Xylem Lowara e-LNE series Installations- Betriebs Und Wartungshandbuch Seite 25

7.5 The pump unit runs but delivers too
little or no liquid
Cause
Motor turns in the wrong
direction
Incorrect priming (there are
air bubbles in the suction
pipe or in the pump unit)
Cavitation
Check valve locked in closed
or partially closed position
Foot check valve locked in
closed or partially closed
position
Flap valve damaged, worn or
faulty (models LNTE and
LNTS)
Delivery pipe throttled
Piping and/or pump unit
clogged
7.6 The pump unit turns the other way
when turned off
Cause
Check valve faulty
Foot check valve faulty
Flap valve damaged, worn or faulty
(models LNTE and LNTS)
7.7 The pump unit produces excessive
noise and/or vibrations
Cause
Cavitation
Unsuitable anchoring to
the ground
Resonance
Anti-vibration joints not
installed
Foreign bodies in the
pump unit
Motor bearings worn or
faulty
The pump unit does not
turn freely due to a
mechanical fault
Motor turns in the wrong Check the direction of
Remedy
Check the direction of
rotation and change it if
necessary
Repeat the priming
procedure
Increase the NPSH
available in the system
Replace the check
valve
Replace the foot valve
Replace the flap valve
Remove the throttling
Remove the clogging
Remedy
Replace the
check valve
Replace the foot
valve
Replace the flap
valve
Remedy
Increase the NPSH
available in the system
Check the anchoring to the
ground
Check the installation
Install anti-vibration joints on
the suction and delivery
lines of the pump unit
Remove the foreign bodies
Replace the motor bearings
Send the pump unit to an
authorised workshop for
testing
direction
7.8 The pump starts up too frequently
(automatic start/stop)
Cause
Incorrect priming (there are
air bubbles in the suction pipe
or in the pump unit)
Check valve locked in closed
or partially closed position
Foot check valve locked in
closed or partially closed
position
Flap valve damaged, worn or
faulty (models LNTE and
LNTS)
Starter (pressure switch,
sensor, etc.) set incorrectly, or
faulty
Expansion vessel
 no pre-charge, or
 undersized, or
 not installed
Pump unit oversized
7.9 The pump unit never stops
(automatic start/stop)
Cause
The required flow rate is
greater than the one
expected
Delivery pipe leaking
Motor turns in the wrong
direction
Pipes, valves or filter
clogged with impurities
Starter (pressure switch,
sensor, etc.) set incorrectly,
or faulty
The pump unit runs but
delivers too little or no
liquid
en - Original instructions
rotation and change it if
necessary
Remedy
Repeat the priming
procedure
Replace the check
valve
Replace the foot valve
Replace the flap valve
Adjust or replace the
starter
 Pre-charge the
expansion vessel,
or
 replace the
expansion vessel
with another
suitable one, or
 install an expansion
vessel
Contact Xylem or the
Authorised Distributor
Remedy
Reduce the required flow
rate
Eliminate the leaks
Check the direction of
rotation and change it if
necessary
Remove the impurities
Adjust or replace the
starter
See Par. 7.5
25