20. Fault finding
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
breaker cabinet or controller.
‐ Make sure that the power supply is disconnected and
cannot be accidentally switched on.
20.1 System does not run when started
System does not run when started.
Cause Remedy
The actual pressure is higher
than or equal to the setpoint
set.
Wait until the pressure has
dropped, or lower the pressure on
the outlet side of the system, and
check that the system starts.
The power supply is
disconnected.
Connect the power supply.
The circuit breakers have cut
out.
Correct the fault and cut in the
circuit breakers.
The internal motor protection is
activated.
Contact Grundfos.
The circuit breaker is defective. Replace the circuit breaker.
The motor is defective. Repair or replace the motor.
Outlet-pressure sensor fault.
• The outlet-pressure sensor
is defective.
• The cable is broken or
short-circuited.
• Replace the outlet-pressure
sensor.
• Repair or replace the cable.
20.2 System starts but stops immediately afterwards
System starts but stops immediately afterwards. The operating
pressure is not reached.
Cause
Remedy
Dry running or no inlet
pressure.
Check the supply of water to the
system. When the inlet pressure
has been re-established, the
pumps will restart after 15
seconds.
20.3 System stops and cannot restart
System stops and cannot restart.
Cause
Remedy
Outlet-pressure sensor fault.
• The outlet-pressure sensor
is defective.
• The cable is broken or
short-circuited.
• Replace the outlet-pressure
sensor. Outlet-pressure
sensors with 0-20 mA or 4-20
mA output signals are
monitored by the system.
• Repair or replace the cable.
Terminal box unit fault.
• The power supply is
disconnected on pump 1.
• The terminal box is
defective.
• Connect the power supply.
• Replace the terminal box of
pump 1.
• Contact Grundfos.
20.4 Unstable water supply from system
Unstable water supply from system (only applies to very low
consumption).
Cause
Remedy
The inlet pressure is too low. Check the inlet pipe and possible
inlet strainer.
The inlet pipe or pumps are
partly blocked by impurities.
Clean the inlet pipe or pumps.
Cause Remedy
The pumps suck air. Check the inlet pipe for leakages.
The outlet-pressure sensor is
defective.
Replace the outlet-pressure
sensor.
20.5 Pumps are running but deliver no water
Pumps are running but deliver no water.
Cause Remedy
The inlet pipe or pumps are
blocked by impurities.
Clean the inlet pipe or pumps.
The non-return valve is blocked
in the closed position.
Clean the non-return valve. The
non-return valve must move
freely.
The inlet pipe is leaky. Check the inlet pipe for leakages.
Air in inlet pipe or pumps. Vent the pumps. Check the inlet
pipe for leakages.
20.6 System is unable to reach the setpoint
System is unable to reach the setpoint.
Cause Remedy
The cable is broken or short-
circuited (GENIbus
communication between pump
1 and pump 2 or 3).
Repair or replace the cable.
Pump 2 or 3 is out of operation. Connect the power supply to the
pump and check the pump
condition.
20.7 Leakage from a shaft seal
Leakage from a shaft seal.
Cause
Remedy
The shaft seal is defective. Replace the shaft seal.
CRE and CRIE pumps:
The height adjustment of the
pump shaft is inaccurate.
Re-adjust the shaft height.
20.8 There is noise when the pumps are operating
There is noise when the pumps are operating.
Cause
Remedy
The pumps are cavitating. Clean the inlet pipe or pumps and
possibly the inlet strainer.
CRE and CRIE pumps:
The pumps do not rotate freely
(frictional resistance) due to
inaccurate height adjustment of
the pump shaft.
Re-adjust the shaft height. See
the CR, CRI, CRN installation
and operating instructions
supplied with system.
20.9 Very frequent starts and stops
Very frequent starts and stops.
Cause
Remedy
Wrong diaphragm tank
precharge pressure.
Check the precharge pressure.
The difference between start
and stop pressures is too small.
This situation will only
arise if emergency
operation is installed.
Increase the differential pressure
setting on each pressure switch.
42
English (GB)
To Next Page
Loading...
Need help?
General
