Chamberlain 1200 - Manual (Page 16)

Installation Step 4
Position the Opener
Follow instructions which apply to your door type
as illustrated. To prevent damage to steel, aluminum,
fiberglass or glass panel doors, do not rest the
opener on the door without using a 2x4.
SECTIONAL Door & ONE-PIECE Door with Track
T-rail 2x4
Door
Stepladder
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 opener
to the same distance as the door from the floor (it
will be at a slight angle as shown).
• The top of the door should be level with the top of
the opener. Do not position the opener more than
2" above this point.
Top of Opener
Header
Bracket
Stepladder
Top of Door
16
CAUTION
A 2x4 laid flat is convenient for setting an ideal
door-to-T-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 T-rail.
• If the top panel hits the trolley when you raise
the door, pull down on the trolley release arm
to disconnect inner and outer sections. The
trolley can remain disconnected until Step 12
is completed.
Trolley
Trolley
Release Arm