Grundfos CMBE - Pump Performance Unstable; Pump Runs Backwards when Switched Off

11.3 Pump performance is unstable
The pump performance is unstable. No lights on
Grundfos Eye.
TM063804
Cause Remedy
The pump inlet pressure
is too low.
• Check the inlet
conditions of the pump.
The inlet pipe is partly
blocked by impurities.
• Remove and clean
the inlet pipe.
Leakage in
the inlet pipe.
• Remove and repair
the inlet pipe.
Air in the inlet pipe or
the pump.
1. Vent the inlet pipe or
the pump.
2. Check the inlet
conditions of the pump.
11.4 Pump runs backwards when switched
off
The pump runs backwards when switched off. No
lights on Grundfos Eye.
TM063804
Cause Remedy
Leakage in
the inlet pipe.
• Remove and repair
the inlet pipe.
The non-return valve is
defective.
• Remove and clean,
repair or replace the
valve.
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English (GB)