International comfort products N9MP1 Installation Instructions Manual page 11

5. When sizing a grille, louver, or screen use the free area of
opening. If free area is NOT stamped or marked on grill or
louver, assume a 20% free area for wood and 60% for metal.
Screens shall have a mesh size not smaller than
Requirements
1. Provide the space with sufficient air for proper combustion and
ventilation of flue gases using horizontal or vertical ducts or
openings.
Outside Air (This is ONLY a guide. Subject to codes of country having jurisdiction.)
Figure 6
Gable Vent
Gas Vent
Ventilated Attic
Top Above Insulation
        Â
        Â
Outlet Air (1)
Á Á Á Á Á Á Á Á Á
Ventilated Crawl Space
Á Á Á Á Á Á Á Á Á
alternate Inlet Air (1)
c. Horizontal duct openings require 1 square inch of free
area per 2,000 BTUH (11 cm
all gas appliances in the space (see Table 1).
d. Vertical duct openings
communicating with the outdoors require 1 square inch
of free area per 4,000 BTUH (5.5 cm
input of all gas appliances in the space (see Table 1).
3. When one permanent outdoor opening is used, the opening
requires:
1 sq. in of free area per 3,000 BTUH (7 cm
a.
combined input of all gas appliances in the space (see
Table 1) and
b.
not less than the sum of the areas of all vent connectors
in the space.
The opening shall commence within 12" (304.8mm) of the top of
the enclosure. Appliances shall have clearances of at least 1"
(25.4mm) from the sides and back and 6" (152.4mm) from the
front. The opening shall directly communicate with the outdoors or
Table 1
Free Area
BTUH (kW)
Two Horizontal Ducts
Input
Rating
sq. in./2,000(1 cm
40,000 (11.72) 20 sq. in. (129 cm
50,000 (14.65) 25 sq. in. (161 cm
60,000 (17.58) 30 sq. in. (194 cm
75,000 (21.98) 37.5 sq. in. (242 cm
80,000 (23.45) 40 sq. in. (258 cm
100,000 (29.31) 50 sq. in. (322 cm
125,000 (36.63) 62.50 sq. in. (403 cm
EXAMPLE: Determining Free Area
Furnace Water Heater
100,000 +
29.31
Furnace Water Heater
100,000
+
29.31
440 01 1024 04
1
/ " (6.4mm).
4
This installation NOT approved in Canada
alternate Inlet Air (1)
Gas Vent
É É
Soffit Vent
        Â
        Â
OutletAir (1)
Inlet
É É
Air (1)
2
/kW) of combined input for
or openings
2
/kW) for combined
2
/kW) for
Minimum Free Area Required for Each Opening or Duct to Outdoors
BTUH (kW)
2
/.09) sq. in./3,000 (1 cm
2
) 13.34 sq. in. (86 cm
2
) 16.7 sq. in. (108 cm
2
) 20 sq. in. (129 cm
2
) 25 sq. in. (161 cm
2
) 26.7 sq. in. (172 cm
2
) 33.3 sq. in. (215 cm
2
) 41.7 sq. in. (269 cm
30,000 = (130,000 ÷ 4,000)
8.8
30,000 (130,000 ÷ 2,000)
=
8.8
Specifications are subject to change without notice
2. Figure 6 illustrates how to provide combustion and ventilation
air when two permanent openings, one inlet and one outlet,
are used.
a. One opening MUST commence within 12" (304.8mm) of
the floor and the second opening MUST commence
within 12" (304.8mm) of the ceiling.
b. Size openings and ducts per Table 1.
Gable Vent
Ventilated Attic
Top Above Insulation
É É
Soffit Vent
Inlet
Air (2)
shall communicate through a vertical or horizontal duct to the
outdoors or spaces (crawl or attic) that freely communicate with
the outdoors.
directly
4. Combination of Indoor and Outdoor Air shall have:
a. Indoor
Combustion Air Method below and
b. Outdoor openings located as required in the Outdoor
Combustion Air Method above and
c. Outdoor openings sized as follows.
1) Calculate the Ratio of all Indoor Space volume
divided by required volume for Indoor Combustion Air
Method.
2) Outdoor opening size reduction Factor is 1 minus the
Ratio in 1) above.
3) Minimum size of Outdoor openings shall be the size
required in Outdoor Combustion Air Method above
multiplied by reduction Factor.
Single Opening Two Vertical Ducts or Openings
BTUH (kW)
2
/.135)
2
)
2
)
2
)
2
)
2
)
2
)
2
)
Total Input
= 32.5 Sq. In. Vertical
(38.11 ÷ .18)
= 210 c
Total Input
= 65 Sq. In. Horizontal
(38.11 ÷ .09)
= 423
Gas Vent
        Â
É Â Â Â Â Â Â Â Â Â
É
Outlet
Air (1)
É
Inlet
Air (1)
É
Minimum One Inlet and One Outlet Air Supply is Required
May be in any Combination Shown
Inlet Air Opening must be within 12" (304.8mm) of floor
Outlet Air Opening must be within 12" (304.8mm) of ceiling
(1) 1 Square Inch per 4000 BTUH
(2) 1 Square Inch per 2000 BTUH
openings that comply
BTUH (kW)
2
sq. in./4,000(1 cm /.18) sq. in./4,000(6.5cm
2
10 sq. in. (65 cm )
2
12.5 sq. in. (81 cm )
2
15 sq. in. (97 cm )
2
18.75 sq. in. (121 cm )
2
20 sq. in. (129 cm )
2
25 sq. in. (161 cm )
2
31.25 sq. in. (202 cm )
2 Vertical
m
2
Horizontal
cm
É
Outlet
Air (2)
Inlet
Air (2)
with the Indoor
Round Duct
BTUH (kW)
2
/.18)
4" (101.6mm)
4" (101.6mm)
4" (101.6mm)
5" (127mm)
5" (127mm)
6" (152.4mm)
7" (177.8mm)
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