Bryant 352AAV Installation, Start-Up, And Operating Instructions Manual page 19

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. (mm)
44,000 22 (14194)
66,000
33 (21290)
88,000 44 (28387)
110,000
55 (35484)
132,000 66 (42581)
154,000
77 (49677)
EXAMPLE: Determining Free Area
FURNACE WATER HEATER
110,000 + 30,000
66,000
+ 40,000
88,000 + 30,000
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)
30
ACH
1,050
0.60
(29.7)
1,260
0.50
(35.6)
1,575
0.40
(44.5)
2,100
0.30
(59.4)
3,150
0.20
(89.1) (118.9)
6,300
0.10
(178.3) (237.8)
0.00
NP
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 13.
b. Not less than the sum of the areas of all vent
connectors in the space.
The opening shall commence within 12 in. (305 mm)
of the ceiling. Appliances in the space shall have
clearances of at least 1 in. (25 mm) from the sides and
back and 6 in. (152 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.
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.
SINGLE DUCT OR OPENING
(1 SQ. IN./3,000 BTUH) (734 SQ. MM/KW)
Round Duct Free Area of Opening
Dia. and Duct
In. (mm) Sq. In (mm)
6 (152) 14.7 (9494)
7 (178) 22 (14193)
8 (203) 29.3 (18903)
9 (229) 36.7 (23677)
10 (254) 44 (28387)
10 (254) 51.3 (33096)
TOTAL INPUT
= (140,000 divided by 4,000)
= (106,000 divided by 3,000)
= (118,000 divided by 2,000)
40 50
1,400 1,750 1,100
(39.6) (49.5) (31.1)
1,680 2,100 1,320
(47.5) (59.4) (37.3)
2,100 2,625 1,650
(59.4) (74.3) (46.7)
2,800 3,500 2,200
(79.2) (99.1) (62.2)
4,200 5,250 3,300
(148.6) (93.4)
8,400 10,500 6,600
(297.3) (186.8)
NP NP
2
/kW)
2
/kW)
Round Duct
Dia.
In. (mm)
5 (127)
6 (152)
7 (178)
7 (178)
8 (203)
9 (229)
= 35.0 Sq. In. for each two Vertical Ducts or Openings
= 35.3 Sq. In. for a Single Duct or Opening
= 59.0 Sq. In. for each of two Horizontal Ducts
FAN-ASSISTED TOTAL
(1,000'S BTUH GAS INPUT RATE)
44 66 88
3 3
Space Volume Ft (M )
1,650 2,200
(46.7) (62.2)
1,980 2,640
(56.0) (74.7)
2,475 3,300
(70.0) (93.4)
3,300 4,400
(93.4) (124.5)
4,950 6,600
(140.1) (186.8)
9,900 13,200
(280.3) (373.7)
NP NP NP
Indoor Combustion AirE 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.
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
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 2 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 2 - - Minimum Space Volumes were determined by using
the following equations from the National Fuel Gas Code ANSI
Z223.1- -2006/NFPA 54- -2006,9.3.2.2:
19
TWO OPENINGS OR VERTICAL DUCTS
(1 SQ. IN./4,000 BTUH) (550 SQ. MM/KW)
Free Area of Opening Round Duct
and Duct
Sq. In (mm) In. (mm)
11 (7097) 4 (102)
16.5 (10645) 5 (127)
22 (14193) 6 (152)
27.5 (17741) 6 (152)
33 (21290) 7 (198)
38.5 (24838) 8 (203)
110 132
2,750 3,300
(77.8) (93.4)
3,300 3,960
(93.4) (112.1)
4,125 4,950
(116.8) (140.1)
5,500 6,600
(155.7) (186.8)
8,250 9,900
(233.6) (280.3)
16,500 19,800
(467.2) (560.6)
NP NP
Dia.
154
3,850
(109.0)
4,620
(130.8)
5,775
(163.5)
7,700
(218.0)
11,550
(327.0)
23,100
(654.1)
NP