International comfort products N8MXL Installation Instructions Manual page 9

c. TWO HORIZONTAL DUCTS require 1 square inch of
free area per 2,000 Btuh (1,100 mm
input for all gas appliances in the space per Figure 7
and Table 2.
d. TWO OPENINGS OR VERTICAL DUCTS require 1
square inch of free area per 4,000 Btuh (550 mm
for combined input of all gas appliances in the space
per Figure 7 and Table 2.
3. ONE OUTDOOR OPENING requires:
a. 1 square inch of free area per 3,000 Btuh (734
2
mm /kW) for combined input of all gas appliances in
the space per Table 2 and
b. Not less than the sum of the areas of all vent connect-
ors in the space.
The opening shall commence within 12" (300 mm) of the
ceiling. Appliances in the space shall have clearances of at
least 1" (25 mm) from the sides and back and 6" (150 mm)
from the front. The opening shall directly communicate with
the outdoors or shall communicate through a vertical or
horizontal duct to the outdoors or spaces (crawl or attic) that
freely communicate with the outdoors.
Figure 7 − Air for Combustion, Ventilation, and Dilution
from Outdoors
DUCTS
TO
O UTDOORS
12 " MAX
(305mm)
1 SQ IN.
PER 2000 B
BTUH*
DUCT S
TO
OUTDOORS
1 SQ IN.
PER 2000
A
BTUH*
12 " MAX
(305mm)
CIRCULA TING AIR DUCT S
*Minimum dimensions of 3 in. (76 mm).
NOTE: Use any of the following combinations of openings:
A&B, C&D, D&E, F&G
Indoor Combustion Air − NFPA & AGA
Standard and Known−Air−Infiltration Rate Methods
Indoor air is permitted for combustion, ventilation, and
dilution, if the Standard or Known−Air−Infiltration Method is
used.
441 01 1421 01
2
/kW) of combined
1 SQ IN.
PER 4000
BTUH*
12 "
D
(305mm)
MAX
VENT
THR OUGH
F
R OOF
1 SQ IN .
PER
4000
BTUH*
1 SQ IN .
PER
4000
BTUH*
E
G
12 "
(305mm)
MAX
C
12 " MAX
(305mm)
DUCT
1 SQ IN.
TO
PER 4000
OUTDOORS
BTUH*
Specifications are subject to change without notice.
!
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in death
2
/kW)
and/or personal injury.
Many homes require air to be supplied from outdoors
for furnace combustion, ventilation, and dilution of flue
gases. The furnace combustion air supply must be
provided in accordance with this instruction manual.
The Standard Method:
1. The space has no less volume than 50 cubic feet per
1,000 Btuh of the maximum input ratings for all gas ap-
pliances installed in the space and
2. The air infiltration rate is not known to be less than 0.40
air changes per hour (ACH).
The Known Air Infiltration Rate Method shall be used, if the
infiltration rate is known to be:
1. Less than 0.40 ACH and
2. Equal to or greater than 0.10 ACH
Infiltration rates greater than 0.60 ACH shall not be used. The
minimum required volume of the space varies with the
number of ACH and shall be determined per Table 3 or
Equations 1 and 2. Determine the minimum required volume
for each appliance in the space and add the volumes
together to get the total minimum required volume for the
space.
Table 3 − Minimum Space Volumes were determined by
using the following equations from the National Fuel Gas
Code ANSI Z223.1−2012/NFPA 54−2012, 9.3.2.2:
1. For other than fan−assisted appliances, such as a
draft hood−equipped water heater:
Volume
2. For fan−assisted appliances such as this furnace:
Volume
If:
Iother = combined input of all other than fan−assisted
appliances
in Btuh/hr
A03174
Ifan = combined input of all fan−assisted appliances in
Btuh/hr
ACH = air changes per hour (ACH shall not exceed 0.60.)
The following requirements apply to the Standard Method
and to the Known Air Infiltration Rate Method.
1. Adjoining rooms can be considered part of a space if:
a. There are no closeable doors between rooms.
b. Combining spaces on same floor level. Each opening
shall have free area of at least 1 in.
mm
in the space, but not less than 100 in.
opening shall commence within 12" (300 mm) of the
ceiling and the second opening shall commence with-
WARNING
= 21ft
3
ACH 1000 Btu/hr
Other
= 15ft
3
ACH 1000 Btu/hr
Fan
2
/kW) of the total input rating of all gas appliances
I
other
A04002
I
fan
A004003
2
/1,000 Btuh (2,000
2 2
(0.06 m ). One
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