Wilo WEH, Installation And Operating Instructions Manual

Page: 11 / 20

WILO SE 02/2014 7
English
10. Problems, causes and remedies
DANGER! SWITCH OFF the pressure-maintaining system before any maintenance or repair work.
Problems Causes Remedies
One or two pumps fail to prime Air leaks at the suction side Check tightness of tall suction pipe con-
nections
Check that the level of suction in tank is
covered
Large delivery head losses at suction
side
Calculate the head losses and make sure
they are compatible with the pump NSPH
Suction piping obstructed or valve on
suction manifold closed
Check valve opening and clean the pip-
ing if necessary
One pump not running Thermal relay tripped The pump "fault" indicator on the
switchgear must be lit.
Check the setting of the thermal relay
and reset it.
Check the direction of rotation, the
coupling or the current requirements of
the motor concerned
Magnetic circuit breaker or fuses defect-
ive or blown
Check that the motor phases are not in
short-circuit between them. Replace the
motor if necessary.
Reset the circuit breaker or replace the
fuses (check their ratings).
Pump shaft blocked Switch off the electric supply of the
switchgear and then check if the shaft
turns smoothly; if it is blocked, dismantle
the pump
Winding fault Disconnect the terminal board of the
terminal block and check the stator
insulation to earth. Replace the motor if
necessary
No delivery pressure Flow higher than the capability of the
pressure-maintaining system
Plan to replace the system by a more
adequate one (do not forget to contact
us in any case).
One or two pumps do not prime any-
more
Check that the suction strainer does not
let air in or the tank filling point is too
close from the strainer
A pump is obstructed by particles Have the pump dismantled and cleaned
Voltage of the motors too low Check the voltage on motor terminals
Random operating, starting frequency
too high
Pressure transmitter defective Check the setting: transmitter not stable,
replace it if necessary
Discharge valve not well adjusted or no
longer watertight
Check adjustment of discharge valve,
check the state of device, change com-
ponents if necessary
Tripping frequency of dry running safety
too high
Float switch not well positioned or not
working
Check the position of float switch,
change it if necessary
Flow higher than the capability of the
pressure-maintaining system
It could be necessary to replace the sys-
tem (Consult us for this)
Switchgear defective Switchgear or cabinet defective See commissioning instructions of the
switchgear or cabinet
Wires disconnected Check all connections to the terminal
block of the switchgear
Transmitter defective Check the contacts; change the trans-
mitter concerned if necessary
Delivery check, valve not tight Valve diaphragm or ring destroyed Change the valves
The pressure-boosting system does not
stop or start
The shut-off valve is closed Open the shut-off valve (pos. 16)
Water fall on top of tank Float switch for filling defective Check the float switch, change it if
necessary.
The float switch transmits information
for the electrovalve of tank filling
11. Spare parts
Spare parts are ordered via a local specialist dealer and/or the Wilo customer service.
In order to avoid queries and incorrect orders, make sure to mention all data indicated on the rating plate when
placing your order.
Subject to change without prior notice.