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Mixing Box
DAMPER ACTUATORS — The 39L mixing boxes are sup-
plied with low leak dampers and blade and edge seals. Damper
operating torques are shown in Table 3.
The actuator and mounting brackets are field supplied and
may be mounted inside or outside the unit. A typical inside
mounting bracket is shown in Fig. 17. For external mounting of
actuators, drill or punch a hole in the exterior panel.
NOTE: If the unit is shipped with
Air
Manager™ controls,
actuator(s) are factory-supplied. Refer to Table 4.
To ensure torque is transmitted equally to both damper sec-
tions, actuator must be connected to the 1-in. hollow jackshaft
that drives the interconnecting linkage bar. Connection to any
other shaft is not recommended.
DUCTWORK ATTACHMENT — Ductwork should be
flanged out and attached to the mixing box panels as shown in
Fig. 18. See Fig. 19 for duct connection sizes.
Table 3 — Mixing Box Damper Operating Torque
(in.-lb)
NOTES:
1. Torque values are based on interconnected dampers driven by
one operator. For units with separate operators for each
damper, calculate torque as follows: Table values x .80 = torque
per damper section.
2. Damper shaft moves 90 degrees from open to closed position.
39L UNIT SIZE
TORQUE
03
20
06
20
08
26
10
29
12
33
15
41
18
52
21
56
25
76
MXB — Mixing Box
Fig. 18 — Mixing Box Ductwork Attachment
Fig. 17 — Typical Mixing Box Actuator Mounting