17
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 filters and inlet 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 filters 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.
Check inlet isolators are fully open.
5.
Hot water in cold
supply or vice
versa.
Indicates check valves require maintenance, refer to
MAINTENANCE
.
Normal function of mixing valve when operating
conditions are unsatisfactory.
Indicates operating conditions changed.
a. Refer to symptom
2
above.
b. Hot supply temperature fluctuation (rectify and refer to
COMMISSIONING
).
c. Supply pressure fluctuation (refer to
INSTALLATION
;
General).
d. Valve requires servicing. Fit ‘O’ Seal pack.
e. Fit new thermostat pack.
a. Check filters and inlet/outlet fittings for flow restriction
(check isolators are fully open).
b. Ensure that minimum flow rate is sufficient for supply
conditions.
c. Ensure that dynamic inlet pressures are nominally
balanced.
d. Ensure that inlet temperature differentials are sufficient.
e. (subsequent to rectification of supply conditions) Check
thermostatic performance; renew thermostat assembly
if necessary.
(Continued)
