Fault Finding The Product; The Pump Does Not Start; The Pump Does Not Stop; The Pump Starts And Stops Randomly - Grundfos UNOLIFT Installation And Operating Instructions Manual

12. Fault finding the product

WARNING
Biological hazard
Death or serious personal injury
‐
Wear protective gloves, close the
isolating valves and drain the tank
before you start any work on the tank.

12.1 The pump does not start.

Cause
The float switch is blocked in low position.
The pump cable is defective.
Related information
7.1 Setting the start levels

12.2 The pump does not stop.

Cause
The float switch is blocked in high position.
Related information
7.1 Setting the start levels

12.3 The pump starts and stops randomly.

Cause
The float switch is not set properly.
The level sensor tube is not fixed properly in the tank
and is moving up as the liquid rises. The sensor
receives wrong signals.
The float switch cannot move freely because the
pump has moved.
Related information
3.12 Installing the pump
3.13.2 Assembling the pump connecting pipes
7.1 Setting the start levels

12.4 The tank is not emptying although the pump is running.

Cause
There is an airlock in the pump impeller. The pump
cannot build up pressure.
34
For faults indicated by alarms and related to the
controller, see the installation and operating
instructions of the controller.
For faults related to the pumps, see the installation
and operating instructions of the pumps.
Remedy
1. Make sure that the float switch can move freely.
2. It may be necessary to adjust the cable length. See
section Setting the start levels.
Repair or replace the cable.
Remedy
1. Make sure that the float switch can move freely.
2. It may be necessary to adjust the cable length. See
section Setting the start levels.
Remedy
Adjust the cable length of the float switch. See section
Setting the start levels.
Fix the tube to the tank. See fig. 13.
Position the pump according to fig. Correct position of
UNILIFT CC and KP pumps or Correct position of
UNILIFT APB pumps.
Remedy
Drill a hole of maximum 6 mm in the connecting pipes in
the tank. The air is pushed out when the pump starts,
and the pump builds up pressure. The pressure loss
due to the hole is negligible.