15
Fig. 16 — Base Rail Split — Screws
Mixing Box
DAMPER ACTUATORS
The 39L mixing boxes are supplied 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. Refer to Fig. 18.
NOTE: If the unit is shipped with
Air
Manager™ controls, actua-
tor(s) are factory-supplied. Refer to Table 4.
To ensure torque is transmitted equally to both damper sections,
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. 17. See Fig. 19 for duct connection sizes.
NOTES:
1. Torque values are based on interconnected dampers driven by one
operator. For units with separate operators for each damper, calcu-
late torque as follows: Table values x .80 = torque per damper
section.
2. Damper shaft moves 90 degrees from open to closed position.
Fig. 17 — Mixing Box Ductwork Attachment
Table 3 — Mixing Box Damper Operating Torque
(in.-lb)
39L UNIT SIZE
TORQUE
03
20
06
20
08
26
10
29
12
33
15
41
18
52
21
56
25
76
AB 1/4-5/8 SCREWS
AB 1/4-3/4 SCREWS
LEGEND
MXB
—
Mixing Box