Reznor CAUA Option - Installation - Mixing Box Installation - Manual (Page 3)

Form I-CAUA-MB, P/N170640R2, Page 3
Depending on the installation, the cover may be in the correct position or it may need
to be moved. If the cover needs moved, remove the screws, position the cover over
the return air opening that will not be used, and attach using the same screws.
Installation NOTE: Depending on which return air opening is being covered, you may
want to wait to re-attach the cover after the mixing box is attached in Step 4.
4. Attach the Mixing Box
On the rear of the heater, remove the row of screws along the bottom (save the
screws). Position the mixing box against the rear of the heater. If installing a mixing
box with two dampers, remove one or both access panels on the ends of the box.
If only one damper, reach through the return air opening or remove end panel(s).
Reaching inside the mixing box, replace the screws attaching the bottom edge of the
mixing box to the heater.
Using the holes drilled in Step 2, attach both sides and across the top with the sheet-
metal screws provided.
5. Adjust the Damper Linkage - Applies to Mixing Boxes with both
Outside & Return Air Dampers (GA4, GA5, GA6, GA7, GA8, GA9)
Both dampers are closed for shipping. The linkage for the return air damper must be
adjusted prior to use. Follow instructions to adjust damper linkage.
1) Remove the access panel on the end of the mixing box where the damper
controls are located.
2) Loosen the setscrew on the return air damper rod at the damper arm.
3) Manually open the return air dampers. While the dampers are opening, the
damper rod and arm will automatically move to its correct position.
4) Tighten the setscrew.
5) Replace the end panel.
6. Connect the Damper Motor Wires
Wiring depends on the motor and control options selected. See explanation of damper
controls on page 4.
Wiring Instructions:
1) Remove the door panel on the front of the heater. Run the wires from the
damper motor into the heater cabinet, up past the side of the burner box (the
same side as the blower motor wires), and into the control compartment.
2) Refer to the wiring diagram with the heater and attach the wires to the
terminals indicated.
3) Replace the heater door panel.
7. I nstallation of the optional mixing box is complete. Follow the instructions in the
heater installation manual to complete the installation of your heater.
Attach the outside air ductwork to the duct flange on the outside air inlet of the mixing
box. If the system includes return air ductwork, attach it to the duct flange on the return
air inlet. To reduce noise transmission, use of a flexible duct boot to attach ductwork is
recommended. Ductwork must be supported; do not rely on the mixing box to support
the ductwork.
On startup, check for proper operation of the damper motor and controls.
Damper Controls -
In all cases when the
unit shuts down, the
outside air damper
closes.
Option Description
Damper Motors (Actuators)
GB2 2-position damper motor
GB3 Modulating damper motor
GB4 Modulating damper motor for use with proportional enthalpy control only
Control Options (Cause motor to operate damper.)
GC1A Potentiometer on mixing box
GC1B Remotely located potentiometer
GC3A Mixed air temperature controller, heating only
GC3B Dual setpoint modulating enthalpy control for heating & cooling, w/GB4 only
GC3C 2-position enthalpy control to use w/2-position damper motor, cooling only
GC4
Senses return air temperature to delay opening of outside air damper
providing warm up or cool down time