104
NOTE: While adjusting linkage, one damper must be fully open
and the other fully closed. Top and rear dampers are shipped with
both dampers in closed position. Loosen the swivel on the inter
-
connecting linkage bar and fully open rear damper, leaving top
damper closed. Retighten the swivel.
Certain damper combinations require that dual actuators or bell
-
crank linkages be field-provided when jack shafts are 90 degree
opposed. This may occur when there is a combination of end
dampers with either top or bottom dampers.
FIELD SUPPLIED AND INSTALLED ACTUATORS
If one or two actuators are used, they must be mounted to the out
-
door-air damper jackshaft. To properly set the connecting linkag
-
es, determine the rotation required to open the outdoor-air damper.
Ensure the actuator spring return fully closes the outdoor-air
damper.
If more than 2 actuators are used, they must be installed in equal
numbers on each jackshaft. To properly set these dampers, deter
-
mine the rotation required for each damper and mount the actua
-
tors so that the spring feature will open the return-air damper and
close the outdoor-air damper. Lock each damper actuator to the
jackshaft. Remove any factory-supplied connecting linkage be
-
tween the outdoor air and return-air dampers. Failure to do so will
damage the actuators. No additional linkages are required for
these applications.
Exhaust damper boxes are shipped with dampers in the closed
position.
All damper crankarms have 90 degrees travel from open to closed.
They may be adjusted to suit actuator location.
DO NOT mount damper actuators on the unit panels; actuators are
shaft mount only. See Table 26 on page 100 for operating torque
requirements.
Mixing Box Damper Actuators
The 39M mixing boxes can be supplied with direct mounted
damper actuators. Refer to Fig. 48 for typical actuator mounting.
Actuators are also available for field installation. See Field Sup
-
plied and Installed Actuators section above for more information.
Refer to Table 26 on page 100 for damper operating torque.
To ensure torque is transmitted equally to both damper sections,
actuator must be connected to the jackshaft that drives the inter
-
connecting linkage bar. Connection to any other shaft is not rec
-
ommended.
Vertical Draw-Thru Units
NOTE: Size 21-61 vertical units that exceed the 108-in. maximum
height or units with a vertical fan shipping split are shipped with
the fan out of its operating position, separate from the vertical coil
section. See Fig. 49.
The unit is secured to a wooden skid with lag screws. Remove
screws before lifting the unit.
Stacked Supply Fan, Return Fan and Exhaust
Box Sections
NOTE: Do not remove the fan spring isolator holddown bolts until
the section is installed on the coil section.
1. Rig the fan section using the lifting brackets and place it on
top of the coil section. See Fig. 49.
2. Secure the fan and coil sections together using the supplied
flat washer, the lock washer and the lock nut onto the stud.
See Fig. 50. Screw the base rail of the top unit to the top
frame rail of the bottom unit.
Stacked Units Turning Plenum
In a stacked unit configuration (one or multiple sections stacked
on top of one or multiple sections), the units are typically
connected by a turning plenum (Fig. 51). The upper turning
plenum must be sealed and attached to the lower turning plenum
with field-supplied gasketing and hardware. Suggested closed cell
gasketing is 0.25 in. x 1.50 in. (for example, McMaster 8694K94
or Grainger 6YLW0). Suggested hardware is
1
/
4
-14 self-drilling
screws spaced at a minimum of 12 in. apart. Clearance and
engagement holes must be drilled in the field through the base rail
into the top frame rail.
Fig. 48 —
Typical Mixing Box Actuator Mounting
Fig. 49 —
Positioning Fan Section
on Top of Coil Section
a39-4247
