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Installation and operating instructions Wilo domestic water systems HiMulti3..H.. /HMHI/HWJ 31
• The gas supply pressure (PN2) should approxi-
mately correspond to the pump switch-on pres-
sure (pI) less 0.2-0.5 bar or 10% of the pump
switch-on pressure (pI) (see Table 1), replenish to
correct. When replenishing, we recommend using
nitrogen because this gas minimises the risk of
corrosion in the tank.
• Check the pump for leaks.
• Clean and maintain filters installed as accessories
regularly (in accordance with the corresponding
installation and operating instructions).
Afterwards, commission the domestic water
system (see section 8).
10 Faults, causes and remedies
Faults, particularly those affecting the pumps or
the control system, should only be remedied by
Wilo’s customer service or a specialist company.
NOTE:
The general safety instructions must be observed
during any maintenance or repair work.
Also follow the installation and operating instruc-
tions of the pumps and the control device or any
accessories present.
Faults Causes Remedy
Motor does not run No mains voltage Check fuses, float switch and cable
Fuse defective Replace fuse
Motor protection tripped Remedy motor overload
Pump not running smoothly Remedy pump clogging
Pump blocked Remedy blockage of the pump
Dry-running protection tripped, water
level too low
Check water level and correct
Pump defective Replace pump
Pump is running but not pumping Incorrect direction of rotation DM version: Swap 2 phases of the mains
connection
EM version: contact customer service
Supply voltage too low Check mains voltage, capacitor and
cables
Pipe or parts of the pump are blocked by
foreign objects
Check and clean pipe and pump
Air in suction port Seal inlet pipe
Air in the pump Fill the pump again
Inlet pipe or suction line too narrow Install an inlet pipe or suction line with
a larger nominal diameter
Immersion depth of the foot valve too
low
Increase immersion depth of the foot
valve
Pump is not pumping evenly Suction head too large Position pump lower
Pressure is not adequate Incorrect pump selected Install a more powerful pump
Incorrect direction of rotation DM version: Swap 2 phases of the mains
connection
EM version: contact customer service
Flow rate too low, inlet pipe or filter
blocked
Clean filter and inlet pipe
Shut-off device not opened sufficiently Open shut-off device
Foreign object is blocking the pump Clean pump
Pump vibrating Foreign object in the pump Remove the foreign object
Pump not running smoothly Check smooth running of the pump/
motor
Cable terminals loose Check cable terminals of the motor
and secure
Pump not adequately secured to the
tank
Tighten fastening screws
Bearing surface is not solid enough Stabilise the bearing surface
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