English (GB)
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4. Fault finding chart
5. Disposal
This product or parts of it must be disposed of in an
environmentally sound way:
1. Use the public or private waste collection service.
2. If this is not possible, contact the nearest
Grundfos company or service workshop.
Subject to alterations.
Warning
Before removing the terminal box cover, make sure that the electricity supply has been
switched off and that it cannot be accidentally switched on.
Fault Cause Remedy
1. The pump does not run.
None of the indicator lights
are on.
a) One fuse in the installation is
blown.
Replace the fuse.
b) External mains switch
switched off.
Switch on the mains switch.
c) Current-/voltage-operated
earth-leakage circuit breaker
has tripped out.
Repair insulation defects and cut in
the circuit breaker.
2. The pump does not run.
The green indicator light is
on.
a) Rotor blocked, but the pump
has not been cut out by the
thermal overload switch.
Switch off the electricity supply and
clean/repair the pump.
3. The pump does not run.
The red indicator light is on.
The green indicator light is
off.
a) The pump has been cut out
by the thermal overload
switch due to high liquid
temperature or blocked rotor.
Check that the liquid temperature
falls within the specified range.
The pump will restart automatically
when it has cooled to normal
temperature.
b) The speed switch module has
not been fitted.
Switch off the electricity supply by
means of the external mains switch
and fit the speed switch module.
4. The pump is running.
The red indicator light is on.
The green indicator light is
on.
a) The pump is running with
wrong direction of rotation
(only three-phase pumps).
Switch off the electricity supply by
means of the external mains switch
and interchange two phases in the
terminal box.
5. Noise in the system.
The green indicator light is
on.
a) Air in the system. Vent the system.
b) The pump flow is too high. Reduce the pump performance
(change to lower speed).
c) The pressure is too high. Reduce the pump performance
(change to lower speed).
6. Noise in the pump.
The green indicator light is
on.
a) Air in the pump. Vent the pump.
b) The inlet pressure is too low. Increase the inlet pressure and/or
check the air volume in the
expansion tank (if installed).
7. Insufficient heat in some
places in the heating
system.
a) The pump performance is too
low.
Increase the pump performance
(change to higher speed), if possible,
or replace the pump with a pump
with a higher flow.