What is a TMV?

A TMV is short for Thermostatic Mixing Valve, they’re designed as an anti scald device to blend hot and cold water together at the outlet point so that the water is at a safe temperature to use. It also ensures that the valve shuts off if the cold water becomes isolated, preventing hot water being delivered to the outlet at a dangerous temperature.

How often should I have my TMV’s serviced? 

It is extremely important to service your TMV’s on a regular basis, 12 months being the minimum – depending on your sites outcome of a Risk Assessment or manufactures guidance.

Our specialist Water Hygiene & Health & Safety compliant engineers carry out TMV Servicing, management and installation – we can also answer any queries you may have!

Thermostatic mixing valves: Servicing

Manufacturers of TMV3 type valves recommend that they are serviced regularly to ensure they are working as designed.

Manufacturers can supply details of how too and how often the valves should be serviced.

TMV servicing should only be carried out by a qualified competent plumber.

All TMV valves are different but standard procedure is to:

  • Isolate hot & cold inlet supplies.
  • Disconnect the main valve body from the pipe work and clean the filters.
  • De-scale and disinfect the TMV valve and parts.
  • Clean the valve and connect back together.
  • Turn water supplies back on and test for leaks.
  • Turn hot tap on fully and run for 30 seconds and test check the temperature is within guidelines?
  • Adjust if required by using specified tools or keys to specified temp.
  • While tap is still running turn the cold supply off and check fail safe? = PASS/FAIL
  • If valve fails isolate the valve from use and inform responsible person.
  • Complete a TMV service sheet and report any faults to responsible persons

Older valves when disconnected and stripped can sometimes cause faults and damage the valves function so where a valve has passed its fail safe test and temperature is within guidelines and flows is sufficient then most plumbers will not strip or disconnect the valve to prevent any damage while the valve is safe and working correctly.

All manufacturers should have information on how to service their valves if required.

Important: action to take

You must take action if the water is too hot.

More than 44 degrees C from a bath

More than 41 degrees C from a shower or hand basin

  • If the water is too hot, record the temperature in a check sheet
  • Call a plumber and arrange for them to attend as soon as possible to check and reset the valve.
  • Stop anyone using the bath or shower until the plumber has called
  • Tell your manager and colleagues what you have done and why.
  • If bath/shower is needed for personal care before the plumber can attend, work out as a team how you will protect people from scolding until then.
  • Record the temporary safe system and ensure all staff members read, understand and sign it.

Tough Water regularly come across sights just like the images below. This is a TMV we were servicing and it was discovered that the TMV didn’t actually work, we dismantled it and the reasons were revealed as to why it no longer worked – I think the images say it all don’t you?

This is a TMV that hasn’t been regularly controlled and serviced, as they’re an anti-scold device, it is extremely important to have them regularly serviced in order for them to work correctly and efficiently.