Chromalox SDRA-30-43 Installation And Operation Instructions Manual page 5

Accessories
Adjustable Damper and Duct Adapter
Rear of
Heater
1/4-20 Wing nut
Provided with
AD-16
Fan Speed Adjustments
Changing the Pitch Diameter of the Sheaves:
1. Tools required: 5/32" allen wrench, 3/8" nut driver, 9/16"
box wrench and a medium size phillips screwdriver.
2. Remove the lower belt cover by removing the (5) sheet
metal screws.
3. Remove the rear grille by removing the (4) 1/4" bolts and
nuts.
4. Remove the belt cover inside the blower by removing the
(4) sheet metal screws.
5. Loosen the (4) bolts, (2) on each side. See Fig. 1.
3/8" Bolts
Figure 1
Adjustable
Damper
6. Loosen the (2) motor tension lock nuts and the fan belt
tension adjusting bolts. See Fig.2
Lock Nuts
5
Front of
Heater
Duct
Adapter
Fan belt tension
adjusting bolts
3/8" Bolts
Figure 2