APPENDIX 5 TO Legionella Procedure

Thermostatic Mixer Testing Procedure

  • Carry out servicing in accordance with the manufacturers recommendations.
  • Strip down and remove each valve and strainer from the main body.
  • De-scale and flush out all working parts of the valve and all strainer filters with an approved de-scaling agent.
  • Lubricate all spindles, seats etc. with silicon grease.
  • Replace any defective “O” rings.
  • Re-assemble valves and strainers and set working outlet temperature to a maximum of 43C for showers and a maximum of 41ºC for wash hand basins.
  • De-scale and sterilise all shower heads with an approved de-scaling/sterilising agent.
  • Check that the shower hose does not trail into the shower tray/bath etc. fix up as necessary.
  • Ensure that all automatic drain valves have been removed.
  • Inspect, service, clean and grease all isolating valves, non-return valves and strainers associated with the mixing valve. Ensure that non-return valves are installed.
  • Inspect shower pumps where fitted for correct operation, service to manufacturers recommendations.
  • Ensure that the maximum pipe run from the TMV to the outlet does not exceed 2m.
  • Check to ensure that the required mixed temperature at the furthest outlet is reached within 30 seconds; ensure that the operation of one outlet does not affect the discharge temperature of another.
  • Carry out a cold failsafe shut-off test by isolating the cold water supply to the TMV. Wait 5 seconds, if water is still flowing, check the temperature is below 45ºC.
  • Carry out a check to ensure that the input to the TMV should be at least 50ºC within a minute of running the water.
  • Digital thermometers of known accuracy, with a minimum refresh rate of 4 times a second shall be used; liquid filled thermometers shall not be used. Temperature readings shall be taken at the normal flow rate after allowing the system to stabilise. The hot and cold flow temperatures shall be recorded. Repeat temperature test at approximately ¼ normal flow rate Temperature range should be as required in Health Guidance Note: 'Safe' hot water and surface temperatures.
  • Log and record on service sheet all temperature settings.