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Commissioning and in-service tests
Commissioning
Purpose
Since the installed supply conditions are likely to be
different from those applied in the laboratory tests it is
appropriate, at commissioning, to carry out some simple
checks and tests on each mixing valve to provide a
performance reference point for future in-service tests.
Procedure
1. Check that:
a) the designation of the thermostatic mixing valve
matches the intended application
b) the supply pressures are within the range of
operating pressures for the designation of the
valve
c) the supply temperatures are within the range
permitted for the valve and by guidance infor-
mation on the prevention of legionella etc.
2. Adjust the temperature of the mixed water in
accordance with the manufacturer's instructions
(page 62) and the requirement of the application
and then carry out the following sequence:
a) record the temperature of the hot and cold
water supplies
b) record the temperature of the mixed water at
the largest draw-off flow rate
c) record the temperature of the mixed water at
a smaller draw-off flow rate, which shall be
measured
d) isolate the cold water supply to the mixing
valve and monitor the mixed water temperature
e) record the maximum temperature achieved as
a result of (d) and the final stabilised tempera-
ture
NOTE: The final stabilised mixed water tempera-
ture should not exceed the values in Table A.
f)
record the equipment, thermometer etc. used
for the measurements
Table A: Guide to maximum stabilised temperatures
recorded during site tests
Application
Shower
Washbasin
Bath (44°C fill)
Bath (46°C fill)
The mixed water temperature at terminal fitting should
never exceed 46ºC.
72
Mixed water
temperature
43°C
43°C
46°C
48°C
If there is a residual flow during the commissioning or
the annual verification (cold water supply isolation test),
then this is acceptable providing the temperature of
the water seeping from the valve is no more than 2°C
above the designated maximum mixed water outlet
temperature setting of the valve.
Temperature readings should be taken at the normal
flow rate after allowing for the system to stabilise.
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 re-tested in accordance with the
manufacturers' instructions.
In-service tests
Purpose
The purpose of in-service tests is to regularly monitor
and record the performance of the thermostatic mixing
valve. Deterioration in performance can indicate the
need for service work on the valve and/ or the water
supplies.
Procedure
1. Carry out the procedure 2. (a) to (e) on page 70
using the same measuring equipment, or equipment
to the same specifications.
2. If the mixed water temperature has changed
significantly from the previous test results (e.g. > 1
K), record the change and before re-adjusting the
mixed water temperature check:
a) that any in-line or integral strainers are clean
b) any in-line or integral check valves or other
anti-backsiphonage devices are in good work-
ing order
c) any isolating valves are fully open
3. With an acceptable mixed water temperature,
complete the procedure 2. (a) to (e) on page 70.
4. If at step 2. (e) on page 70 the final mixed water
temperature is greater than the values in Table A
and / or the maximum temperature exceeds the
corresponding value from the previous test results
by more than about 2 K, the need for service work
is indicated.
NOTE: In-service tests should be carried out with a
frequency which identifies a need for service work
before an unsafe water temperature can result. In
the absence of any other instruction or guidance,
the procedure described in „Frequency of in-service
tests" may be used.
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