25
Mixing Box Air Sensor
MIXING BOX MIXED AIR SENSOR BRACKET
ASSEMBLY — To assemble the mixed air sensor bracket
assembly to the mixing box, attach mixed air sensor to mixed
air sensor bracket. See Fig. 38.
MIXED AND OUTSIDE AIR SENSORS INSTALLATION
1. Remove access panel and filters as needed.
2. Place mixed air sensor assembly in airstream as shown in
Fig. 39.
3. Attach to top of unit with self drilling screws.
4. Drill or knockout
1
/
2
in. hole into top of mixing box close
to actuator as shown in Fig. 39.
5. Insert snap bushing in hole. Run wires inside unit, along
top of mixing box, between the filter rail and insulation,
and attach to mixed air sensor.
6. Place enthalpy sensor, shown in Fig. 40, in location suit-
able to meet manufacturer's requirements.
7. Connect all sensors to logic module per manufacturer's
instructions.
8. Test to ensure proper function.
9. Replace all parts and tape or fill any holes or gaps made.
Mixing Box —
To install mixing box:
1. Insert rear return duct flanges of unit into opening of
mixing box.
2. Ensure all unit flanges are inside the opening of the mix-
ing box and screw a minimum of three screws into each
of the unit’s four flanges using self-drilling screws.
3. The mixing box should now hang freely from the unit.
NOTE: Hanging brackets (shipped loose), as shown in
Fig. 41, are recommended for 39SH and 39SM unit sizes
07 and above. To install brackets, place in approximate
location and use self-drilling screws to attach to mixing
box. Brackets are sized to allow hanging from Unistrut.
Unistrut should be cut to the length one to two inches
shorter than the width of the mixing box to avoid any in-
terference with the damper linkages.
4. Remove unit filters from unit before start-up.
MIXING BOX LINKAGE INSTALLATION (39SH Unit
Sizes 00-03) — To install the mixing box linkage assembly
(sizes 00-03):
1. Check for correct number of parts:
1 – Linkage rod
2 – Linkage arms
2 – Swivel joints
NOTE: A
7
/
16
in. box end wrench and/or socket will be
needed for linkage installation.
2. Attach actuator (optional item) to unit with actuator
mounting hardware included with actuator. Actuator
should be mounted on damper rod 1 (DR1) as shown in
Fig. 42.
3. Orientate actuator to avoid interference with linkage
assembly.
4. Ensure dampers are fully closed or open depending on
application, and secure actuator to shaft. Actuator should
open and close dampers fully. Adjust actuator as needed.
Fig. 39 — Mixed Air Sensor Installation
MIXED
AIR SENSOR
ASSEMBLY
HOLE
LOCATION
a39-4111
Fig. 41 — Installing Mixing Box
MIXING
BOX
HANGING
BRACKETS
(1 in. DIA.)
UNIT FILTER
ACCESS DOOR
39SH
UNIT
a39-4113
Fig. 38 — Mixed Air Sensor Bracket
a39-4110
Fig. 40 — Enthalpy Sensor
a39-4112
