Faults, Causes And Remedies - Wilo COF-2 BL Installation And Operating Instructions Manual

10 Faults, causes and remedies

Troubleshooting, particularly of problems relating
to the pumps and switchgear, must be performed
exclusively by a Wilo customer service agent or a
specialist firm.
NOTICE:
When carrying out all maintenance and repair
work, it is crucial that the general safety instruc-
Fault
At least one of the two pumps does
not start
One pump does not start
No pressure on the discharge side
Random operation, pumps start fre-
quently
Installation and operating instructions Wilo-COF-2 BL
Cause
If the reservoir is in suction
mode, there is possible air
intake upon suction
If the reservoir is in suction
mode, it is possible that the
strainer foot valve is permeable
or obstructed
Significant friction losses on the
suction side
Municipal water supply pressure
too low or zero
If the reservoir is in suction
mode, then the negative suc-
tion head may be too great
Suction pipework obstructed or
valve on suction manifold
closed
Thermal motor protection
activated
Magnetic circuit breaker
activated
Pump shaft blocked
Winding malfunction
At least one of the pumps is
deactivated
Municipal water supply pressure
below minimum prescribed
pressure
One pump is obstructed by
foreign bodies
The motors are supplied by
insufficient power supply
voltage
Pressure sensor is defective
Insufficient system capacity
(or tank of insufficient capacity)
Tank pre-inflation level does
not conform
Water storage vessel pierced
tions are observed! It is also important to follow
the installation and operating instructions for the
pumps and switchgear.
Danger! Risk of death!
Only specialist and appropriately qualified per-
sonnel may perform troubleshooting!
Observe the safety instructions in Chapter 9.
Remedy
Check the impermeability of all connections in the
suction pipework.
Check that the suction strainer is properly submerged
in water.
Check the impermeability of the valve and replace it
if necessary.
Check the friction losses and make sure that they are
compatible with the NPSH of the pumps.
Adjust the system to supply the pressure-boosting
system from a reservoir.
Ensure that the minimum level of the reservoir is
compatible with the pumps' NPSH.
Check that the valve is open and clean pipework if
necessary.
The pump "malfunction" warning light on the
switchgear must be illuminated. Check the thermal
motor protection settings and reset.
Check that the motor phases have not short-
circuited.
Replace the motor if necessary.
Reset the circuit breaker.
Disconnect the switchgear power supply, then check
that the pump shaft turns freely. If it is blocked, pro-
ceed to dismantle the pump.
Disconnect the terminal of the motor concerned and
check the resistor at the terminals and the stator's
insulation to earth.
Replace the motor if necessary.
See the preceding chapter, fault "At least one of the
two pumps does not start" and refer to the pump
installation instructions.
Contact the local water supplier or replace the
pressure-boosting system. Contact us.
Dismantle and clean the pump.
Check the voltage and the connection to motor
terminals.
Check settings: if sensor is unstable, it must be
replaced.
Install an additional storage tank or replace with a
tank that has greater capacity.
Proceed to inflate the tank.
Replace the vessel.
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