Carrier 39LB Installation, Mixing Box Damper Operating Torque In.-lb, 39L Unit Size Torque

INSTALLATION

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 2.

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. 8. For external mounting of actuators, drill or punch a hole in the exterior panel.

NOTE: If the unit is shipped with AirManager™ controls, actuator(s) are factory-supplied. Refer to Table. 3.

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. 9. See Fig. 10 for duct connection sizes.

Table 2 — 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

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.

Condensate Drain — Install a trapped condensate drain line at unit drain connection. Use 1-in. standard pipe.

Measure maximum design negative static pressure up- stream from the fan. Referring to Fig. 7, height “H” must be equal to or larger than negative static pressure at design operat- ing conditions. Prime enough water in trap to prevent losing seal (Differential 1). When the fan starts, Differential 2 is equal to the maximum negative static pressure.

Provide freeze-up protection as required.

MXB — Mixing Box

Fig. 9 — Mixing Box Ductwork Attachment

Fig. 8 — Typical Mixing Box Actuator Mounting

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