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5. When directly communicating with the outdoors, the single open-
ing shall have a minimum free area of 1 square inch per 3,000
BTU per hour of total input rating of all equipment in the enclo-
sure.
5.3.4 Specially Engineered Installations:
The requirements of 5.3.3 shall not necessarily govern when special engi-
neering, approved by the authority having jurisdiction, provides an
adequate supply of air for combustion, ventilation, and dilution of flue
gases.
5.3.5 Louvers and Grilles:
In calculating free area in 5.3.3, consideration shall be given to the blocking
effect of louvers, grilles or screens protecting openings. Screens used
shall not be smaller than 1/4 inch mesh. If the area through a design of
louver or grille is known, it should be used in calculating the size of
opening required to provide the free area specified. If the design and free
area is not known, it may be assumed that wood louvers will have 20-25
percent free area and metal louvers and grilles will have 60-75 percent
free area. Louvers and grilles shall be fixed in the open position or
interlocked with the equipment so that they are opened automatically
during equipment operation.
5.3.6 Special Conditions Created by Mechanical Exhausting or Fire-
places:
Operation of exhaust fans, ventilation systems, clothes dryers, or fireplaces
may create conditions requiring special attention to avoid unsatisfac-
tory operation of installed gas utilization equipment. Air from Inside
Building. See 5.3.3-a.
VI. INSTVI. INST
VI. INSTVI. INST
VI. INST
ALLALL
ALLALL
ALL
AA
AA
A
TITI
TITI
TI
OO
OO
O
N POSITIN POSITI
N POSITIN POSITI
N POSITI
OO
OO
O
NSNS
NSNS
NS
This furnace may be installed in an upright position or horizontal
on either the left or right side panel. Do not install this furnace on
its back. For upright upflow furnaces, return air ductwork may be
attached to the side panel(s) and/or basepan. For horizontal up-
flow furnaces, return air ductwork must be attached to the basepan.
For both upright or horizontal counterflow furnaces, return duct-
work must be attached to the basepan (top end of the blower com-
partment). NOTE: Ductwork must never be attached to the back of
the furnace. Contact your distributor for proper airflow require-
ments and number of required ductwork connections. Refer to
“Recommended Installation Positions” figure for appropriate in-
stallation positions, ductwork connections, and resulting airflow
arrangements.
VII. HOVII. HO
VII. HOVII. HO
VII. HO
RIZORIZO
RIZORIZO
RIZO
NTNT
NTNT
NT
AL APPLIAL APPLI
AL APPLIAL APPLI
AL APPLI
CC
CC
C
AA
AA
A
TITI
TITI
TI
OO
OO
O
NS & CONS & CO
NS & CONS & CO
NS & CO
NSIDNSID
NSIDNSID
NSID
ERAERA
ERAERA
ERA
TITI
TITI
TI
OO
OO
O
NSNS
NSNS
NS
GENERAL
Horizontal applications, in particular, may dictate many of the
installation’s specifics such as airflow direction, ductwork connec-
tions, flue and combustion air pipe connections, etc. The basic
application of this furnace as a horizontal furnace differs only slightly
from an upright installation. When installing a furnace horizontally,
additional consideration must be given to the following:
ALTERNATE VENT/FLUE
AND COMBUSTION AIR
INTAKE LOCATIONS
FURNACE MUST BE LEVEL
FROM END TO END
FURNACE MUST BE LEVEL
OR SLIGHTLY TILTED FORWARD
WITH THE DOORS 0" - 3/4"
BELOW THE BACK PANEL
DRAIN LINE WITH 1/4" PER FOOT
DOWNWARD SLOPE
24"
MINIMUM
CLEARANCE
REQUIRED
FURNACE MUST BE SUPPORTED
AT BOTH ENDS AND MIDDLE
DRAIN PAN
GAS LINE WITH
DRIP LEG (3" MINIMUM)
4 3/4" MINIMUM
DRAIN TRAP
CLEARANCE
SERVICE
Horizontal Furnace
DRAIN TRAP AND LINES
In horizontal applications the condensate drain trap is secured to
the furnace side panel, suspending it below the furnace. A mini-
mum clearance of 4 3/4 inches below the furnace must be pro-
vided for the drain trap. Additionally, the appropriate downward
piping slope must be maintained from the drain trap to the drain
location. Refer to Section X, Condensate Drain Trap and Lines for
further details. If the drain trap and drain line will be exposed to
temperatures near or below freezing, adequate measures must
be taken to prevent condensate from freezing.
LEVELING
Leveling ensures proper condensate drainage from the heat ex-
changer and induced draft blower. For proper flue pipe drainage,
the furnace must be level lengthwise from end to end. The furnace
should also be level from back to front or have a slight tilt with the
access doors downhill (approximately 3/4 inches) from the back
panel. The slight tilt allows the heat exchanger condensate, gen-
erated in the recuperator coil, to flow forward to the recuperator coil
front cover.
ALTERNATE V ENT/FLUE AND C OMBUSTION A IR C ONNECTIONS
In horizontal installations provisions for alternate flue and com-
bustion air piping are available for upflow furnaces with left dis-
charge and counterflow furnaces with right air discharge. This con-
figuration allows the flue and combustion air piping to be run verti-
cally through the furnace. Refer to the “Recommended Installation
Positions” figure for further detail. The standard piping connec-
tions may also be used in these positions. Refer to Section IX,
Vent/Flue Pipe and Combustion Air Pipe for details concerning the
conversion to the alternate vent/flue and combustion air connec-
tions.