Wilo ISAR MODH1 Series, Installation And Operating Instructions Manual

Page: 13 / 22

13
Fault Cause Remedy
Switching frequency too high or
fluttering
Major fluctuations of the inlet pressure Check the inlet pressure and take measures to
stabilise the inlet pressure if necessary
(e.g. pressure reducers)
Inlet pipe clogged or shut off Check the inlet pipe and remove the clogging
or open the shut-off valve if
necessary
Nominal diameter of the inlet pipe too small Check the inlet pipe and increase the cross-
section of the inlet pipe if necessary
Inlet pipe installed incorrectly Check the inlet pipe and change the pipe
routing if necessary
Shut-off device closed at pressure sensor Check and open the shut-off valve if
necessary
No diaphragm pressure vessel present
(optional or accessory)
Retrofit a diaphragm pressure vessel
Supply pressure at existing diaphragm
pressure vessel incorrect
Check the supply pressure and correct it if
necessary
Valve on existing diaphragm pressure vessel
closed
Check the valve and open it if necessary
Existing diaphragm pressure vessel defective Check the diaphragm pressure vessel and
replace if necessary
Switching difference set too low Check the setting and correct it if necessary
Pump(s) not stable and/or make(s)
unusual noises
Inlet pipe clogged or shut off Check the inlet pipe and remove the clogging
or open the shut-off valve if
necessary
Nominal diameter of the inlet pipe too
small
Check the inlet pipe and increase the cross-
section of the inlet pipe if necessary
Inlet pipe installed incorrectly Check the inlet pipe and change the pipe
routing if necessary
Air in the inlet Check and shut off the piping and vent the
pumps if necessary
Air in the pump Vent the pump, check the suction line for
leakages and seal it if necessary
Impellers clogged Check the pump and replace it or have it
repaired if necessary
Flow rate too high Check the pump data and default values and
correct if necessary
Incorrect direction of rotation of the motors Check direction of rotation and correct by
changing over phases if necessary
Mains voltage: a phase is missing Check the fuses, cables and connections
Pump not adequately secured to base
frame
Check the fixation and re-tighten the
fastening screws if necessary
Bearing damage Check the pump/motor and replace it or
have it repaired if necessary
Motor or pump become too warm Air in the inlet Check and shut off the piping and vent the
pumps if necessary
Gate valve in the system closed or not
sufficiently open
Check and open the shut-off valve completely
if necessary
Impellers clogged Check the pump and replace it or have it
repaired if necessary
Non-return valve clogged Check and remove the clogging or replace
the non-return valve if necessary
Shut-off device closed at pressure
sensor
Check and open the shut-off valve if
necessary
Deactivation point set too high Check the setting and correct it if necessary
Bearing damage Check the pump/motor and replace it or
have it repaired if necessary
Turn-to-turn fault in the motor Check, if necessary replace motor or have it
repaired
Mains voltage: a phase is missing Check the fuses, cables and connections