18
The following procedures should be carried out after installation and every 12 months after to ensure
that the valve is functioning correctly.
Check that:
1. The application of the thermostatic valve matches the approved designation.
2. The supply pressures are within the recommended range for the application.
3. The supply temperatures are within the permitted range for the application and comply with the
guidance for prevention of Legionella.
4. The mixed temperature is as required for the application.
Record:
5. Each hot and cold supply. (Make a note of the measuring device used).
6. The mixed water temperature at the outlet device.
Isolate:
7. The cold supply to the mixing valve and record the mixed water temperature after about 5 seconds.
The temperature should not exceed the value given in table (2) below.
The purpose of servicing regularly is to monitor the performance of changes in system and valve set
up. This may require the need to adjust either the supply system or the valve. The product should be
checked and tested 12 months after commissioning.
Firstly measure the water temperature at one of the outlets (bath fill or shower).
Carry out the cold water supply isolation test by isolating the cold water supply to the TMV, wait for 5 sec-
onds if water is still flowing check that the temperature is below 45°C. If there is no significant change
to the set outlet temperature (+/-2ºC or less change from the original settings) and the fail-safe shut off
is functioning, then the valve is working correctly and no further service work is required.
Notes:
A residual flow is permitted during the commissioning or the annual verification (cold water supply
isolation test), then this is acceptable providing the water temperature is no more than 2ºC above the
designated outlet temperature.
Temperature readings should be taken at the normal flow rate after allowing for the system to stabilize.
The sensing part of the thermometer probe must be fully submerged in the water that is to be tested.
Any TMV that has been adjusted or serviced must be re-commissioned and retested in accordance with
the instructions detailed above.
Note:
46°C is the maximum mixed water temperature from a bath tap. The maximum temperature
takes account of the allowable temperature tolerances inherent thermostatic mixing valves and tem-
perature loss in metal baths.
It is not a safe bathing temperature for adults and children.
The British Burns Association recommends 37°C-37.5°C as a comfortable bathing temperature for Children.
In premises covered by the Care Standards Act 2000, the maximum mixed water temperature is 43°C
Table 2 A guide to maximum temperature sets
Application
Mixed water temperature
Permitted maximum temperature
rise during site testing
Shower
41°C
43°C
10
COMMISSIONING & PERIODIC CHECKS
11 FREQUENCY OF REGULAR SERVICING
