Troubleshooting
Guide

TWISTED FRAME

• If light lines are observed only along half of the blade length, square up the position of the top frame member, relative to the bottom frame, by pivoting the top frame member either in or out.
• A small movement in one of these two directions could seal light lines, by eliminating frame distortion caused by torque being applied to an unsecured damper.

STRETCHED FRAME

• If light lines are observed between the side frame members and the blade ends of a backdraft damper, especially near the center line, verify measurements across the damper at the top, center, and bottom.
• If the measurements should vary by more than 1/16” (2 mm), readjust the side mounting angles to bring the side frame members to the correct dimension, thus matching top and bottom dimensions.
• If light lines disappear, ensure that these matching dimensions are retained when fastening mounting angles during installation, and that blades move freely following installation.

RACKED FRAME

• If light lines appear only near the top and bottom, on opposite sides of the backdraft damper, between the side frame members and the blade ends of a damper, verify square positioning with a tape measure and adjust if required
• If the blades of the backdraft damper catch on the one side of the jamb seal, this is also an indication that the frame may be skewed.
• Move the top frame member either left or right to square up the damper. Light lines should disappear.

COMPRESSED FRAME

• If the backdraft damper is hard to operate by hand, verify that frame sides are not squeezed in or twisted.
• In either case, bearing life could be sharply reduced.
• Verify that frame sides are parallel by measuring across the damper at the top, center, and bottom.
• Also verify that dimensions on both sides of the damper are equal.

DISTORTED FRAME

• If light appears only between the last blade and the top or bottom of the damper frame, it may be due to the top or bottom frame member being distorted (twisted) when fastened to the duct work.
• Ensure that the top or bottom frame members are not distorted, by loosening fasteners and shimming the frame, if required.