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52
Gas Supply
Table 3 - Pipe-Sizing - Natural Gas
Schedule 40 Metallic Pipe (Black Iron)
Inlet System Pressure: Less than 2 PSI (55 inches W.C.)
Allowable Pressure Drop: 0.5 inches W.C.
Specic Gravity : 0.60
(Capacity in cubic feet per hour)
Length Pipe Size (Inches)
½ ¾ 1 1¼ 1½
10 172 360 678 1390 2090
20 118 247 466 957 1430
30 95 199 374 768 1150
40 81 170 320 657 985
50 72 151 284 583 873
60 65 137 257 528 791
70 60 126 237 486 728
80 56 117 220 452 677
90 52 110 207 424 635
100 50 104 195 400 600
Information in this chart obtained from NFPA 54, ANSI Z223.1 - 2012 Table 6.2(b)
Table 4 - Pipe-Sizing - Natural Gas
Schedule 40 Metallic Pipe (Black Iron)
Inlet System Pressure: 8.0 inches W.C. or greater, but Less than 2 PSI (55
inches W.C.)
Allowable Pressure Drop: 3.0 inches W.C.
Specic Gravity : 0.60
(Capacity in cubic feet per hour)
Length Pipe Size (Inches)
½ ¾ 1 1¼ 1½
10 454 949 1,787 3,669 5,497
20 312 652 1,228 2,522 3,778
30 250 524 986 2,025 3,778
40 214 448 844 1,733 2,597
50 190 387 748 1,536 2,302
60 172 360 678 1,392 2,085
70 158 331 624 1,280 1,919
80 147 308 580 1,191 1,785
90 138 289 544 1,118 1,675
100 131 273 514 1,056 1,582
Information in this chart obtained from NFPA 54, ANSI Z223.1 - 2012 Table 6.2(c)
Table 5 - Pipe-Sizing - Undiluted Propane
Schedule 40 Metallic Pipe (Black Iron)
Inlet System Pressure: 11 inches W.C.
Allowable Pressure Drop: 0.5 inches W.C.
Specic Gravity : 1.5
(Capacity in cubic feet per hour)
Length Pipe Size (Inches)
½ ¾ 1 1¼ 1½
10 291 608 1150 2350 3520
20 200 418 787 1620 2420
30 160 336 632 1300 1940
40 137 287 541 1110 1660
50 122 255 480 985 1480
60 110 231 434 892 1340
80 101 212 400 821 1230
100 94 197 372 763 1140
125 89 185 349 716 1070
150 84 175 330 677 1010
Information in this chart obtained from NFPA 54, ANSI Z223.1 - 2012 Table 6.3(d)
Table 2 - Pipe-Sizing - Natural Gas
Schedule 40 Metallic Pipe (Black Iron)
Inlet System Pressure: Less than 2 PSI (55 inches W.C.)
Allowable Pressure Drop: 0.3 inches W.C.
Specic Gravity : 0.60
(Capacity in cubic feet per hour)
Length Pipe Size (Inches)
½ ¾ 1 1¼ 1½
10 131 273 514 1,060 1,580
20 90 188 355 726 1,090
30 72 151 284 583 873
40 62 129 243 499 747
50 55 114 215 442 662
60 50 104 195 400 600
70 46 95 179 368 552
80 42 89 167 343 514
90 40 83 157 322 482
100 38 79 148 304 455
Information in this chart obtained from NFPA 54, ANSI Z223.1 - 2012 Table 6.2(a)
Final Considerations
If this water heater is replacing an existing water heater,
it is important to verify the capacity of the gas system.
Check the capacity of the meter/regulator, and verify
the pipe lengths and sizes.
An improperly sized gas system will cause operational
issues with this water heater. Other appliances on the
gas system may be affected as well.
Flexible Gas Connectors may be used however the
BTU capacity of the connector must be checked. Each
connector has a capacity label on it, verify that the
connector has a BTU capacity greater than that of the
water heater. An undersized flexible gas connector will
cause operational issues with this water heater.
Half-inch gas lines are permissible provided the gas
system meets certain requirements. First, the gas
pressure on the system must be 8.0 inch W.C. or
greater. Second the capacity of the pipe as outlined in
Table 4 is followed. If the existing pipes are too small
it could cause a pressure drop greater than 3.0 inch
W.C. and will cause operational issues with this water
heater as well as other gas appliances on the system.
This is an example, in US, refer to current National Fuel
Gas Code, NFPA 54 for correct pipe sizing chart, and
in Canada, refer to current Natural Gas and Propane
Installation Code CAN/CSA B149.1.
Gas Supply (cont.)
INSTALLATION INSTRUCTIONS
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