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Bryant Induced-Combustion 4-Way Multipoise 310AAV User Manual

Page 9

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Outdoor Combustion Air Method

1. Provide the space with sufficient air for proper combustion,

ventilation, and dilution of flue gases using permanent hori-
zontal or vertical duct(s) or opening(s) directly communicat-
ing with the outdoors or spaces that freely communicate with
the outdoors.

2. Fig. 7 illustrates how to provide TWO OUTDOOR OPEN-

INGS, one inlet and one outlet combustion and ventilation air
opening, to the outdoors.

a. One opening MUST commence within 12

″ (300 mm) of

the ceiling and the second opening MUST commence
within 12

″ (300 mm) of the floor.

b. Size openings and ducts per Fig. 7 and Table 2.

c. TWO HORIZONTAL DUCTS require 1 square inch of

free area per 2,000 Btuh (1,100 mm

2

/kW) of combined

input for all gas appliances in the space per Fig. 7 and Table
2.

d. TWO OPENINGS OR VERTICAL DUCTS require 1

square inch of free area per 4,000 Btuh (550 mm

2

/kW) for

combined input of all gas appliances in the space per Fig.
7 and Table 2.

3. ONE OUTDOOR OPENING requires:

a. 1 square inch of free area per 3,000 Btuh (734 mm

2

/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 connectors 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.

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.

CARBON MONOXIDE POISONING HAZARD
Failure to supply outdoor air via grilles or ducts could result
in death 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.

Table 2–Minimum Free Area Required for Each Combustion Air Opening or Duct to Outdoors

FURNACE

INPUT

(BTUH)

TWO HORIZONTAL DUCTS

(1 SQ. IN./2,000 BTUH) (1,100 SQ. MM/KW)

SINGLE DUCT OR OPENING

(1 SQ. IN./3,000 BTUH) (734 SQ. MM/KW)

TWO OPENINGS OR VERTICAL DUCTS

(1 SQ. IN./4,000 BTUH) (550 SQ. MM/KW)

Free Area of

Opening and Duct

(Sq. In.)

Round Duct

(in. Dia)

Free Area of

Opening and Duct

(sq In.)

Round Duct

(in. Dia)

Free Area of

Opening and Duct

(Sq In.)

Round Duct

(In. Dia)

44,000

22

6

14.7

5

11

4

66,000

33

7

22

6

16.5

5

88,000

44

8

29.3

7

22

6

110,000

55

9

36.7

7

27.5

6

132,000

66

10

44

8

33

7

154,000

77

10

51.3

9

38.5

8

EXAMPLES: Determining Free Area

FURNACE

WATER HEATER

TOTAL INPUT

110,000

+

30,000

=

(140,000 divided by 4,000)

=

35.0 Sq. In. for each two Vertical Ducts or Openings

66,000

+

40,000

=

(106,000 divided by 3,000)

=

35.3 Sq. In. for a Single Duct or Opening

88,000

+

30,000

=

(118,000 divided by 2,000)

=

59.0 Sq. In. for each of two Horizontal Ducts

Table 3–Minimum Space Volumes for 100% Combustion, Ventilation, and

Dilution from Indoors

ACH

OTHER THAN FAN-ASSISTED TOTAL

(1,000’S BTUH GAS INPUT RATE)

FAN-ASSISTED TOTAL

(1,000’S BTUH GAS INPUT RATE)

30

40

50

44

66

88

110

132

154

Space Volume (ft

3

)

0.60

1,050

1,400

1,750

1,100

1,650

2,200

2,750

3,300

3,850

0.50

1,260

1,680

2,100

1,320

1,980

2,640

3,300

3,960

4,620

0.40

1,575

2,100

2,625

1,650

2,475

3,300

4,125

4,950

5,775

0.30

2,100

2,800

3,500

2,200

3,300

4,400

5,500

6,600

7,700

0.20

3,150

4,200

5,250

3,300

4,950

6,600

8,250

9,900

11,550

0.10

6,300

8,400

10,500

6,600

9,900

13,200

16,500

19,800

23,100

0.00

NP

NP

NP

NP

NP

NP

NP

NP

NP

NP = Not Permitted

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