Combustion Air Supply And Ventilation - American Water Heater Flame Guard Safety System Installation Instructions And User Manual

Table 1
Natural Gas Pipe Capacity Table (Cu. Ft./Hr.)
Capacity of gas pipe of different diameters and lengths in cu. ft. per hr. with pressure drop of 0.3 in. and specific gravity
of 0.60 (natural gas).
Nominal Iron Pipe
Size, in.
10
1/2 132
3/4 278
1 520
1-1/4 1050
1-1/2 1600
After the length of pipe has been determined, select the pipe size which will provide the minimum cubic feet per hour
required for the gas input rating of the water heater. By formula:
Cu. Ft. Per Hr. Required=
The gas input of the water heater is marked on the water heater data plate. The heating value of the gas (BTU/FT )
may be determined by consulting the local natural gas utility.
Table 2
LP Gas Capacity Table
Maximum capacity of pipe in thousands of BTU per hour of undiluted liquefied petroleum gases (at 11 inches water
column pressure). Based on a pressure drop of 0.5 inch water column.
Nominal Iron Pipe
Size, in.
10
1/2
275
3/4 576
1 1071
1-1/4 2205
Example: Input BTU requirement of the water heater 100,000 BTUH.
Additional tables are available in the latest edition of the "National Fuel Gas Code", ANSI Z223.1.
Combustion Air Supply and
Ventilation
Carbon Monoxide Warning
Follow all the local and state codes or, in
the absence of local and state codes, the
"National Fuel Gas Code", ANSI Z223.1
(NFPA 54)- latest edition to properly
install vent system.
Failure to do so can result in death,
explosion, or carbon monoxide poisoning.
Important: Air for combustion and ventilation must not
come from a corrosive atmosphere. Any failure due to
corrosive elements in the atmosphere is excluded from
warranty coverage.
The following types of installation (not limited to the
following) will require outdoor air for combustion due to
chemical exposure and may reduce but not eliminate
the presence of corrosive chemicals in the air:
beauty shops
photo processing labs
buildings with indoor pools
20 30 40 50
92 73 63 56
190 152 130 115
350 285 245 215
730 590 500 440
1100 890 760 670
Gas Input of Water Heater (BTU/HR)
Heating Value of Gas (BTU/FT³)
20 30 40
189 152 129
393 315 267
732 590 504
1496 1212 1039
Total pipe length, 80 feet = 3/4" IPS required.
Length of Pipe, Feet
60 70 80 90
50 46 43 40
105 96 90 84
195 180 170 160
400 370 350 320
610 560 530 490
Length of Pipe, Feet
50 60 70 80
114 103 96 89
237 217 196 185
448 409 378 346
913 834 771 724
water heaters installed in laundry, hobby, or
craft rooms
water heaters installed near chemical storage
areas
Combustion air must be free of acid-forming chemicals
such as sulfur, fluorine, and chlorine. These elements
are found in aerosol sprays, detergents, bleaches,
cleaning solvents, air fresheners, paint, and varnish
removers, refrigerants, and many other commercial and
household products. When burned, vapors from these
products form highly corrosive acid compounds. These
products should not be stored or used near the water
heater or air inlet.
Combustion and ventilation air requirements are
determined by the location of the water heater. The
water heater may be located in either an open
(unconfined) area or in a confined area or small
enclosure such as a closet or small room. Confined
spaces are areas with less than 50 cubic feet for each
1,000 BTUH of the total input for all gas-using
appliances.
100 125 150 175
38 34 31 28
79 72 64 59
150 130 120 110
305 275 250 225
460 410 380 350
90 100 125
83 78 69
173 162 146
322 307 275
677 630 567
200
26
55
100
210
320
3
150
63
132
252
511
7