Howden ELF - Page 21

Howden 24-07.030r04 21/25
E-series Axial Flow Cooling Fans
Service Manual
Problem
Possible cause
Possible solution
Power absorption (too)
high. (2)
Static pressure higher than
specified.
Decrease blade angle.
Clean system air-cooler
bundles or cooling tower
fill.
Air temperature lower than
design air temperature.
Check performance
against current air tem-
perature.
Airflow too high.
Decrease blade angle.
Blade angle too large.
Set blade angle according
fan selection details.
Transmission out of order.
Check transmission.
Impeller is rubbing against
fan casing.
Bolting of drive-train con-
nection, support structure
or fan housing is not tight.
Tighten all bolts.
Impeller not centred.
Centre the impeller.
Tip clearance too small.
Decrease impeller diame-
ter by placing nylon rings
between lower clamping
pieces and blade stem
collars.
Fan casing too weak.
Stiffen fan casing.
Vibration level high. (1)
Imbalance of impeller.
Check if position of fan
blades is according to in-
struction.
Lack of stiffness in support
structure.
Reinforce support struc-
ture.
Bolting of drive-train con-
nection or fan housing is
not tight.
Tighten all bolts.
Drive alignment incorrect.
Realign.
Driver bearing damage.
Repair or replace.
Drainage holes are
blocked.
Open the drainage holes.
Blade is not flush against
lower clamping piece.
Release U-bolts, pull the
blade outwards and re-
tighten the U-bolts to the
correct torque.
Blade angle(s) not within
±0.5° tolerance.
Re-set the blade angles.