Water Heater Installation Manual
31 Page
-Natural gas supply piping-
Maximum delivery Capacity in Cubic Feet of Gas per Hour (based on IPS Pipe carrying Natural Gas with 0.60
Specific Gravity with a Pressure Drop of 0.5" W.C.).
Based on Energy Content of 1,000 BTU/Cubic ft: The water heater requires 160 Cubic ft/hr for the 240HX3 model, 180
Cubic ft/hr for the 340HX3 model, and 199 Cubic ft/hr for the 540HX3 model.
The following tables are from NFPA 54.
-Propane (LP) supply piping-
Maximum Capacity of Propane (LP) Based on 11" W.C. supply pressure at a 0.5" W.C. pressure drop
Pipe Size
Length
Diameter
10'
(3 .0 m)
20'
(6.1 m)
30'
(9.1 m)
40'
(12.2 m)
50'
(15.2 m)
60'
(18.3 m)
70'
(21.3 m)
80'
(24.4 m)
90'
(27.4 m)
100'
(30.5 m)
125'
(38.1 m)
150'
(45.7 m)
200'
(61.0 m)
1/2"
172 118 95 81 72 65 60 56 52 50 44 40 34
3/4"
360 247 199 170 151 137 126 117 110 104 92 83 71
1"
678 466 374 320 284 257 237 220 207 195 173 157 134
1,390 957 768 657 583 528 486 452 424 400 355 322 275
1-1/2"
2,090 1,430 1,150 985 873 791 728 677 635 600 532 482 412
2"
4,020 2,760 2,220 1,900 1,680 1,520 1,400 1,300 1,220 1,160 1,020 928 794
Unit: Cubic feet per hour
Water
heater
199,000 BTU/h
Dryer
35,000 BTU/h
Gas meter
Furnace
120,000 BTU/h
Range
65,000 BTU/h
A
B
C
10' (3 m)Length
1/2" Pipe size
15' (4.6 m)Length
1/2" Pipe size
15' (4.6 m)Length
1" Pipe size
10'(3 m)Length
3/4" Pipe size
10' (3 m )Length
1" Pipe size
5' (1.5 m) Length
1-1/4" Pipe size
10' (3 m)Length
3/4" Pipe size
5' (1.5 m)Length
1-1/4" Pipe size
Gas sizing example
(Natural Gas)
Unit: kBTU per hour
Pipe Size
Length
Diameter
10'
(3 .0 m)
20'
(6.1 m)
30'
(9.1 m)
40'
(12.2 m)
50'
(15.2 m)
60'
(18.3 m)
70'
(21.3 m)
80'
(24.4 m)
90'
(27.4 m)
100'
(30.5 m)
125'
(38.1 m)
150'
(45.7 m)
200'
(61.0 m)
1/2"
268 184 148 126 112 101 93 87 82 77 68 62 53
3/4"
567 393 315 267 237 217 196 185 173 162 146 132 112
1"
1,071 732 590 504 448 409 378 346 322 307 275 252 213
1-1/4"
2,205 1,496 1,212 1,039 913 834 771 724 677 630 567 511 440
1-1/2"
3,307 2,299 1,858 1,559 1,417 1,275 1,181 1,086 1,023 976 866 787 675
2"
6,221 4,331 3,465 2,992 2,646 2,394 2,205 2,047 1,921 1,811 1,606 1,496 1,260
Based on Energy Content of 1,000 BTU/Cubic ft:
Divide each appliance's BTU/h requirement by 1,000 BTU/ft
3
to get the appliance's ft
3
/h requirement.
Take into account the distance the appliance is from the gas meter, then look in the above gas chart to properly size the line.
For sections of the gas line supplying gas to more than one appliance (Ex: Point A to Point B), add up the cubic ft per hour
requirements of the appliances that are being supplied by that section, and size to the farthest appliance.
For Example: The section from A to B supplies gas to the furnace, range and dryer. Adding up the BTU/h requirements and
dividing by 1,000 yields a cubic ft per hour requirement of 220 cubic ft of gas per hour. The farthest appliance is the range,
which is 50 ft away from the meter. Looking at the above chart, and under the column of 50 ft, Section A to B needs to be
1" in order to supply 220 cubic ft.
Installaon
Installaon Manual