ENGLISH
8 Faults, causes and remedies
Faults
Possible cause
Remedy
Pump does not start or
fails to run
Pump chocked up
switch off power supply, take-off pump head, remove
obstruction; if motor blocked, overhaul/exchange mo-
tor/pump head
Loose terminals
tighten all terminals
Defect fuses
check fuses, change defect fuses
Faulty motor
call service
Tripped overload relay
throttle hydraulic flow rate down to nominal at discharge
side of pump
Incorrectly set trip relay
reset thermal overloads to name plate FLC-value
Thermal overload are influ-
enced by excessive ambient
temperature
reposition overload relay or protect by thrmal insulation
Tripped PTC-relay
check motor and fan cover for dirt/dust accumulation and
clean if necessary; check ambient temperature and if
necessary, ensure an ambient temperature
d
40 °C by
forced ventilation.
Pump runs at reduced
incorrect rotation
check direction of rotation, if necessary
capacity
Discharge valve throttled too
far
slowly open isolating valve
Speed too low
correct wrong terminal bridging (Y in lieu
'
)
Air in suction pipe
check and correct flange leakages, eventually vent pipe
section
Pump makes noise
insufficient inlet pressure
raise inlet pressure, ensure minimum required inlet pres-
sure at suction port, check and if necessary clean suc-
tion-side isolating valve and strainer
Faulty motor bearings
Arrange for pump to be inspected and, if necessary, to be
repaired by Wilo or other authorized service.
Impeller scratches
Test the contact between lantern and pumphousing.
Clean it, if necessary.
If the fault cannot be remedied, please contact your local plumbing and heating specialist or
WILO customer services.
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