Bryant 340MAV III. Supply AIR Connections, IV. Return AIR Connections, Filter Arrangement

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.

III. SUPPLY AIR CONNECTIONS

A. 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.

B.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.

C.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.

IV. 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, and that the air circulating fan of the furnace, if installed in an enclosure commu- nicating 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 in the closed position.

WARNING: Never connect return-air ducts to the back of the furnace. Return-air duct connections on furnace side(s) permitted in upflow applications only. A failure to follow this warning could result in fire, personal injury, or death.

V.FILTER ARRANGEMENT

→CAUTION: Never operate a unit without a filter or with

filter access door removed. Failure to follow this caution will result in minor unit operation or performance satis- faction.

Factory-supplied washable framed filters are shipped in blower compartment. Determine location for filter and relocate filter retaining wire if necessary. See Table 2 to determine correct filter size for desired filter location. Table 2 indicates filter size, location, and quantity shipped with this furnace. See Fig. 2 for location and size of bottom and side return-air openings.

CAUTION: Use care when cutting support rods in filters to protect against flying pieces and sharp rod ends. Wear safety glasses, gloves, and appropriate protective cloth- ing. Failure to follow this caution could result in minor personal injury.

→CAUTION: For airflow requirements above 1800 CFM, see Air Delivery table in Product Data literature for specific use of single side inlets. The use of both side

inlets, a combination of 1 side and the bottom, or the bottom only will ensure adequate return air openings for airflow requirements above 1800 CFM. Failure to follow this caution will result in minor unit operation or perfor- mance satisfaction.

NOTE: Side return-air openings can ONLY be used in UPFLOW configurations. Install filter(s) as shown in Fig. 23. Bottom return-air opening may be used with all 4 orientations. Filter may need to be cut to fit some furnace widths. Install filter as shown in Fig. 24.

A.Upflow Furnaces

Fig. 23—Filter Installed for Side Inlet

A00217

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 return air portion of the furnace casing. DO NOT connect any portion of return-air duct to back of furnace casing.

B.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 furnace.

NOTE: Remove and discard bottom closure panel when bottom inlet is used.

TABLE 2—FILTER INFORMATION

FURNACE	FILTER SIZE (IN.)			FILTER TYPE
CASING
	Side Return	Bottom Return		FRAMED
WIDTH (IN.)
17-1/2	(1) 16 X 25 X 1†	(1) 16 X 25	X 1	Cleanable
21	(1) 16 X 25 X 1*	(1) 20 X 25	X 1†	Cleanable
24-1/2	(1 or 2) 16 X 25 X 1*	(1) 24 X 25	X 1†	Cleanable

*Filters can be field modified by cutting frame as marked and folding to desired size. Alternate sizes can be ordered from your distributor or dealer.

† Factory-provided with furnace.

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