Installation instructions
35
Greentherm T9900 SE/i – 6 720 813 635 (2019/03)
4.8.2 Gas Line Sizing Tables for LP GAS
For your convenience, see below an excerpt from gas line sizing tables for a single LP appliance. Their intended use is for pipe sizing
between the 2nd stage (low pressure) regulator and the appliance. For details, see the current NFPA 54 or NFPA 58.
Required input for 160000 / 199000 BTU/hr for the Greentherm T9900 SE/i. The gas supply system must be sized for the
combined total maximum BTU/hr load requirements of all gas appliances running simultaneously.
Table 14 Maximum capacity of the gas supply pipe in thousands of BTU per hour of Undiluted LP Gas at 11" W.C (0.4 psig or 27.4
mbar) based on a pressure drop of 0.5" W.C (1.25 mbar).
Table 15 Maximum capacity in thousands of BTU of the gas supply pipe per hour of Undiluted LP Gas at 11" W.C (0.4 psig or 27.4
mbar) based on a pressure drop of 0.5" W.C (1.25 mbar).
* EHD = Equivalent Hydraulic Diameter. The greater the value of EHD, the greater the gas capacity of the tubing.
Table 16 Maximum capacity in thousands of BTU of the gas supply pipe per hour of Undiluted LP Gas at 11" W.C (0.4 psig or 27.4
mbar) based on a pressure drop of 0.5" W.C (1.25 mbar).
* Source National Fuel Gas Code NFPA 54, ANSI Z223.1 - No Additional Allowance is necessary for an ordinary number of fittings.
Pipe Sizing Between Single- or Second-Stage (Low-Pressure) Regulator and Appliance
Nominal
Iron
Pipe inches
Internal
Diameter
inches
Length of Black Iron Pipe (Schedule 40 Metallic Pipe), Feet
10
20
30
40
50
60
80
100
1/2
0.622
291
200
160
137
122
110
101
94
3/4
0.824
608
418
336
287
255
231
212
197
1
1.049
1150
787
632
541
480
434
400
372
CSST Sizing Between Single- or Second-Stage (Low-Pressure) Regulator and Appliance Shutoff Valve
EHD*
Length of Corrugated Stainless Steel Tubing (CSST), Feet
10
20
30
40
50
60
70
80
90
100
23
254
183
151
131
118
107
99
94
90
85
25
303
216
177
153
137
126
117
109
102
98
30 521
365
297
256
227
207
191
178
169
159
31
605
425
344
297
265
241
222
208
197
186
Tube Sizing Between Single- or Second-Stage (Low-Pressure) Regulator and Appliance
Nominal
tube
inches
Internal
Diameter
inches
Length of Semirigid Copper Tubing, Feet
10
20
30
40
50
1/2
0.527
188
129
104
89
79
5/8
0.652
329
226
182
155
138