26
Step 7 — Make Outdoor-Air Inlet Adjustments
ECONOMIZER AND MIXED OUTDOOR AIR
DAMPER — Hoods are used on all units with economizer or
adjustable self-closing mixed outdoor air damper.
NOTE: If accessory power exhaust or barometric relief pack-
ages are being added to the unit, install power exhaust or baro-
metric relief before installing economizer hoods.
Economizer Hood Assembly — The economizer hood is
shipped in a package secured to the outside of the unit.
The hood assemblies must be field-assembled. The
50A4,A5,A8,A9 units are side supply and side return. The
return duct limits access to economizer filters from below.
The 50A020-050 units have two hoods on every unit. The
50A060 units have 3 hoods on every unit.
NOTE: Before assembly of the economizer hood, check along
the outer edges of the economizer assembly for any seal strip
protruding past the flanges. Trim the excess seal strip so that it
is flush with the economizer assembly flanges.
Perform the following procedure to assemble the economiz-
er hood.
1. Apply black seal strip (provided) to outside top-edge of
hood sides. Wrap seal strip over edge to cover top flange
(2 hood sides per hood assembly). Make sure seal strip
covers screw holes. See Fig. 24.
2. Add gray foam strip (provided) to cross members on bot-
tom tray. See Fig. 25.
3. Assemble hood sides, top, and cross member with gasket-
ed screws provided. See Fig. 26.
4. Attach speed clips (provided) to hood top. Engagement
section of the clip faces inside hood. See Fig. 27.
5. Apply black seal strip (provided) to mounting flanges
of hood sides being sure to cover mounting holes. See
Fig. 28.
6. Apply black seal strip (provided) to back of hood top
mounting flange. Seal strip of hood top mounting flange
must press tightly against seal strip of hood side mount-
ing flanges. See Fig. 28.
7. Attach gray foam strip (provided) to block-off baffle on
outer face of flange. See Fig. 29.
8. Remove the screws on each end and along top of the out-
door air opening of unit. Set hood assembly in place and
attach to unit using gasketed screws. See Fig. 30.
9. Locate and mount block-off baffle using 3 screws. See
10. Assemble bottom filter tracks side by side with the
mounting angle together. The filter track assemblies must
be installed with the flange and mounting angle pointing
11. Attach speed clips (provided) to hood side panels. En-
gagement section of clip faces up and towards the outside
of the hood side panels. Attach mounting angles to hood
with gasketed screws provided. See Fig. 35.
NOTE: Be sure the filters are installed with the airflow in
the correct direction.
12. Attach filter track under the hood assembly. See Fig. 36.
13. Attach black seal strip (provided) to filter cover. Seal strip
should be applied centered over the holes of the one
flange, making sure to fully cover holes and center over
the other large flange. See Fig. 37.
14. Slide two 20 x 25-in. filters into cross members of hood
assembly. Attach filter cover over filters with screws and
speed clips provided. See Fig. 38.
TOP
FLANGE
BLACK
SEAL
STRIP
HOOD SIDE
Fig. 24 — Adding Seal Strip to Top of Hood Sides
GRAY FOAM STRIP
CROSS MEMBER
Fig. 25 — Adding Foam Strip to Cross Member
HOOD
SIDE
CROSS
MEMBER
HOOD
SIDE
HOOD
TOP
Fig. 26 — Economizer Hood Assembly
Fig. 27 — Top Hood with Speed Clips
