4
Model BDF • Belt Drive Duct Fan
®
Pre Start-Up Checks
1. Check all fasteners for tightness. The wheel
should rotate freely and not rub on the fan
panel venturi. Turn the fan on momentarily to
check for unusual vibration or noise. Do not
run the fan more than a few seconds without
being connected to the system for which it was
designed. Motor overloading and burnout may
result from lack of system static pressure.
2. Inlet and discharge collars are provided for duct
connection. The inlet panel is removable for
attaching optional filter box accessory.
3.
Wheel Rotation:
Direction of wheel rotation
is critical. Check wheel rotation by momentarily
energizing the unit. Improper rotation will result
in reduced airflow and pressure capabilities.
Rotation is always in the same direction as
airflow at the outlet. See housing and wheel
examples in figure 4.
4.
Vibration Isolators:
After fan is moved to
desired location, punch out the four knock-out
holes which are located on the unit top and
bottom panels. Assemble the brackets to the
unit according to the appropriate drawings
on page 3 and refer to respective parts list on
page 7. Make certain all connectors are tight
and that all washers are in.
5
If adjustments are made, it is very important
to check the pulleys for proper alignment.
Misaligned pulleys lead to excessive belt wear,
vibration, noise and power loss. (See figure 5)
6.
For all BDF Fans:
Belt tension can be
adjusted by loosening four fasteners (marked
“R”, figure
6
) on the drive frame. The motor plate
slides on the slotted adjusting arms (see figure
1
7). Belt tension should be adjusted to allow
1/64 inch of deflection per inch of belt span.
For example, a 15 inch belt span should have
15/64 inch (or about 1/4 inch) of deflection with
moderate thumb pressure at mid-point between
pulleys (See figure
7
). Overtightening will cause
excessive bearing wear and noise. Too little
tension will cause slippage at startup and
uneven wear.
Figure 5
Belt Span
Deflection = Belt Span
64
WRONG
WRONG
WRONG
CORRECT
G
C
lo
c
k
w
is
e
Belt Span
Deflection = Belt Span
64
WRONG
WRONG
WRONG
CORRECT
G
C
lo
c
k
w
is
e
Belt Span
Deflection = Belt Span
64
WRONG
WRONG
WRONG
CORRECT
G
C
lo
c
k
w
is
e
WARNING
Correct direction of wheel rotation is critical.
Reversed rotation will result in poor air
performance, motor overloading and possible
burnout.
Belt Span
Deflection =
Belt Span
64
Cl
o
ckwis
e
CORRECT
WRONG
WRONG
WRONG
Figure 7
AIRFLOW
RO
TA
T O
I N
AIRFLOW
RO
TA
T O
I N
AIRFLOW
RO
TA
T O
I N
AIRFLOW
RO
TA
T O
I N
Figure 4:
Wheel Rotation Guide
NOTE:
Identical
fasteners on
opposing
side must
also be
loosened.
Figure 6
R
