25
FAULT DIAGNOSIS
Symptom
Cause/Rectification
1.
Only hot or cold
water from outlet.
a. Inlet supplies reversed (i.e. hot supply to cold inlet).
Check.
b. No hot water reaching mixing valve. Check.
c. Check strainers and inlet/outlet fittings for blockage.
d. Refer symptom
5
below.
e. Installation conditions continuously outside operating
parameters: refer to
SPECIFICATION
and
2e
below.
2.
Fluctuating or
reduced flow rate.
3
. No flow from
mixing valve
outlet.
a. Check strainers and inlet/outlet fittings for blockage.
b. Hot or cold supply failure; thermostat holding correct
shutdown function: rectify, and return to
2e
above.
4.
Blend temperature
drift.
Indicates operating conditions changed.
a. Refer to symptom
2
above.
b. Hot supply temperature fluctuation.
c. Supply pressure fluctuation.
5.
Hot water in cold
supply or vice
versa.
Indicates checkvalves require maintenance, refer to
MAINTENANCE
.
6.
Maximum blend
t e m p e r a t u r e
setting too hot or
too cool.
a. Indicates incorrect
maximum temperature setting
;
refer to
COMMISSIONING
.
b. As symptom
4
above.
c. As symptom
5
above.
7.
Water leaking from
valve body.
Seal(s) worn or damaged.
Obtain Service Pack (408 92/87), and renew all seals.
If leak persists from around temperature spindle, renew
Thermostatic cartridge.
Normal function of mixing valve when operating conditions
are unsatisfactory.
a. Check strainers and inlet/outlet fittings for flow restriction.
b. Assure that minimum flow rate is sufficient for supply
conditions.
c. Assure that dynamic inlet pressures are nominally
balanced.
d. Assure that inlet temperature differentials are sufficient.
e. Check thermostatic performance; renew Thermostatic
cartridge if necessary.