Specifications are subject to change without notice.
13
441 01 1421 02
HORIZONTAL INSTALLATION
FIRE, EXPLOSION, AND CARBON MONOXIDE
POISONING HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Do not install the furnace on its back or hang furnace with
control compartment facing downward. Safety control
operation will be adversely affected. Never connect
return
−
air ducts to the back of the furnace.
!
WARNING
The furnace can be installed horizontally in an attic or crawl space
on either the left
−
hand (LH) or right
−
hand (RH) side. The furnace
can be hung from floor joists, rafters or trusses or installed on a
non
−
combustible platform, blocks, bricks or pad.
Suspended Furnace Support
The furnace may be supported under each end with threaded rod,
angle iron or metal plumber’s strap as shown. (See Fig. 15 and
16.) Secure angle iron to bottom of furnace as shown.
Heavy
−
gauge sheet metal straps (plumber’s straps) may be used
to suspend the furnace from each bottom corner. To prevent
screws from pulling out, use 2 #8 x 3/4
−
in. (19 mm) screws into
the side and 2 #8 x 3/4
−
in. (19 mm) screws in the bottom of the
furnace casing for each strap. (See Fig. 15 and 16.) If the screws
are attached to ONLY the furnace sides and not the bottom, the
straps must be vertical against the furnace sides and not pull away
from the furnace sides, so that the strap attachment screws are not
in tension (are loaded in shear) for reliable support.
Platform Furnace Support
Construct working platform at location where all required furnace
clearances are met. (See Fig. 2 and 17.) For furnaces with 1
−
in.
(25 mm) clearance requirement on side, set furnace on
noncombustible blocks, bricks or angle iron. For crawl space
installations, if the furnace is not suspended from the floor joists,
the ground underneath furnace must be level and the furnace set
on blocks or bricks.
Roll
−
Out Protection
Provide a minimum 17
−
3/4 in. x 22 in. (451 mm x 559 mm)
piece of sheet metal for flame roll
−
out protection in front of
burner area for furnaces closer than 12 inches (305 mm) above
the combustible deck or suspended furnaces closer than 12 inches
(305 mm) to joists. The sheet metal MUST extend underneath the
furnace casing by 1 in. (25 mm) with the door removed.
The bottom closure panel on furnaces of widths 17
−
1/2 in. (445
mm) and larger may be used for flame roll
−
out protection when
bottom of furnace is used for return air connection. See Fig. 17
for proper orientation of roll
−
out shield.
Bottom Return Air Inlet
These furnaces are shipped with bottom closure panel installed in
bottom return
−
air opening. Remove and discard this panel when
bottom return air is used. To remove bottom closure panel,
perform the following:
1. Tilt or raise furnace and remove two screws holding bot-
tom filler panel. (See Fig. 9.)
2. Rotate bottom filler panel downward to release holding
tabs.
3. Remove bottom closure panel.
4. Reinstall bottom filler panel and screws. Side Return Air
Inlet
Side Return Air Inlet
These furnaces are shipped with bottom closure panel installed in
bottom return
−
air opening. This panel MUST be in place when
side return air inlet(s) is used without a bottom return air inlet.
Not all horizontal furnaces are approved for side return air
connections. (See Fig. 21.)
FILTER ARRANGEMENT
CARBON MONOXIDE AND 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.
!
WARNING
There are no provisions for an internal filter rack in these
furnaces.
A field
−
supplied accessory external filter 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 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 and
sealed 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 airstream. The cover attachment shall prevent leaks.
