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13

11. Fault finding

* Or contact the nearest Grundfos company or 

service workshop.

12. 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 starting fault finding, switch off 
the power supply. Make sure that the 
power supply cannot be accidentally 
switched on.

Fault

Cause

Remedy

1.

The pump does 
not start.

a)

The fuses in the electric 
installation have burnt.

Replace the fuses. If the new fuses also burn, 
check the electric installation.

b)

The earth leakage circuit 
breaker or the 
voltage-operated circuit 
breaker has tripped.

Cut in the circuit breaker and check the electric 
installation.

2.

There is power on 
the pressure 
switch but not the 
pump.

a)

The power supply to the pump 
is disconnected after the 
pressure switch unit.

Check the cable connections.

b)

The pressure switch unit is 
defective.

Repair or replace the pressure switch unit. *

3.

The pump does 
not start when 
water is 
consumed.

a)

Too big difference in height 
between the pressure switch 
unit and the tapping point.

Adjust the cut-in pressure.

b)

The pressure switch unit is 
defective.

Repair or replace the pressure switch unit. *

4.

Frequent 
starts/stops.

a)

Leakage in the pipework.

Check and repair the pipework.

b)

The pressure tank has no 
precharge pressure, or the 
tank size is insufficient.

Check the tank precharge pressure, and 
recharge the tank, if necessary. See section 

7.

5.

The pump does 
not stop.

a)

The pressure switch unit is 
defective.

Repair or replace the pressure switch unit. *

6.

The motor cuts 
out during 
operation.

a)

The thermal switch in the 
motor has tripped due to 
overheating.

The thermal switch will cut in automatically 
when the motor has cooled sufficiently.
If the problem still persists, check these two 
possible causes:
• Impeller stuck.

Clean the pump.

• Motor defective.

Repair or replace the motor. *

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