Grundfos CR 95 Installation And Operating Instructions Manual page 21

Fault
5. The pump
performance is not
constant.
6. The pump runs, but
gives no water.
7. The pump runs
backwards when
switched off.
8. Leakage in the shaft
seal.
9. Noise.
Cause
a) The pump inlet pressure is too low
(cavitation).
b) The inlet pipe or pump is partly
blocked by impurities.
c) The pump draws in air.
a) The inlet pipe or pump is blocked by
impurities.
b) The foot or non-return valve is
blocked in closed position.
c) There is a leakage in the inlet pipe.
d) There is air in the inlet pipe or pump.
e) The motor runs in the wrong direction
of rotation.
a) There is a leakage in the inlet pipe.
b) The foot or non-return valve is
defective.
a) The shaft seal is defective.
a) Cavitation.
b) The pump does not rotate freely due
to frictional resistance as a result of
incorrect pump shaft position.
c) Frequency converter operation.
Remedy
Check the inlet conditions.
Clean the inlet pipe or pump.
Check the inlet conditions.
Clean the inlet pipe or pump.
Repair the foot or non-return valve.
Repair the inlet pipe.
Check the inlet conditions.
Change the direction of rotation of
the motor.
Repair the inlet pipe.
Repair the foot or non-return valve.
Replace the shaft seal.
Check the inlet conditions.
Adjust the pump shaft as described
in the service documentation. See
section 6.2 Service documentation.
See the instructions for the motor
which are supplied with the pump.
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