Ductwork Acoustical Treatment; Supply Air Connections; Return Air Connections - Bryant 352mav Installation, Start-Up, And Operating Instructions Manual

FURNACE
CD5 OR CK5
COIL ASSEMBLY
OR KCAKC
COIL BOX
COMBUSTIBLE
FLOORING
SHEET METAL
PLENUM
FLOOR
OPENING
Fig. 20—Furnace, Plenum, and Coil Assembly or Coil
Box Installed on a Combustible Floor
PERFORATED
DISCHARGE DUCT
FLANGE
Fig. 21—Duct Flanges
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 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. clearance from combustible materials to supply air
ductwork for a distance of 36 in. horizontally from the furnace. See
NFPA 90B or local code for further requirements.
A96284
NO
YES
210°
MIN
YES
A93029
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.
B. Ductwork Acoustical Treatment
Metal duct systems that do not have a 90 degree elbow and 10 ft
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.
C. Supply Air Connections
UPFLOW FURNACES
Connect supply-air duct to 3/4-in. 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 accesso-
ries 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 combus-
tible material, supply-air duct attachment must ONLY be con-
nected to an accessory subbase or factory approved air condition-
ing 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. 21.
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.
D. Return Air Connections
The furnace and its return air system shall be designed and
installed so that negative pressure created by the air circulating fan
cannot affect another appliance's combustion air supply or act to
mix products of combustion with circulating air. The air circulat-
ing fan of the furnace, if installed in an enclosure communicating
with another fuel-burning appliance not of the direct-vent type,
shall be operable only when any door or panel covering an opening
in the furnace fan compartment or in a return air plenum on ducts
is in the closed position.
WARNING: FIRE HAZARD
Failure to follow this warning could result in fire,
personal injury, or death.
Never connect return-air ducts to the back of the furnace.
Return-air duct connections on furnace side(s) permitted
in upflow applications only.
UPFLOW FURNACES
The return-air duct must be connected to bottom, sides (left or
right), or a combination of bottom and side(s) of main furnace
casing. Bypass humidifier may be attached into unused side return
air portion of the furnace casing. DO NOT connect any portion of
return-air duct to back of furnace casing.
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