Help! My Pentair submersible pump is not pumping?

Is the pump silent, or does it run without pumping water?

These are different faults. If the motor does not run, air in the pump housing is not a sufficient explanation. Have the power supply checked and, with the power switched off, see whether the float switch can move freely. A damaged cable or an electrical fault must be repaired by a qualified professional.

Before any inspection or cleaning: disconnect the pump and any controls from the power supply and make sure nobody can switch them back on. A pump that has shut down thermally can restart by itself once it has cooled down.

Why can air stop the pump from pumping?

Trapped air can prevent water from reaching the impeller. Water left in a connected hose or discharge pipe can stop that air from escaping. The motor may then run while no water comes out of the hose.

Check these points first

1. Hose: for mobile use, let the discharge hose drain before you submerge the pump. Also check for kinks and blockages.
2. Water level: submerge the pump before you switch it on. Observe the minimum start water level stated in the manual; it differs per model.
3. Venting and check valve: check according to the manual whether air can escape and whether the valve is fitted correctly. Clean any vent opening according to the manufacturer's instructions.
4. Suction: check the strainer for dirt. Do not let the pump run dry while you look for the cause.

Venting differs per version

The current manual for the Jung Pumpen U3, U5 and U6 series describes automatic venting via the supplied 90° elbow. Older versions and other models may be built differently. So check the type plate and use the manual that belongs to your pump.

A vent hole may be required for certain versions or installations, but it is not a general solution for every Pentair/Jung Pumpen pump. First have it established whether this is prescribed for your pump. Flushing openings also serve a different purpose and must not be confused with vent openings.

View the manufacturer's manual for the current U3, U5 and U6 series (PDF). Check that the version described matches your pump.