Grundfos UNILIFT AP35B, Installation And Operating Instructions Manual

Page: 11 / 204

English (GB)
11
7. Fault finding the product
Warning
Before starting any work on the product,
make sure that the power supply has been
switched off and that it cannot be
accidentally switched on.
Fault Cause Remedy
1. The motor does not
start. a) No power supply. Connect the power supply.
b) The pump was stopped by the level
switch.
Adjust or replace the level switch.
c) The fuses have blown. Replace the fuses.
d) The motor protection/thermal relay has
tripped. Wait until the motor protection
trips in again/reset the relay.
e) The impeller is blocked by impurities. Clean the impeller.
f) Short circuit in the cable or motor. Replace the defective part.
2. The motor protection/
thermal relay trips
after a short time of
operation. a) The liquid temperature is too high. Use another pump type.
b) Impeller blocked or partly blocked by
impurities.
Clean the pump.
c) Phase failure. Call an electrician.
d) Too low voltage. Call an electrician.
e) Overload setting of the motor-protective
circuit breaker too low.
Adjust the setting.
f) Incorrect direction of rotation. See
section
3.1 Checking the direction of
rotation .
Reverse the direction of rotation.
3. The pump runs
constantly or gives
too little water. a) The pump is partly blocked by
impurities.
Clean the pump.
b) The outlet pipe or valve is partly
blocked by impurities.
Clean the outlet pipe.
c) The impeller is not properly fixed to the
shaft.
Tighten the impeller.
d) Incorrect direction of rotation. See
section
3.1 Checking the direction of
rotation .
Reverse the direction of rotation.
e) Incorrect setting of level switch. Adjust the level switch.
f) The pump is too small for the
application.
Replace the pump.
g) The impeller is worn. Replace the impeller.
4. The pump runs but
gives no water. a) The pump is blocked by impurities. Clean the pump.
b) The outlet pipe or non-return valve is
blocked by impurities.
Clean the outlet pipe.
c) The impeller is not properly fixed to the
shaft.
Tighten the impeller.
d) Air in pump. Vent the pump and the outlet
pipe.
e) The liquid level is too low. The pump
inlet is not completely submerged in the
pumped liquid.
Submerge the pump in the liquid
or adjust the level switch.
f) The level switch does not move freely. Make the level switch move
freely.