DISCHARGE DUCT
FLANGE
NO
Horizontal Furnaces
(onnect supply-air &ct to supply air opening on ftm_ace The
supply-air duct attachment must ONLY be connected to ftmaace
supply/outlet or air conditioning coil casing (when used) DO NOT
cut main f_rnace casing to attach supply side air duct, humidifier,
or other accessories. All accessories MUST be connected external
to fhrnace main casing.
I I
210 ° .....................
MIN
Fig. 23--Duct Flanges
YES
YES
A93029
Flexible connections should be used between ductwork and
_;,/rnace to prevent transmission of vibration Ductwork passing
through unconditioned space should be insulated to enhance
system perforn_ance. When air conditioning is use& a vapor
barrier is recommended.
Maintain a l-in. clearance fi'om comhustible materials to supply air
ductwork fbr a distance of 36 in. horizontally fiom the t_urnace. See
NFPA 90B or local code fbr _hrther requirements.
For a fhmace not equipped with a cooling coil, the outlet duct shall
be provided with a removable access panel. This opening shall be
accessible when the ft,.mace is installed and shall be of such a size
that the heat exchanger can be viewed %r possible openings using
light assistance or a probe can be inserted for sampling the air
stream. The cover attachment shall prevent leaks.
DU(TWORK ACOUSTICAL TREATMENT
Metal duct systems that do not have a 90 degree elbow and 10 fi
of main &ct to the first branch rake-off may require internal
acoustical lining As an ahernative, 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%r (lass 1 Rigid air ducts.
SUPPLY AIR (ONNECTIONS
L pflow Furnaces
Connect supply-air duct to 3/4-in flange on _hrnace supply-air
outlet. The supply-air duct attachment must ONLY be connected
to fbrnace supply-/outlet-air duct flanges or air conditioning coil
casing (when used) DO NOT cut main fhmace casing to attach
supply side air duct, humidifier, or other accessories. All accesso-
ries MUST be connected external to ft_rnace main casing
Downflow Furnaces
(onnect supply-air duct to supply-air opening on t_urnace. The
supply-air duct attachment must ONLY be connected to t'umace
supply/outlet or air conditioning coil casing (when used), when
installed on non-comhustible material. When installed on comhus-
tible material, supply-air duct attachment nmst ONLY be con-
nected to an accesso_- subbase or _i_ctory approved air condition-
ing coil casing. DO NOT cut main fhmace casing to attach supply
side air duct, humidifier, or other accessories. All accessories
MUST be connected external to fi/rnace main casing.
--9
2O
RETETRN AIR (ONNECTIONS
The t:t_rnace and its remm air system shall be designed and
installed so that negative pressure created by the air circulating fan
cannot a£f_ct another appliance's air supply or act to mix products
of combustion with circulating air, and that the air circulating fan
of the fhrnace, if installed in an enclosure communicating with
another fhel-burning appliance not of the direct-vent type, shall be
operable only when any door or panel covering an opening in the
ft_rnace fan compartment or in a return air plenum on ducts is in
the closed position.
FIRE HAZARD
A failure to %11ow this warning could result in fire, personal
Jr{jury, or death
Never connect return-air ducts to the back of the t'umace
Return-air duct connections on ftm_ace side(s) pem_itted 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 as shown in Fig 2 Bypass humidifier may be attached into
unused side remm air portion of the furnace casing. DO NOT
connect any portion of return-air duct to back of furnace casing.
Downflow and Horizontal Furnaces
The return-air duct must be connected to return-air opening
provided as shown in Fig. 2 DO NOT cut into casing sides or back
to attach any portion of return-air duct Bypass humidifier connec-
tions should be made at ductwork or coil casing sides exterior to
ft_rnace
Step 5--FHter Arrangement
FIRE, CARBON MONOXIDE AND POISONING
HAZARD
Failure to %11ow this warning could result in fire, personal
injury, or death
Never operate unit without a filter or with blower access
panel removed.
Factory-supplied washable framed filters are shipped in blower
comparm_ent Determine location %r filter and relocate filter
retaining wire if necessaD- See Table 4 to determine correct filter
size %r desired filter location. Table 4 indicates filter size,
location, and quantity- shipped with this _hmace. See Fig. 2 for
location and size of bottom and side return-air openings.
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