Problems, Causes And Remedies - Wilo -MVIL Einbau- Und Betriebsanleitung

8. Problems, causes and remedies

Faults
The pump turns but not delivery
The pump vibrate
The motor overheats
The pump delivers insufficient pressure
The circuit-breaker device is on
The flow is irregular
If no solution can be found, please contact your
plumbing and heating specialist or your nearest
Wilo Customer Service or representative.
Installation and operating instructions - Wilo-MVIL
Causes
The internal parts are obstructed by
particles
Suction pipe obstructed
Air in suction pipes
Pump is no more primed
Suction pressure is too low, it causes
cavitation noise
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
Voltage too low
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...)
The motor is defective
Bad filling of the pump
The motor turns in the wrong way
(three-phase motor)
The drain-priming plug is not correctly
tightened
The supply voltage of the motor is too
low
The setting of the thermal relay is not
adequate (too low)
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
partially obstructed
Remedies
Dismantle the pump and clean it
Clean all the pipes
Check tightness of the whole pipe up to
the pump and make it tight
Fill the pump to prime again
Check foot valve is tight
Too high loss of head on suction or suc-
tion head (check the NPSH of the pump
installed and of the installation)
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 it
Check the pump turns freely without
abnormal sticking
Check the connections to the pump motor
Check voltage on terminals of the motor,
it should be within ± 10 % in 50 Hz or ±
6 % in 60 Hz of the rated voltage
Dismantle the pump and clean it
The motor is aimed at operating at a
maximum ambient temperature of
+ 40°C
Be in conformity with the motor plate
and see figure 4
Dismantle the pump and solve the defect
Replace the motor
Open the bleeding device and drain until
there are no more air bubbles
Reverse the sense of rotation by interch-
anging the two phase wires on the motor
terminal box
Check it and screw it again
Check the voltage on the terminals of
the motor and the cross-section of the
conductors
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
English
15