Bryant Bruant 4 Way Gas 355AAV - Manual (Page 21)

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Manufacturer’s Coil Assembly or when Manufacturer’s Coil Box is
used.
1. Determine application being installed from Table 3.
2. Construct hole in floor per dimensions specified in Table 3
and Fig. 22.
3. Construct plenum to dimensions specified in Table 3 and
Fig. 22.
4. If downflow subbase is used, install as shown in Fig. 23.
5. If coil assembly is used, install as shown in Fig. 24.
NOTE: Remove furnace perforated discharge duct flanges when
they interfere with mating flanges on coil on downflow subbase.
To remove furnace perforated discharge duct flange, use hand
seamers, wide duct pliers or duct flange tool to bend flange back
and forth until it breaks off. Be careful of sharp edges. (See Fig.
25.)
UNIT MAY NOT OPERATE
Failure to follow this caution may result in intermittent unit
operation or performance satisfaction.
Do not bend duct flanges inward as shown in Fig. 25. This
will affect airflow across heat exchangers and may cause limit
cycling or premature heat exchanger failure. Remove duct
flange completely or bend it inward a minimum of 210_ as
shown in Fig. 25.
CAUTION
!
Step 3 — Installation in Horizontal Applications
These furnaces can be installed in either horizontal left or right
discharge position. In a crawlspace, furnace can either be hung
from floor joist or installed on suitable blocks or pad. Furnace can
be suspended from each corner by hanger bolts and angle iron
supports. (See Fig. 26.) Cut hanger bolts (4 each 3/8--in. (10 mm)
all--thread rod) to desired length. Use 1 X 3/8--in. (10 mm) flat
washers, 3/8--in. (10 mm) lock washers, and 3/8--in. (10 mm) nuts
on hanger rods as shown in Fig. 26. Dimples are provided for hole
locations. (See Fig. 2.)
UNIT MAY NOT OPERATE
Failure to follow this caution may result in intermittent unit
operation or performance satisfaction.
The entire length of furnace MUST be supported when
furnace is used in a horizontal position to ensure proper
draining. When suspended, bottom brace supports sides and
center blower shelf. When unit is supported from the ground,
blocks or pad should support sides and center blower shelf
area.
CAUTION
!
Step 4 — Air Ducts
GENERAL REQUIREMENTS
The duct system should be designed and sized according to
accepted national standards such as those published by: Air
Conditioning Contractors Association (ACCA), Sheet Metal and
Air Conditioning Contractors National Association (SMACNA) or
American Society of Heating, Refrigerating and Air Conditioning
Engineers (ASHRAE) or consult The Air Systems Design
Guidelines reference tables available from your local distributor.
The duct system should be sized to handle the required system
design CFM at the design static pressure.
When a furnace is installed so that the supply ducts carry air
circulated by the furnace to areas outside the space containing the
furnace, the return air must also be handled by a duct(s) sealed to
the furnace casing and terminating outside the space containing the
furnace.
Secure ductwork with proper fasteners for type of ductwork used.
Seal supply-- and return--duct connections to furnace with code
approved tape or duct sealer.
Flexible connections should be used between ductwork and
furnace to prevent transmission of vibration. Ductwork passing
through unconditioned space should be insulated to enhance
system performance. When air conditioning is used, a vapor barrier
is recommended.
Maintain a 1--in. (25 mm) clearance from combustible materials to
supply air ductwork for a distance of 36 in. (914 mm) horizontally
from the furnace. See NFPA 90B or local code for further
requirements.
For a furnace not equipped with a cooling coil, the outlet duct shall
be provided with a removable access panel. This opening shall be
accessible when the furnace is installed and shall be of such a size
that the heat exchanger can be viewed for possible openings using
light assistance or a probe can be inserted for sampling the air
stream. The cover attachment shall prevent leaks.
DUCTWORK ACOUSTICAL TREATMENT
Metal duct systems that do not have a 90 degree elbow and 10 ft.
(3.0 M) of main duct to the first branch take--off may require
internal acoustical lining. As an alternative, fibrous ductwork may
be used if constructed and installed in accordance with the latest
edition of SMACNA construction standard on fibrous glass ducts.
Both acoustical lining and fibrous ductwork shall comply with
NFPA 90B as tested by UL Standard 181 for Class 1 Rigid air
ducts.
SUPPLY AIR CONNECTIONS
Upflow Furnaces
Connect supply--air duct to 3/4--in. (19.1 mm) flange on furnace
supply--air outlet. The supply--air duct attachment must ONLY be
connected to furnace supply--/outlet--air duct flanges or air
conditioning coil casing (when used). DO NOT cut main furnace
casing to attach supply side air duct, humidifier, or other
accessories. All accessories MUST be connected external to
furnace main casing.
Downflow Furnaces
Connect supply--air duct to supply--air opening on furnace. The
supply--air duct attachment must ONLY be connected to furnace
supply/outlet or air conditioning coil casing (when used), when
installed on non--combustible material. When installed on
combustible material, supply--air duct attachment must ONLY be
connected to an accessory subbase or factory approved air
conditioning coil casing. DO NOT cut main furnace casing to
attach supply side air duct, humidifier, or other accessories. All
accessories MUST be connected external to furnace main casing.
Supply air opening duct flanges must be modified per Fig. 25.
Horizontal Furnaces
Connect supply--air duct to supply air opening on furnace. The
supply--air duct attachment must ONLY be connected to furnace
supply/outlet or air conditioning coil casing (when used). DO NOT
cut main furnace casing to attach supply side air duct, humidifier,
or other accessories. All accessories MUST be connected external
to furnace main casing.
355A