28
Step 8 — Position Power Exhaust/Barometric
Relief Damper Hood —
All units are shipped with the
hoods folded inside the unit in a shipping position. For
50A2,A3,A6,A7 units the hood must be tilted out once the
unit is installed. On 50A4,A5,A8,A9 units (designed for
horizontal supply and return), the assemblies will have to be
relocated to return ductwork. See Fig. 39 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 (50A020-050 units) or 6 (50A060 units) power
exhaust blowers and motors or barometric relief dampers.
1. Remove 9 screws holding each damper assembly in
place. See Fig. 40. Each damper assembly is secured with
3 screws on each side and 3 screws along the bottom.
Save screws.
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 9 — Route 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. 41. A section of field-supplied
1
/
4
-in. plastic tubing must
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
2
/
3
of the way out on the main
supply duct. Remove plug button in panel to route tubing.
BUILDING PRESSURE TRANSDUCER — The building
pressure transducer (modulating power exhaust pressure trans-
ducer) is located behind the filter access door on the lower in-
ner panel. See Fig. 41. A section of field-supplied
1
/
4
-in. plastic
tubing must be run from the high-pressure tap on the differen-
tial 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 lob-
by so that the building exterior doors will open and close prop-
erly. 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 build-
ing, route the high tap to atmosphere and the low tap to build-
ing air.
FLANGE
POINTING
DOWN
MOUNTING
ANGLE
Fig. 36 — Bottom Filters Installed with Flange
Pointing Down
Fig. 37 — Attaching Seal Strip to Filter Cover
48-1110f
BLACK
S
EAL
S
TRIP
(CENTERED)
FILTER COVER
FILTER
COVER
FILTERS
Fig. 38 — Slide Two Filters
CAUTION
Be careful when tilting blower assembly. Hoods and blow-
ers are heavy and can cause injury if dropped.
