Chamberlain 3850 - Manual (Page 11)

11
ONE-PIECE DOOR WITHOUT TRACK
• With the door fully open and parallel to the floor,
measure the distance from the floor to the top of the
door.
• Using a stepladder as a support, raise the top of the
opener to this height.
• The top of the door should be level with the top of the
motor unit. Do not position the opener more than
4" (10 cm) above this point.
INSTALLATION STEP 4
Position the Opener
Follow instructions which apply to your door type as
illustrated.
SECTIONAL DOOR OR ONE-PIECE DOOR WITH
TRACK
A 2x4 laid flat is convenient for setting an ideal door-to-rail
distance.
• Raise the opener onto a stepladder. You will need help
at this point if the ladder is not tall enough.
• Open the door all the way and place a 2x4 laid flat on
the top section beneath the rail.
• If the top section or panel hits the trolley when you raise
the door, pull down on the trolley release arm
to disconnect inner and outer sections. Slide the outer
trolley toward the motor unit. The trolley can remain
disconnected until Installation Step 12 is completed.
Rail
Door
2x4 is used to determine
the correct mounting height
from ceiling.
Trolley
Release Arm
ENGAGED RELEASED
To prevent damage to garage door, rest garage door opener
rail on 2x4 placed on top section of door.
Top of Motor Unit
Header
Bracket
Top of Door
2x4 is used to determine
the correct mounting height
from ceiling.
WARNING
CAUTION WARNING
WARNING