Greenheck DFD Series Installation, Operation And Maintenance Manual page 36

Installation continued....
Figure 3: Mullion assembly for damper units 3 or 4 sections wide x 2 section high and pressures 6 in. wg or less
5) If the damper actuator is to be mounted out of the airstream, the extension pin should extend approximately 6
in. (152mm) beyond the frame. On jackshafted units, the jackshaft should extend through the jackshaft bearing
assembly approximately 6 in. (152mm) beyond the frame.
6) Individual damper sections, as well as entire multiple section assemblies must be completely square and free from
racking, twisting, or bending. Measure diagonally from upper corners to opposite lower corners of each section.
7) Damper blades, axles, and linkage must operate without binding. Before system operation, cycle dampers
after installation to assure proper operation. On multiple section assemblies, all sections should open and close
simultaneously.
Note: For vertical damper installation, blades must be horizontal. If vertical blades are needed, a vertical blade
damper is required (example: VCD-23V). These dampers are built to ensure the jamb seal does not get crushed.
4 VCD, FBH, and FBV Series