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Intake hood damper (0 to 100% outside air)
Units requiring 100% outside air are provided with a rain hood
and dampers which may be controlled by a single actuator.
The actuator provides two-position control for opening the
dampers fully during unit operation and closing the dampers
during the off cycle. No unit mounted exhaust dampers are
provided.
Figure 18a.
Figure 18b.
Shaft, .500 Dia.
x 1.50 Long
3.00
.25
90
°
Stroke
OA
Closed
OA
Open
Note: For good airflow control, adjust linkages so damper
blades do not open beyond 70 degrees. Opening a damper
blade beyond 70 degrees has little effect on its airflow.
Do not “overclose” low leak damper blades. The edge seal
should just lightly contact the adjoining blade. The blades will
lock up if they are closed so far the seal goes over center.
.75
Figure 19.
Intake hood damper (0 to 30% outside air)
These dampers are intended to remain at a fixed position
during unit operation, providing fresh air quantities from 0 to
30% of the total system airflow, depending on the damper
setting. This setting is made at the linkage rod on units with
manually adjustable linkages.
On units provided with MicroTech controls, the damper
position may be set at the controller keypad. During unit
operation, the two-position actuator drives the damper to the
position set on the keypad. During the off cycle, the damper
is automatically closed.
No unit mounted exhaust dampers are provided with this
option.
Airflow
f
3.15" (80 mm)
Max. Stroke of
Damper Linkage Bar
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