20
8. Fault finding chart
See also section 6.6 Indicator lights.
Note: The R100 can also be used for fault finding.
Before removing the terminal box cover, make sure that the electricity supply has been switched off
for at least 5 minutes.
The pumped liquid may be scalding hot and under high pressure. Before any removal or dismantling
of the pump, the system must therefore be drained or the isolating valves on either side of the pump
must be closed.
Fault Cause Remedy
The pump is not running.
None of the indicator lights
are on.
One fuse in the installation is blown. Replace the fuse.
The current-operated or voltage-oper-
ated circuit breaker has tripped out.
Cut in the circuit breaker.
The pump is defective. Repair or replace the pump.
The pump is not running.
The green indicator light is
flashing.
The pump has been stopped in one of
the following ways:
1. With the button “–”.
2. With the R100.
3. External on/off switch in position
off.*
4. Via bus signal.*
1. Start the pump by pressing “+”.
2. Start the pump with the R100 or
by pressing “+”.
3. Switch on the on/off switch.*
4. Start the pump via bus signal.*
* The fault can be temporarily corrected by selecting max. curve duty on the pump
or with the R100, as external forced-control signals will be ignored.
The pump has stopped due to
a fault.
The red indicator light is on
and the green indicator light is
off.
Electricity supply failure (e.g. undervolt-
age).
Check that the electricity supply falls
within the specified range.
Missing phase (the pump runs for 2 min-
utes and then stops).
Check fuse and connections.
Pump blocked and/or impurities in the
pump.
Remove the inspection screw and
turn the rotor by means of a screw-
driver inserted into the slot in the
shaft end, and/or dismantle and clean
the pump.
Fault in electronics. Contact GRUNDFOS.
The pump is running, but has
been stopped due to a fault.
The red and green indicator
lights are on.
The differential pressure and tempera-
ture sensor is defective.
Check sensor connection. Replace if
necessary.
The pump has restarted automatically
after a temporary fault.
Reset fault indication.
The pump has been set to
stop, but has been stopped
due to a fault.
The red indicator light is on
and the green indicator light is
flashing.
The differential pressure and tempera-
ture sensor is defective.
Check sensor connection. Replace if
necessary.
The pump has restarted automatically
after a temporary fault.
Reset fault indication.
Noise in the system.
The green indicator light is
on.
Air in the system. Vent the system.
The flow is too high. Reduce the head (setpoint) and pos-
sibly change over to constant pres-
sure.
The pressure is too high. Reduce the head (setpoint) and pos-
sibly change over to proportional
pressure.
Noise in the pump.
The green indicator light is
on.
Air in the pump. Vent the pump.
The inlet pressure is too low. Increase the inlet pressure and/or
check air volume in the expansion
tank (if installed).
Insufficient heat in some
places in the heating system.
The flow is too low. Increase the head (setpoint) and/or
change over to constant pressure.
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