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12
OPTIONAL DURABLADE ECONOMIZER — The option-
al economizer hood assembly is packaged and shipped in the fil-
ter section. Damper blades and control boards are installed at the
factory and the economizer is shipped in the vertical discharge
position.
NOTE: Horizontal discharge block-off plate is shipped with
the air hood package. If unit is to be used for vertical discharge
application, discard this plate.
Assembly
1. Determine if ventilation air is required in building. If so,
determine the minimum amount to be supplied by each
unit and record quantity of ventilation air needed for use
in Step 8.
2. Remove filter access panel by raising panel and swinging
panel outward. Panel is now disengaged from track and
can be removed. No tools are required to remove filter ac-
cess panel. Remove outdoor-air opening panel. Save pan-
els and screws. See Fig. 17. Remove optional economizer
and outdoor-air damper hood package from filter section.
3. Assemble outdoor-air hood top and side plates as shown
in Fig. 18. Install seal strips on hood top and sides. Put
aside screen retainer and retainer screw for later assem-
bly. Do not attach hood to unit at this time.
4. On 012 and 014 units, install vertical discharge block-off
plate on right side over return air duct opening. See
Fig. 19.
5. a. Slide economizer into unit and secure with screws.
See Fig. 20.
NOTE: Be sure to engage rear economizer flange under tabs at
rear of vertical return-air opening.
b.
Remove screw and discard from barometric relief
damper. See Fig. 20.
6. To convert to horizontal discharge application:
a.
Rotate the economizer 90 degrees until the econo-
mizer motor faces the condenser section (see
Fig. 21).
b.
Rotate the barometric relief damper hinge
90 degrees. Barometric relief damper should open
vertically to operate properly.
c.
Install horizontal discharge block-off plate over
the opening on the access panel. (Block-off plate
MUST be installed before installing hood assem-
bly.) See Fig. 22.
7. Insert economizer plug into economizer harness. Remove
tape from barometric relief damper. See Fig. 20.
8. If ventilation air is not required, proceed to Step 9. If ven-
tilation air is required, determine the minimum position
setting for required airflow. See Fig. 23. Adjust minimum
position setting by loosening the screws on the position
setting bracket. See Fig. 24. Slide bracket until the top
screw is in the position determined by Fig. 23. Tighten
screws.
9. Remove tape from outdoor-air thermostat (OAT). Fasten
OAT to inside of hood using screws and speed clips pro-
vided. See Fig. 25. Make sure OAT terminals are posi-
tioned up.
10. Replace outdoor-air opening panel using screws from
Step 2. Replace filter access panel. Ensure the filter ac-
cess panel slides along the tracks and is securely engaged.
11. Fasten hood top and side plate assembly to outdoor-air
opening panel with screws provided.
12. Place knob supplied with economizer on OAT. See
Fig. 25. Set OAT for 1.7° C (3° F) below indoor room
thermostat setting. If accessory enthalpy control (EC) is
used in place of OAT, see instructions shipped with EC
for installation and adjustment. See Fig. 25.
13. Connect OAT per Fig. 26.
14. Slide outdoor-air inlet screens into screen track on hood
side plate. While holding screens in place, fasten screen
retainer to hood using screws provided.
NOTE: Refer to Fig. 27 for Durablade economizer barometric
relief damper characteristics.
1" (25 mm) OPEN
2" (51 mm)
3" (76 mm)
4.4" (1
12 mm)
0
2
4
6
8
10
12
OUTDOOR AIRFLOW (cfm x 100)
0
100
200
300
400
500
OUTDOOR AIRFLOW (L/s)
0.2
0.4
0.6
0.8
1.0
NEGA
TIVE PRESSURE (Pa)
0
50
100
150
200
250
NEGA
TIVE PRESSURE (in. wg)
Fig. 16 — Position Setting
OUTDOOR-AIR
OPENING PANEL
FILTER ACCESS
PANEL
Fig. 17 — Access Panel Locations