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Gas Piping
NATURAL GAS
Pipe Sizing - Natural Gas
1. Refer to Table 3 for pipe length and diame-
ter requirements. Based on rated PER-
FORMANCE PLUS input (divide by 1,000
to obtain cubic feet per hour).
- Table 3 is based on Natural Gas with a
specific gravity of 0.60 and a pressure
drop through the gas piping of
0.30”w.c..
- For additional gas piping sizing infor-
mation, refer to ANSI Z223.1. For
Canadian installations refer to B149.1
or B149.2.
Natural Gas Supply Pressure Requirements
1. Pressure required at the gas valve inlet
supply pressure port:
- Maximum 13”w.c. at flow or no flow
conditions to the burner.
- Minimum 5”w.c. during flow condi-
tions to the burner. Must be verified
during start up and with all gas appli-
ances operating.
2. Install 100% lockup gas pressure regulator
in the gas supply line if inlet pressure can
exceed 13”w.c at any time. Adjust the lock-
up pressure regulator for 13”w.c maximum.
DO NOT adjust or attempt to measure
gas valve outlet pressure. The gas valve
is factory-set for the correct outlet pres-
sure. This setting is suitable for natural
gas and propane and requires no field
adjustment. Attempts by the installer to
adjust or measure the gas valve outlet
pressure could result in damage to the
valve, causing potential severe personal
i n j u r y, death or substantial pro p e rt y
damage.
WARNING
Length of Pipe
in Feet
SCH 40 1/2" 3/4" 1" 1-1/4" 1-1/2"
10 132 278 520 1050 1600
20 92 190 350 730 1100
30 73 152 285 590 860
40 63 130 245 500 760
50 56 115 215 440 670
75 45 93 175 360 545
100 38 79 150 305 460
150 31 64 120 250 380
Capacity of Pipe in Cubic Feet of Gas Per Hour
(based on 0.60 specific gravity, 0.30" w.c. pressure drop)
Table 3: Gas piping sizing - Natural Gas