Bryant 350AAV Installation, Start-Up, And Operating Instructions Manual page 17

Outdoor Combustion Air Method
1. Provide the space with sufficient air for proper combustion,
ventilation, and dilution of flue gases using permanent
horizontal or vertical duct(s) or opening(s) directly commu-
nicating with the outdoors or spaces that freely communi-
cate with the outdoors.
2. Fig. 18 illustrates how to provide TWO OUTDOOR OPEN-
INGS, one inlet and one outlet combustion and ventilation
air openings 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. 18 and Table 1.
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 Fig. 18 and
Table 1.
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
Fig. 18 and Table 1.
3. ONE OUTDOOR OPENING requires:
a. 1 square inch of free area per 3,000 Btuh (734 mm
for combined input of all gas appliances in the space per
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" (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
→
TABLE 1—MINIMUM FREE AREA REQUIRED FOR EACH COMBUSTION AIR OPENING OR DUCT TO OUTDOORS
TWO HORIZONTAL DUCTS
(1 SQ. IN./2,000 BTUH) (1,100 SQ. MM/KW)
FURNACE
INPUT
Free Area of
(BTUH)
Opening and Duct
(Sq. In.)
44,000 22
66,000 33
88,000 44
110,000 55
132,000 66
154,000 77
→
EXAMPLES: DETERMINING FREE AREA
FURNACE WATER HEATER
110,000 +
66,000 +
88,000 +
→ TABLE 2—MINIMUM SPACE VOLUMES FOR 100% COMBUSTION, VENTILATION AND DILUTION AIR FROM OUTDOORS
OTHER THAN FAN-ASSISTED TOTAL
(1,000'S BTUH GAS INPUT RATE)
ACH
30
0.60 1,050
0.50 1,260
0.40 1,575
0.30 2,100
0.20 3,150
0.10 6,300
0.00 NP
2
/kW) of combined
2
2
(1 SQ. IN./3,000 BTUH) (734 SQ. MM/KW)
Round Duct
(in. Dia)
6
7
8
9
10
10
TOTAL INPUT
30,000 = (140,000 divided by 4,000)
40,000 = (106,000 divided by 3,000)
30,000 = (118,000 divided by 2,000)
40 50
1,400 1,750
1,680 2,100
2,100 2,625
2,800 3,500
4,200 5,250
8,400 10,500
NP NP
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 combustion air is permitted for combustion, ventilation,
and dilution, if the Standard or Known-Air-Infiltration Rate
Method is used.
WARNING: 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.
/kW)
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 appliances
/kW)
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
SINGLE DUCT OR OPENING
Free Area of
Round Duct
Opening and Duct
(in. Dia)
(sq In.)
14.7
22
29.3
36.7
44
51.3
= 35.0 Sq. In. for each two Vertical Ducts or Openings
=
=
(1,000'S BTUH GAS INPUT RATE)
44 66
3
Space Volume (ft )
1,100 1,650
1,320 1,980
1,650 2,475
2,200 3,300
3,300 4,950
6,600 9,900
NP NP
—17—
TWO OPENINGS OR VERTICAL DUCTS
(1 SQ. IN./4,000 BTUH) (550 SQ. MM/KW)
Free Area of
Opening and Duct
(Sq In.)
5 11
6 16.5
7 22
7 27.5
8 33
9 38.5
35.3 Sq. In. for a Single Duct or Opening
59.0 Sq. In. for each of two Horizontal Ducts
FAN-ASSISTED TOTAL
88 110 132
2,200 2,750 3,300
2,640 3,300 3,960
3,300 4,125 4,950
4,400 5,500 6,600
6,600 8,250 9,900
13,200 16,500 19,800
NP NP NP
Round Duct
(In. Dia)
4
5
6
6
7
8
154
3,850
4,620
5,775
7,700
11,550
23,100
NP