Chamberlain 3255-2 1/2 HP - Manual (Page 4)

required. You may find it helpful to refer back to this page
and the accompanying illustrations as you proceed with
the installation of your opener.
FINISHED CEILING
Support bracket
& fastening
hardware is required.
See page 12.
Slack in chain tension
is normal when
garage door is closed.
Safety
Reversing Sensor
Header
Wall
Access
Door
Safety
Reversing Sensor
Gap between floor and bottom of
door must not exceed 1/4" (6 mm).
Wall-
mounted
Door
Control
Motor Unit
ONE-PIECE DOOR WITHOUT TRACK
4
Planning
Identify the type and height of your garage door. Survey
your garage area to see if any of the conditions below
apply to your installation. Additional materials may be
Access
Door
Safety
Reversing Sensor
Safety
Reversing Sensor
Slack in chain tension is normal when
garage door is closed.
Gap between floor
and bottom of door
must not exceed 1/4" (6 mm).
ONE-PIECE DOOR WITH TRACK
Safety Reversing Sensor
Horizontal and vertical reinforcement
is needed for lightweight garage doors
(fiberglass, steel, aluminum,
door with glass panels, etc.).
See page 19 for details.
— — — — — — — —
Header Wall
Safety
Reversing
Sensor
Gap between floor and bottom of door
must not exceed 1/4" (6 mm).
Extension Spring
Torsion Spring
Access Door
OR
Slack in chain tension
is normal when
garage door is closed.
Wall-
mounted
Door
Control
Motor Unit
FINISHED CEILING
Support bracket &
fastening hardware
is required.
See page 12.
Vertical Centerline
of Garage Door
SECTIONAL DOOR INSTALLATION