Chamberlain HD210C Manuel page 2

Preparation
Safety Symbol and Signal Word Review
This garage door opener has been designed and tested to offer safe service provided it is installed,
operated, maintained and tested in strict accordance with the instructions and warnings contained in this
manual.
When you see these Safety Symbols and Signal Words on the following pages, they will alert you to the
possibility of serious injury or death if you do not comply with the warnings that accompany them. The
hazard may come from something mechanical or from electric shock. Read the warnings carefully.
When you see this Signal Word on the following pages, it will alert you to the possibility of damage to
your garage door and/or the garage door opener if you do not comply with the cautionary statements that
accompany it. Read them carefully.
Unattended Operation
Any device or feature that allows the door to close without being in the line of sight of the door is
considered unattended close. Devices that allow unattended operation are to be used ONLY with
sectional doors.
Mechanical
Electrical
Check the Door
To prevent possible SERIOUS INJURY or DEATH:
ALWAYS call a trained door systems technician if garage door binds, sticks, or is out of balance.
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An unbalanced garage door may NOT reverse when required.
NEVER try to loosen, move or adjust garage door, door springs, cables, pulleys, brackets or their
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hardware, ALL of which are under EXTREME tension.
Disable ALL locks and remove ALL ropes connected to garage door BEFORE installation and
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operating garage door opener to avoid entanglement.
DO NOT install on a one-piece door if using devices or features providing unattended close.
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Unattended devices and features are to be used ONLY with sectional doors.
To prevent damage to garage door and opener:
ALWAYS disable locks BEFORE installing and operating the opener.
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ONLY operate garage door opener at 120 V, 60 Hz to avoid malfunction and damage.
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Before you begin:
1. Disable locks and remove any ropes connected to the garage door.
2. Lift the door halfway up. Release the door. If balanced, it should stay
in place, supported entirely by its springs.
3. Raise and lower the door to check for binding or sticking. If your door
binds, sticks, or is out of balance, call a trained door systems
technician.
4. Check the seal on the bottom of the door. Any gap between the floor
and the bottom of the door must not exceed 1/4 inch (6 mm).
Otherwise, the safety reversal system may not work properly.
5. The opener should be installed above the center of the door. If there
is a torsion spring or center bearing plate in the way of the header
bracket, it may be installed within 4 feet (1.2 m) to the left or right of
the door center. See page 11.
1
Torsion Extension
OR
Spring Spring