Outside Air; Free Area - Arcoaire N9MP1 Installation Instruction

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
Outlet Air (1)
Ventilated Crawl Space
alternate Inlet Air (1)
c. Horizontal duct openings require 1 square inch of free
area per 2,000 BTUH (1,100 mm
for 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 (550 mm
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 (700 mm
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" of the top of the
enclosure. Appliances shall have clearances of at least 1" from the
sides and back and 6" from the front. The opening shall directly
Table 1

Free Area

BTUH
Input
Two Horizontal Ducts
Rating
(sq. in./2,000 BTUH)
40,000
50,000
60,000
75,000
80,000
100,000
125,000
EXAMPLE: Determining Free Area
Furnace Water Heater
100,000 +
Furnace Water Heater
100,000 +
10
This installation NOT approved in Canada
alternate Inlet Air (1)
Gas Vent
Soffit Vent
Inlet
Air (1)
2
/kW) of combined input
or openings
2
/kW) for combined
2
Minimum Free Area Required for Each Opening or Duct to Outdoors
(sq. in./3,000 BTUH)
20 sq. in.
25 sq. in.
30 sq. in.
37.5 sq. in.
40 sq. in.
50 sq. in.
62.50 sq. in.
30,000 = (130,000 ÷ 4,000)
30,000 = (130,000 ÷ 2,000)
Specifications are subject to change without notice
Gable Vent
Ventilated Attic
Top Above Insulation
Soffit Vent
OutletAir (1)
Inlet
Air (2)
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.
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.
/kW) for
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
13.3 sq. in.
16.7 sq. in.
20 sq. in.
25 sq. in.
26.7 sq. in.
33.3 sq. in.
41.7 sq. in.
Total Input
=
Total Input
=
Gas Vent
Outlet
Air (1)
Inlet
Air (1)
Minimum One Inlet and One Outlet Air Supply is Required
May be in any Combination Shown
Inlet Air Opening Must be Within12" of floor
Outlet Air Opening Must be Within12" of ceiling
(1) 1 Square Inch per 4000 BTUH
(2) 1 Square Inch per 2000 BTUH
openings that comply
(sq. in./4,000 BTUH)
10.0 sq. in.
12.5 sq. in.
15.0 sq. in.
18.75 sq. in.
20.0 sq. in.
25 sq. in.
31.25 sq. in.
32.5 Sq. In. Vertical
65 Sq. In. Horizontal
Outlet
Air (2)
Inlet
Air (2)
with the
Indoor
Round Duct
(sq. in. /4,000 BTUH)
4"
4"
4"
5"
5"
6"
7"
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