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I N - S E R V I C E T E S T S
P U R P O S E
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.
P R O C E D U R E
1. Carry out the procedure 2. (a) to (e) on page 77 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 chan-
ge 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 working order
c) any isolating valves are fully open
3. With an acceptable mixed water temperature, complete
the procedure 2. (a) to (e) on page 77.
4. If at step 2. (e) on page 77 the final mixed water tempe-
rature 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 fre-
quency 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.
F R E Q U E N C Y O F I N - S E R V I C E T E S T S
T M V 3 *
G E N E R A L
In the absence of any other instruction or guidance on the
means of determining the appropriate frequency of in-service
testing, the following procedure may be used:
1. 6 to 8 weeks after commissioning carry out the tests given
in 2. on page 77.
2. 12 to 15 weeks after commissioning carry out the tests
given in 2. on page 77.
3. Depending on the results of 1. and 4. several possibilities
exist:
a) If no significant changes (e.g. < 1 K) in mixed water
temperatures are recorded between commissioning
and 1., or between commissioning and 4. the next
in-service test can be deferred to 24 to 28 weeks
after commissioning.
b) If small changes (e.g. 1 to 2 K) in mixed water tem-
peratures are recorded in only one of these periods,
necessitating adjustment of the mixed water tempe-
rature, then the next in-service test can be deferred
to 24 to 28 weeks after commissioning.
c) If small changes (e.g. 1 to 2 K) in mixed water
temperatures are recorded in both of these periods,
necessitating adjustment of the mixed water tempe-
rature, then the next in-service test should be carried
out at 18 to 21 weeks after commissioning.
d) If significant changes (e.g. > 2 K) in mixed water
temperatures are recorded in either of these periods,
necessitating service work, then the next in-service
test should be carried out at 18 to 21 weeks after
commissioning.
4. The general principle to be observed after the first 2 or
3 in-service tests is that the intervals of future tests should
be set to those which previous tests have shown can be
achieved with no more than a small change in mixed water
temperature.
*TMV2: The frequency of performing the in-service tests is
1 year maximum.
