5
Model H-G/H-GB Centrifugal Roof Exhaust Fan
WARNING
Correct direction of wheel rotation is critical. Reversed
rotation will result in poor air performance, motor
overloading and possible burnout.
WARNING
The fan has been checked for mechanical noises at the
factory prior to shipment. If mechanical noise should
develop, suggested corrective actions are offered in
the Troubleshooting section.
IMPORTANT
Over tightening will cause excessive bearing wear and
noise. Too little tension will cause slippage at startup
and uneven wear.
Model H-GB
Pre-Starting Belt Tension Checks
8. Always loosen tension enough to install belts without
stretching, see figure 11.
9. For units with two groove pulleys, adjust so the
tension is equal in both belts.
10. 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 12.
Fig.
Wheel Overlap and Gap Dimensions
Fig. 9
G
H
Model
G - Overlap in (mm)
H - Gap in (mm)
H-G 060-095
–
3
⁄
32
(2)
H-G 101-180
–
1
⁄
4
(6)
H-GB 071-161
1
⁄
4
(6)
–
H-GB 180-240
3
⁄
8
(10)
–
H-GB 260-300
1
⁄
2
(13)
–
Do not force belt(s). Forcing the
belt(s) will break the cords and
cause belt failure
.
Belts
Fig.
Slack
Side
Deflection
Fig. 4a
Fig. 4b
11. Belt tension can be adjusted by loosening four
fasteners on the drive frame, see figure 13. The
motor plate slides on the slotted adjusting arms and
drive frame angles in the same manner.
12a. Sizes 071-161: Belts should be tensioned just
enough to prevent slippage at full load.
Note: Belts should have a slight bow on the slack
side while running at full load (see figure 14a).
12b. Sizes 180-300: Belt tension should be adjusted to
allow
1
⁄
64
in
(0.397 mm)
of deflection per inch of belt
span. For example, a 15 in
(381 mm)
belt span should
have
15
⁄
64
in
(0.234 mm)
(or about
1
⁄
4
in
(6 mm)
) of
deflection with moderate thumb pressure at mid-point
between pulleys (see figure 14b).
13. The adjustable motor pulley is factory set for the
RPM specified. Speed can be increased by closing
or decreased by opening the adjustable motor pulley.
Fasteners
*Identical fasteners on
opposing side must also be
loosened.
Fig. 3
(4) *Fasteners
Wheel Rotation
H-G 060-3
H-G 4-80
All H-GB Models
Fig. 0
Clockwise
Airflow
Counterclockwise
Airflow
Clockwise
Airflow
Counterclockwise
Airflow
