AUTOMATIC OPPOSED BLADE DAMPERS (AOBD)
5 68-0246
IMPORTANT
When installing damper in horizontal air duct, be 
sure to mount the electric actuator and drive linkage 
toward the top of the air duct. See Fig. 6.
Fig. 6. Correct damper mounting position.
INSTALLING AUTOMATIC OPPOSED BLADE DAMPERS (AOBD), SEE 
FIG. 7)
1.
Be sure the AOBD is correctl
 sized to the air duct.
2.
Select an AOBD location that is at least three feet from 
the furnace plenum.
3.
Cut a three-in. 
76 mm
 openin
 in one side of the air 
duct at the location selected. Be sure the openin
 is cut 
full
 to the top and bottom air duct seams.
4.
Slide the AOBD into the air duct. Be sure the electric 
actuator is mounted toward the top of the air duct.
5.
For small air duct sizes 
20 x 8 in. 18 x 10 in, 16 x 12 in. 
and smaller
, secure the AOBD mountin
 plate to the air 
duct with sheet metal screws provided.
6.
For lar
e air duct sizes 
20 x 8 in, 18 x 10 in., and 16 x 
12 in. and lar
er
, secure the mountin
 plate to the air 
duct with the sheet metal screws provided. Then secure 
the back of the AOBD to the air duct. If the back of the 
AOBD cannot be reached, install two mountin
 tracks. 
See Fi
. 8.
INSTALLING MULTIPLE DAMPERS AND DAMPER MOUNTING 
TRACKS
For air duct sizes lon
er than 30 in., use multiple dampers and 
install mountin
 tracks inside the air ducts. See Fi
. 8.
Fig. 7. Installing AOBD.
M2406A
INCORRECT
CORRECT
3 IN. (76 mm)
DUCT OPENING
1
1
2
2
DAMPER MOTOR ACTUATOR AND DRIVE LINKAGE MUST BE TOWARD 
TOP OF DUCT.
USE 1/4 IN. (6 mm) SHEET METAL SCREWS PROVIDED.
3
3
FOR LONGER DUCTS OR VERTICAL DUCT APPLICATIONS, SECURE 
BACK OF DUCT USING TWO SHEET METAL SCREWS.
M2275B