Wilo COF-2 Helix Mode D'emploi page 20

English
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
frequently
The low-water protection activates
frequently
20
Cause
Air intake on suction side
Foot valve strainer is permeable or
obstructed
Significant friction losses on the suction
side
Municipal water supply pressure too low
or zero
Negative suction head over reservoir 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 See the preceding chapter, fault "At least
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 installation capacity (or
reservoir of insufficient capacity)
Vessel pre-inflation level does not
conform
Water storage vessel pierced
Low-water cut-out switch is set too
high
Municipal water supply pressure drops
when pumps activate
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 replenishment
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 is 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, proceed 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.
one of the two pumps does not start".
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 reservoir that has greater
capacity.
Proceed to inflate the vessel.
Replace the vessel.
Adjust and correct the cut-out switch
settings.
Adjust the low-water cut-out switch to a
minimum. If the issue persists, the
municipal water supply is insufficient;
check the pressure gauge reading when
the pumps start up, or consult the
municipal water supplier.
WILO SE 11/2019