Fault description
Cause
Remedy
Personnel
Airflow is not cor-
rect
The duct system’s pres-
sure losses are higher
than expected / calcu-
lated
Increase the fan speed (note: do not exceed
the motor limit rating or the max. fan speed)
Is the operating point in the unstable range?
Reconfigure and replace the fan
Open the bypass
Reduce pressure losses in the duct
Instructed person
Dampers or grilles in
the system are closed
Open the dampers or grilles
Instructed person
An object is obstructing
the airflow in the duct
Clean the duct / remove the obstruction
Instructed person
Vane controls are (par-
tially) closed
Open the vane controls
Instructed person
Filter is dirty
Clean or replace the filter
Instructed person
Fan is pumping
Fan is working in an
unfavourable character-
istic curve range
Reduce the system resistances.
Instructed person
Increased vibra-
tions
Impeller imbalance due
to deposits
Please note that the system, consisting of the
impeller and motor, always has a residual
imbalance, even if all of the components are
balanced!
Clean and rebalance the impeller
Instructed person
Vibration isolators are
assembled or posi-
tioned incorrectly
Incorrectly selected vibration isolators can
result in destruction of the fan!
Configure and assemble vibration isolators cor-
rectly
Instructed person
Vibration isolators are
the wrong size
Replace the vibration isolators
Instructed person
Air noises
Direction of rotation is
incorrect
Change the direction of rotation by switching
two phases on the terminals
Skilled qualified
electrician
Pulsating volume flow
rate
Have the standard rules for the installation of
fans been complied with? See Chapter
12 ‘Installation and assembly recommenda-
tions for axial fans’ on page 49
Increase the cross sections to improve the pas-
sage of air
Install baffle plates
Instructed person
Is the operating point in an unstable area?
Implement measures to reduce the overall
pressure loss
Instructed person
Mechanical noises
Contamination on the
casing or impeller
Clean the casing / impeller
Instructed person
Impeller is grinding
Caused by a misaligned connection duct due to
deformation of the casing, for example.
Check the impeller gap
Realign the fan
Instructed person
Faults
List of faults
Axial fans AXO/BVAXO; AXN/BVAXN; ZAXN/BVZAXN
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