11
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
engineering, 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 block-
ing 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 fire-
places may create conditions requiring special attention to avoid unsat-
isfactory operation of installed gas utilization equipment. Air from
Inside Building. See 5.3.3-a.
VI. INST
VI. INST
VI. INST
VI. INST
VI. INSTALL
ALL
ALL
ALL
ALLA
A
A
A
ATI
TI
TI
TI
TIO
O
O
O
ON POSITI
N POSITI
N POSITI
N POSITI
N POSITIO
O
O
O
ONS
NS
NS
NS
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. HO
VII. HO
VII. HO
VII. HO
VII. HORIZO
RIZO
RIZO
RIZO
RIZONT
NT
NT
NT
NTAL APPLI
AL APPLI
AL APPLI
AL APPLI
AL APPLIC
C
C
C
CA
A
A
A
ATI
TI
TI
TI
TIO
O
O
O
ONS & CO
NS & CO
NS & CO
NS & CO
NS & CONSID
NSID
NSID
NSID
NSIDERA
ERA
ERA
ERA
ERATI
TI
TI
TI
TIO
O
O
O
ONS
NS
NS
NS
NS
G
ENERAL
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:
LOCATION
Horizontal Furnace
D
RAIN
T
RAP
AND
L
INES
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.
L
EVELING
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.
A
LTERNATE
V
ENT
/F
LUE
AND
C
OMBUSTION
A
IR
C
ONNECTIONS
In horizontal installations, provisions for alternate vent/flue piping
is available for upflow furnaces with left air discharge. Counterflow
furnaces include provisions for both alternate vent/flue and com-
bustion air piping with right air discharge. These configurations
allow the flue and combustion air piping to be run vertically through
the furnace. Refer to the “Recommended Installation Positions”
figure for further detail. The standard piping connections 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 air connections.