Fault Finding Chart - Grundfos MQ Serie Notice D'installation Et D'entretien

14. Fault finding chart

Fault
1. The pump does
not start.
2. The pump does
not stop.
3. The pump cuts out
during operation.
4. The pump starts
and stops too
frequently.
5. The pump gives
electric shocks.
6. The pump starts
when no water is
consumed.
If the pump does not start when the fault has been corrected, contact your pump supplier or Grundfos for
further information.
Cause
a) Insufficient water.
b) Overheating due to excessive liquid
temperature (above +95 °F/+35 °C).
c) Overheating due to seized-up/
choked-up pump.
d) Too low or too high supply voltage.
e) No electricity supply.
f) No water consumption.
g) Shaft is blocked.
h) Pump is in alarm condition.
a) Existing pipework is leaking or
defective.
b) Non-return valve is blocked or
missing.
a) Dry running.
b) Overheating due to excessive liquid
temperature (above +95 °F/+35 °C).
c) Overheating caused by:
- high ambient temperature
(> 113 °F/45 °C)
- overloaded motor
- seized-up motor/pump.
d) Too low supply voltage.
a) Leakage in suction pipe or air in
water.
b) Too low or too high pressure in
pressure tank.
a) Defective ground connection.
a) Internal non-return valve is
defective, or the existing pipework is
leaking or defective.
Remedy
Check the water supply/suction pipe.
Supply cold liquid to the pump.
Contact your pump supplier.
Check the supply voltage and correct the
fault, if possible.
Connect the electricity supply.
Open a tap. Check that the height
between the top point of the discharge
pipe and the pump does not exceed 50 ft.
Rotate the shaft as described in 10.2
Reset the pump by means of the on/off
button. See point 2 in the table of section
9.1 Control panel.
Repair the pipework.
Clean the valve or fit a new non-return
valve.
Check the water supply/suction pipe.
Supply cold liquid to the pump.
Contact your pump supplier.
Check the supply voltage and correct the
fault, if possible.
Check the water and the supply/suction
pipe.
Check the pressure in the pressure tank.
See section 6. Operating conditions.
Connect the ground connection to the
pump in accordance with local
regulations.
Clean the valve or fit a new one.
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