English
Installation and operating instructions Wilo-MVI 10, 15, 30, 50, 80
9
• No special maintenance in operation.
• Keep the pump and the motor perfectly clean.
• In case of prolonged stopping, if there is no risk of
frost, it is best not to drain the pump.
• The bearing holding the coupling is lubricated for its
total lifetime and does not require any lubrication. It
is recommended to grease the motor shaft end as
well as the coupling boring with a high adhering
grease (type type D321R Molikote or 8191 Loctite
for example) to facilitate any further diassembling.
Motors without lubricating devices
• Bearings are lubricated for their lifetime and do not
require any lubrication.
Motors with lubricating devices
• See instructions put on motor. If missing, lubricate
every 5 000 hours with a grease resistant to high
temperature.
Mechanical seals
• The mechanical seal does not require any mainte-
nance in operation. It must never operate dry.
10 Faults, causes and remedies
If the fault cannot be remedied, please contact
your local sanitary and heating specialist or WILO
customer services.
WARNING! Electrical shock hazard
Dangers caused by electrical energy must be
excluded.
All electrical work must be performed after the
electrical supply has been switched off and
secured against unauthorized switching.
WARNING! Risk of scalding
At high water temperatures and system pressure
close isolating valves before and after the pump.
First, allow pump to cool down.
DEFAULTS/CAUSES
REMEDIES
1) Pump turns but no delivery
a) The internal parts are obstructed by particles
b) Suction pipe obstructed
c) Air in suction pipes
d) Pump has lost it’s prime
e) Suction pressure is too low, it causes cavitation noise
f)
The supply voltage of the motor is too low
a) Dismantle the pump and clean it
b) Clean all the pipes
c) Check tightness of the whole pipe up to the pump and make
it tight
d) Fill the pump to prime again. Check foot valve is tight
e) Too high loss of head on suction or suction head (check the
NPSH of the pump installed and of the installation)
f)
Check the voltage on the terminals of the motor and the
cross-section of the conductors
2) The pump vibrates
a) Loose on its foundation
b) Particles obstructing the pump
c) Rotation variances
d) Bad electrical connection
a) Check and tighten completely the nuts of the stud bolts
b) Dismantle the pump and clean it
c) Check the pump turns freely without abnormal sticking
d) Check the connections to the pump motor
3) The motor overheats
a) Voltage too low
b) Pump obstructed by particles
c) Ambient temperature above +40 °C
d) Election connection problem in terminal box
e) Phase imbalance on three phase
a) Check voltage on terminals of the motor, it should be within
±
10 % in 50 Hz or
±
6 % in 60 Hz of the rated voltage
b) Dismantle the pump and clean it
c) The motor is aimed at operating at a maximum ambient tem-
perature of + 40°C
d) Be in conformity with the motor plate and see figure 4
e) Check amperage at each leg, if more than 5 % variance total
call electrician to balance (rotate all three legs)
4) The flow is irregular
a) The suction head (HA) is not adequate
b) The suction pipe has a lower diameter than the one of the
pump
c) The strainer and the suction pipe are partially obstructed
a) Study again the installation conditions and the recommen-
dations described in this instruction
b) The suction pipe must have the same diameter as the suction
pump port
c) Remove and clean
WARNING! Health hazard
If the liquid is toxic, corrosive or dangerous for
human being, WILO must be informed or the qual-
ified person in charge of the repairing. In this
case, clean the pump to ensure a complete safety
to the repairing man.
