F96CTN and G96CTN (Series A): Installation, Start-up, Operating, Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
9
EXAMPLES: Determining Free Area
Table 4 – Minimum Space Volumes for 100% Combustion, Ventilation and Dilution Air from Outdoors
NP = Not Permitted
L12F012
Fig. 6 – Air for Combustion, Ventilation, and Dilution for Outdoors
L12F013
Fig. 7 – Air for Combustion, Ventilation, and Dilution from Indoors
The opening shall commence within 12 in. (300 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. (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.
FURNACE
WATER HEATER
TOTAL INPUT
100,000
+
30,000
=
(130,000 divided by 4,000)
=
32.5 Sq. In. for each two Vertical Ducts or Openings
60,000
+
40,000
=
(100,000 divided by 3,000)
=
33.3 Sq. In. for each Single Duct or Opening
80,000
+
30,000
=
(110,000 divided by 2,000)
=
55.0 Sq. In. for each two Horizontal Ducts
OTHER THAN FAN-ASSISTED TOTAL
(1,000’S BTUH GAS INPUT RATE)
FAN-ASSISTED TOTAL
(1,000’S BTUH GAS INPUT RATE)
ACH
30
40
50
40
60
80
100
120
140
Space Volume Ft3 (M3)
0.60
1,050 (29.7)
1,400 (39.6)
1,750
(49.5)
1,400 (39.6) 1,500 (42.5) 2,000 (56.6) 2,500 (70.8) 3,000 (84.9) 3,500 (99.1)
0.50
1,260 (35.6)
1,680 (47.5)
2,100
(59.4)
1,680 (47.5) 1,800 (51.0) 2,400 (67.9) 3,000 (84.9) 3,600 (101.9) 4,200 (118.9)
0.40
1,575 (44.5)
2,100 (59.4)
2,625
(74.3)
2,100 (59.4) 2,250 (63.7) 3,000 (84.9) 3,750 (106.1) 4,500 (127.3) 5,250 (148.6)
0.30
2,100 (59.4)
2,800 (79.2)
3,500
(99.1)
2,800 (79.2) 3,000 (84.9) 4,000 (113.2) 5,000 (141.5) 6,000 (169.8) 7,000 (198.1)
0.20
3,150 (89.1) 4,200 (118.9)
5,250
(148.6)
4,200 (118.9) 4,500 (127.3) 6,000 (169.8) 7,500 (212.2) 9,000 (254.6)
10,500
(297.1)
0.10
6,300 (178.0) 8,400 (237.8)
10,500
(297.3)
8,400 (237.8) 9,000 (254.6)
12,000
(339.5)
15,000
(424.4)
18,000
(509.2)
21,000
(594.1)
0.00
NP
NP
NP
NP
NP
NP
NP
NP
NP
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