Wilo Economy MHIL, Installation And Operating Instructions Manual

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If the fault cannot be remedied, please contact your plumbing and
heating specialist or WILO customer services.
Subject to technical alterations.
Fault
Pump turns but no delivery
The pump vibrates
The motor overheats
The pump delivers insufficient pressure
The circuit-breaker device is on
The flow is irregular
Cause
The internal parts are obstructed by par-
ticles
Suction pipe obstructed
Air in suction pipes
Pump is no more primed
Suction pressure is too low, it causes cavi-
tation noise
The pump turns in the wrong sense
(3~ motor)
The supply voltage of the motor is too low
Loose on its foundation
Particles obstructing the pump
Difficult rotation of the pump
Bad electrical connection
Too low voltage
Pump obstructed by particles
Ambient temperature above 40°C
Coupling failure in the terminal box
The motor fails to run at its normal speed
(particles, inadequate motor supply ...)
The motor is defective
Bad filling of the pump
The motor turns in the wrong way (three-
phase motor)
The supply voltage of the motor is too low
Too low value of the thermal relay
(3~ motor)
The voltage is too low
A phase is cut
The thermal relay of the circuit-breaker is
defective
A fuse is off
The suction head (Ha) is not adequate
The suction pipe has a lower diameter than
the one of the pump
The strainer and the suction pipe are partial-
ly obstructed
Remedy
Dismantle the pump and clean
Clean all the pipes
Check tightness of the whole pipe up to the
pump and seal it
Fill the pump to prime again. Check foot
valve is tight
Too high losses of head on suction or suc-
tion head is too high (check the NPSH of
the installed pump)
Cross the two phase wires on motor ter-
minal block or motor-overload release to
reverse the sense of rotation
Check the voltage on the terminals of the motor
and the cross-section of the conductors
Check and tighten completely the nuts of
the stud bolts
Dismantle the pump and clean
Check the pump turns freely without abnor-
mal sticking
Check the connections of the pump
Check voltage on terminals of the motor, it
should be within ± 10 % of the rated vol-
tage
Dismantle the pump and clean
The motor is aimed at operating at a maxi-
mum ambient temperature of 40°C
To conform to the motor plate
Dismantle the pump and solve the defect
Replace the motor
Fill the pump and drain until there are no
more air bubbles
Reverse the sense of rotation by interchan-
ging the two phase wires on the motor ter-
minal box or motor-overload release
Check the voltage at the terminals of the
motor and the cross-section of the conduc-
tors and of the coupling
Check the current with an ammeter or set
the value of the current rating on the motor
data plate
Check the adequate cross-section of the
conductors of the electrical cable
Check it and change the electrical cable if
necessary
Replace it
Replace it
Study again the installation conditions and the
recommendations described in this instruction
The suction pipe must have the same
diameter as the suction pump port
Remove and clean
8. Fault finding, causes and remedies
If the liquid is toxic, corrosive or dangerous for human being,
WILO must be informed or the qualified person in charge of
the repairing. In this case, clean the pump to ensure o com-
plete safety to the repairing man.
13 WILO SE 04/2016
English