of scalds caused by hot bath water and a further 570 suffer serious scald injuries.


Young children and older people are most at risk from bath water scalds because their skin is thinner and therefore less tolerant to higher water temperatures than that of other age groups. As a result, they sustain scalds more quickly, at lower water temperatures and often with a greater depth of burn.

Where scalding risks have been identified, TMV’s are an excellent preventative measure to ensure your hot water arrives at a safe temperature when the end user turns on the hot tap.



TMV’s are not however a ‘fit and forget’ device and it is important that these are regularly maintained.  As a minimum, TMV’s  should be tested annually against the original performance results using the following performance checks:

  • Measure the mixed water temperature.
  • Carry out the cold failsafe shut-off test by isolating the cold water supply to the TMV.

If there is no significant change to the set outlet temperature (2°C or less change from the original settings) and the failsafe shut-off is functioning, the valve is working correctly and no further service work is required.

If the outlet water temperature has drifted from its set point by more than 2°C or if the failsafe function does not work, a full service and recommissioning of the valve is required; see the manufacturer’s instructions on servicing the TMV.

You may feel comfortable doing this yourself.  But if not, give us a call and we can do it for you as part of our comprehensive water management services.

Need some advice on TMV’s for your premises? 

If you are looking for the peace of mind that these safety critical devices are working properly, then call us NOW on 01789 270710 and we can discuss your exact requirements.

Alternatively, click the big button, leave us a message and we will get back to you asap.

Contact Us

What’s more there’s no obligation. So contact us now, and let us ensure your hot water is safe from scalding risks.