Grundfos CU 323 Series - Fault Finding the Product; Troubleshooting Common Issues

English (GB)
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7. Fault finding the product
DANGER
Electric shock
Death or serious personal injury
- Switch off the power supply and wait at
least five minutes before you make any
connections in the pumps, terminal
boxes or control cabinet. Make sure that
the power supply cannot be accidentally
switched on.
Fault Possible cause Remedy
1. The pumps are not
running.
a) The actual pressure is higher
than or equal to the setpoint.
Wait until the pressure has dropped, or
lower the pressure on the outlet side of
the booster system. Check that the
pumps start.
b) The power supply has been
switched off.
Connect the power supply.
c) The main switch has cut out. Cut in the main switch.
d) The main switch is defective. Replace the main switch.
e) The motor protection has been
activated.
Contact Grundfos.
f) The motor is defective. Repair or replace the motor.
g) The pressure transmitter is
defective.
Replace the pressure transmitter.
0-10 bar or 0-6 bar transmitters with 0-10
V, 0-20 mA or 4-20 mA output signals are
monitored by the booster system.
h) The cable is broken or
short-circuited.
Repair or replace the cable.
2. The pumps start, but
stop immediately.
The operating
pressure is not
reached.
a) Water shortage or no inlet
pressure.
Re-establish the supply of water to the
booster system. When the inlet pressure
has been re-established, press [RESET]
to restart the system.
3. The booster system
is stopped and
cannot restart.
b) The pressure transmitter is
defective.
Replace the pressure transmitter.
0-10 bar or 0-6 bar transmitters with 0-10
V, 0-20 mA or 4-20 mA output signals are
monitored by the system.
c) The cable is broken or
short-circuited.
Repair or replace the cable.
d) The power supply to CU 323 has
been switched off.
Reconnect the power supply.
e) CU 323 is defective.
Contact Grundfos.
4. Unstable water
supply from the
booster system.
a) The inlet pressure is too low. Check the inlet pipe and the inlet
strainer, if any.
b) The inlet pipe, strainer or pumps
are partly blocked by impurities.
Clean the inlet pipe, strainer or pumps.
c) The pumps suck air. Check the inlet pipe for leakages.
d) The pressure transmitter is
defective.
Replace the transmitter.