English (GB)
7
8. Fault finding
* Or contact the nearest Grundfos company or service workshop.
Warning
Before starting fault finding, switch off the
power supply. Make sure that the power
supply cannot be accidentally switched on.
Fault Cause Remedy
1. The green "Power
on" indicator light is
off.
a) The fuses in the electric installation
have burnt.
Replace the fuses. If the new fuses also
burn, check the electric installation.
b) The earth leakage circuit breaker
or the voltage-operated circuit
breaker has tripped.
Cut in the circuit breaker and check the
electric installation.
c) The PM unit is defective. Repair or replace the PM unit.
2. The green "Pump
on" indicator light is
on, but the pump
does not start.
a) The power supply to the pump is
disconnected after the PM unit.
Check the cable connections.
b) The motor protection of the pump
has tripped due to overload.
Check if the motor/pump is blocked.
Clean if necessary.
c) The pump is defective. Repair or replace the pump.*
d) The PM unit is defective. Repair or replace the PM unit.*
3. The pump does not
start when water is
consumed.
The "Pump on"
indicator light is off.
a) Too big difference in height
between the PM unit and the
tapping point.
Reposition the pump, or select a PM unit
with a higher start pressure.
b) The PM unit is defective. Repair or replace the PM unit.*
4. Frequent
starts/stops.
a) Leakage in the pipework. Check and repair the pipework.
b) Non-return valve of the PM unit is
leaking.
Clean or replace the non-return valve.
5. The pump does not
stop.
a) The PM unit is defective. Repair or replace the PM unit.
b) Non-return valve of the PM unit is
stuck in open position.
Clean or replace the non-return valve.
6. The red "Alarm"
indicator light is on.
a) Dry running. Check the water supply.
b) The power supply to the pump is
disconnected after the PM unit.
Check the cable connections.
c) The motor protection of the pump
has tripped due to overload.
Check if the motor/pump is blocked.
Clean if necessary.
d) The pump is defective. Repair or replace the pump.*
e) The PM unit is defective. Repair or replace the PM unit.*
7. The red "Alarm"
indicator light is
flashing.
a) Cycling. A tap has not been closed
entirely after use.
Check that all taps have been closed.
b) Cycling. The membrane is
defective.
Replace the membrane.
8. The motor cuts out
during operation.
a) The thermal switch in the motor
has tripped due to overheating.
The thermal switch will cut in
automatically when the motor has cooled
sufficiently.
If the problem still persists, check these
two possible causes:
• Impeller stuck.
Clean the pump.
• Motor defective.
Repair or replace the motor.*
