Step 9 - Make Outdoor-Air Inlet; Adjustments; Economizer And Fixed Outdoor Air Damper; Step 10 - Position Power Exhaust/Barometric - Carrier WEATHERMAKER 48A2 Installation Instructions Manual

Step 9 — Make Outdoor-Air Inlet Adjustments
ECONOMIZER AND
DAMPER — Hoods are used on all units with economizer or
adjustable self-closing fixed 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 48A4,A5 units
are side supply and side return. The return duct limits access to
economizer filters from below.
The 48A2,A3,A4,A5020-050 units have two hoods on ev-
ery unit. The 48A2,A3,A4,A5060 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 economizer
hood.
1. Apply black seal strip (provided) to outside top-edge of
hood sides. Wrap seal strip over edge to cover top flange
(6 hood sides). Make sure seal strip covers screw holes.
Allow strip to overhang
mounting flange. See Fig. 23.
2. Assemble hood sides, top, and cross member with
gasketed screws provided. See Fig. 24.
3. Attach 15 green speed clips (provided) to hood top.
4. Apply black seal strip (provided) to mounting flanges of
hood sides being sure to cover mounting holes. See
Fig. 25.
5. 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. 26.
6. Add gray foam strip (provided) to cross members on bot-
tom tray. See Fig. 27.
7. Attach gray foam strip (provided) to block-off baffle on
outer face of flange. See Fig. 28.
8. Remove the screws on each end and along top of damper
assembly of unit. Remove top 4 screws on each side of
filter panel under damper assembly. Set hood assembly in
place and attach to unit using these screws.
9. Remove screws along bottom of damper assembly.
Locate and mount block-off baffle using these screws.
10. Assemble 2 filter tracks side-by-side with the assembled
ends together.
11. Attach one mounting angle to the assembled end of the
filter track. See Fig. 29.
12. Attach 9 green speed clips (provided) to hood side panels.
Engagement section of clip faces up and towards the out-
side of the hood side panels.
13. Attach remaining mounting angle to other end of the filter
track with no. 10 screws provided.
14. Place filter track assembly in bottom of hood by attaching
to hood with speed clips and gasketed screws provided.
NOTE: Be sure the filters are installed with the airflow in the
correct direction.
15. 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 centered over
the other large flange. See Fig. 30.
FIXED OUTDOOR AIR
1
/ -in. past the end opposite the
8
16. Slide two 20 x 25-in. filters into cross members of hood
assembly. Attach filter cover over filters with screws and
speed clips provided.
Step 10 — Position Power Exhaust/Barometric
Relief Damper Hood —
hoods folded inside the unit in a shipping position. For 48A2,
and A3 units the hood must be tilted out once the unit is in-
stalled. On 48A4, A5 units, (designed for horizontal supply and
return) the assemblies will have to be relocated to return duct-
work. See Fig. 31 for dimensions and details.
All electrical connections have been made and adjusted at
the factory. The power exhaust blowers and barometric relief
dampers are shipped assembled and tilted back into the unit for
shipping. Brackets and extra screws are shipped in shrink wrap
around the dampers. If ordered, each unit will have 4
(48A2,A3,A4,A5020-050 units) or 6 (48A2,A3,A4,A5060
units) power exhaust blowers and motors or barometric relief
dampers.
1. Remove 9 screws holding each damper assembly in
place. See Fig. 32. Each damper assembly is secured with
3 screws on each side and 3 screws along the bottom.
Save screws.
Be careful when tilting blower assembly. Hoods and blow-
ers are heavy and can cause injury if dropped.
2. Pivot each damper assembly outward until edges of
damper assembly rest against inside wall of unit.
3. Secure each damper assembly to unit with 6 screws
across top (3 screws provided) and bottom (3 screws
from Step 1) of damper.
4. With screws saved from Step 1, install brackets on each
side of damper assembly.
5. Remove tape from damper blades.
Step 11 — Route VAV Static Pressure Sensors
VAV DUCT PRESSURE TRANSDUCER — The VAV duct
pressure transducer (VAV inverter pressure transducer) is locat-
ed behind the filter access door on the lower inner panel. See
Fig. 33. A section of field-supplied
be run from the high pressure tap on the differential pressure
switch and connected to a field-supplied tap in the supply-air
duct. The tap is usually located
supply duct. Remove plug button in panel to route tubing.
VAV BUILDING PRESSURE TRANSDUCER — The VAV
building pressure transducer (modulating power exhaust pres-
sure transducer) is located behind the filter access door on the
lower inner panel. See Fig. 33. A section of field-supplied
1 / -in. plastic tubing must be run from the high pressure tap on
4
the differential pressure switch to the conditioned space. The
pressure tube must be terminated in the conditioned space
where a constant pressure is required. This location is usually
in an entrance lobby so that the building exterior doors will
open and close properly. Remove plug button in panel to route
tubing.
The low pressure tap is factory-routed to the atmosphere.
For a positive-pressure building, route the high tap to building
air and low tap to atmosphere. For a negative-pressure
building, route the high tap to atmosphere and the low tap to
building air.
Step 12 — Install All Accessories —
factory-installed options have been adjusted, install all field-
installed accessories. Refer to the accessory installation instruc-
tions included with each accessory.
30
All units are shipped with the
CAUTION
1
/ -in. plastic tubing must
4
2
/ of the way out on the main
3
After all the