Position The Opener - Chamberlain 3850 Owner's Manual

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.
ENGAGED
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.
Trolley
Release Arm
RELEASED
To prevent damage to garage door, rest garage door opener
rail on 2x4 placed on top section of door.
Rail
Door
11
2x4 is used to determine
the correct mounting height
from ceiling.
Header
Bracket
Top of Motor Unit
Top of Door
2x4 is used to determine
the correct mounting height
from ceiling.