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FURNACE
CASING
WIDTH
IN. (mm)
Upflow Applications on Combustible or Noncombustible
Downflow Applications on Noncombustible Flooring
14–3/16
(360)
Downflow applications on Combustible Flooring
Downflow Applications on Combustible Flooring with coil
assembly or coil box (subbase not required)
Upflow Applications on Combustible or Noncombustible
Downflow Applications on Noncombustible Flooring
17–1/2
(445)
Downflow Applications on Combustible Flooring
Downflow Applications on Combustible Flooring with coil
assembly or coil box (subbase not required)
Upflow Applications on Combustible or Noncombustible
Downflow Applications on Noncombustible Flooring
21
(533)
Downflow Applications on Combustible Flooring
Downflow Applications on Combustible Flooring with coil
assembly or coil box (subbase not required)
Upflow Applications on Combustible or Noncombustible
Downflow Applications on Noncombustible Flooring
24- -1/2
(622)
Downflow Applications on Combustible Flooring
Downflow Applications on Combustible Flooring with coil
assembly or coil box (subbase not required)
Filter Arrangement
WARNING
!
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal
injury, or death.
Never operate a furnace without a filter or with filter access
door removed.
There are no provisions for an internal filter rack in these
furnaces. A field- -supplied accessory external filter rack is
required.
Refer to the instructions supplied with the external filter rack for
assembly and installation options.
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 external static pressure.
The furnace airflow rates are provided in Table 5- -Air
Delivery- -CFM (With Filter). 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 shall also
Table 4 – Opening Dimensions - - In. (mm)
APPLICATION
Flooring (subbase not required)
(subbase not required)
(subbase required)
Flooring (subbase not required)
(subbase not required)
(subbase required)
Flooring (subbase not required)
(subbase not required)
(subbase required)
Flooring (subbase not required)
(subbase not required)
(subbase required)
PLENUM OPENING
A
12- -11/16
(322)
12- -9/16
(319)
11- -13/16
(284)
12- -5/16
(319)
16
(406)
15- -7/8
(403)
15- -1/8
(384)
15- -1/2
(394)
19- -1/2
(495)
19- -3/8
(492)
18- -5/8
(473)
19
(483)
23
(584)
22- -7/8
(581)
22- -1/8
(562)
22- -1/2
(572)
be handled by 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.
NOTE: 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.
Ductwork Acoustical Treatment
NOTE: Metal duct systems that do not have a 90 degree elbow
and 10 ft. (3 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
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.
13
FLOOR OPENING
B
C
21- -5/8
13- -5/16
22- -1/4
(549)
(338)
(565)
19
13- -3/16
19- -5/8
(483)
(335)
(498)
19
13- -7/16
20- -5/8
(483)
(341)
(600)
19
13- -5/16
(483)
(338)
(508)
21- -5/8
16- -5/8
22- -1/4
(549)
(422)
(565)
19
16- -1/2
19- -5/8
(483)
(419)
(498)
19
16- -3/4
20- -5/8
(483)
(425)
(600)
19
16- -1/2
(483)
(419)
(508)
21- -5/8
20- -1/8
22- -1/4
(549)
(511)
(565)
19
20
19- -5/8
(483)
(508)
(498)
19
20- -1/4
20- -5/8
(483)
(514)
(600)
19
20
(483)
(508)
(508)
21- -1/8
23- -5/8
22- -1/4
(537)
(600)
(565)
19
23- -1/2
19- -5/8
(483)
(597)
(498)
19
23- -3/4
20- -5/8
(483)
(603)
(600)
19
23- -1/2
(483)
(597)
(508)
D
20
20
20
20
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