7
GAS PIPING
To avoid damage or possible personal injury, do not connect gas piping to this unit
until a supply line pressure/leak test has been completed. Connecting the unit before completing the
pressure/leak test may damage the unit gas valve and result in a fire hazard.
Do not rely on a shut-off valve to isolate the unit while conducting gas pressure/leak tests. These
valves may not be completely shut off, exposing the gas valve to excessive pressure and damage.
NOTICE: If more than one unit heater is to be served
by the same piping arrangement, the total cu. ft./hr.
input and length of pipe must be considered.
NOTICE: If the gas unit heater is to be fired with LP
gas, consult your local LP gas dealer for pipe size
information.
NOTICE: HEATER INSTALLATION FOR USE WITH
PROPANE (BOTTLED) GAS MUST BE MADE BY A
QUALIFIED L.P. GAS DEALER OR INSTALLER. HE/
SHE WILL INSURE THAT PROPER JOINT
COMPOUNDS ARE USED FOR MAKING PIPE
CONNECTIONS; THAT AIR IS PURGED FROM
LINES; THAT A THOROUGH TEST IS MADE FOR
LEAKS BEFORE OPERATING THE HEATER; AND
THAT IT IS PROPERLY CONNECTED TO THE
PROPANE GAS SUPPLY SYSTEM.
Before any connection is made to the existing line
supplying other gas appliances, contact the local gas
company to make sure that the existing line is of
adequate size to handle the combined load.
1. Determine the required Cu. Ft./Hr. by dividing the input by 1000. For SI/Metric measurements: Convert BTU/Hr. to kilowatts. Multiply the
units inputs (kW) by 0.0965 to determine Cu. Meters./Hr. 2. FOR NATURAL GAS: Select pipe size directly from the table. 3. FOR PROPANE
GAS: Multiply the Cu. Ft./Hr. value by 0.633; then, use the table. 4. Refer to the metric conversion factors listed in the General Safety section
for SI Unit measurement conversions.
Maximum Capacity of Pipe in Cubic Feet of Gas per Hour (Cubic Meters per Hour) for Gas Pressures of 0.5 psig (3.5 kPa) or Less,
and a Pressure Drop of 0.5 Inch Water Column (124.4 Pa)
(Based on a 0.60 Specific Gravity Gas)
Nominal
Iron
Internal
Length of Pipe, Feet (meters)
Pipe Size
Dia.
10
20
30
40
50
60
70
80
90
100
125
150
175
200
in.
in.
(3.0)
(6.1)
(9.1)
(12.2)
(15.2)
(18.3)
(21.3)
(24.4)
(27.4)
(30.5)
(38.1)
(45.7)
(53.3)
(61.0)
1/2
0.622
175
120
97
82
73
66
61
57
53
50
44
40
37
35
(4.96)
(3.40)
(2.75)
(2.32)
(2.07)
(1.87)
(1.73)
(1.61)
(1.50)
(1.42)
(1.25)
(1.13)
(1.05)
(0.99)
3/4
0.824
360
250
200
170
151
138
125
118
110
103
93
84
77
72
(10.2)
(7.08)
(5.66)
(4.81)
(4.28)
(3.91)
(3.54)
(3.34)
(3.11)
(2.92)
(2.63)
(2.38)
(2.18)
(2.04)
1
1.049
680
465
375
320
285
260
240
220
205
195
175
160
145
135
(19.3)
(13.2)
(10.6)
(9.06)
(8.07)
(7.36)
(6.80)
(6.23)
(5.80)
(5.52)
(4.96)
(4.53)
(4.11)
(3.82)
1 1/4
1.380
1400
950
770
660
580
530
490
460
430
400
360
325
300
280
(39.6)
(26.9)
(21.8)
(18.7)
(16.4)
(15.0)
(13.9)
(13.0)
(12.2)
(11.3)
(10.2)
(9.20)
(8.50)
(7.93)
1 1/2
1.610
2100
1460
1180
990
900
810
750
690
650
620
550
500
460
430
(59.5)
(41.3)
(33.4)
(28.0)
(25.5)
(22.9)
(21.2)
(19.5)
(18.4)
(17.6)
(15.6)
(14.2)
(13.0)
(12.2)
2
2.067
3950
2750
2200
1900
1680
1520
1400
1300
1220
1150
1020
950
850
800
(112)
(77.9)
(62.3)
(53.8)
(47.6)
(43.0)
(39.6)
(36.8)
(34.5)
(32.6)
(28.9)
(26.9)
(24.1)
(22.7)
2 1/2
2.469
6300
4350
3520
3000
2650
2400
2250
2050
1950
1850
1650
1500
1370
1280
(178)
(123)
(99.7)
(85.0)
(75.0)
(68.0)
(63.7)
(58.0)
(55.2)
(52.4)
(46.7)
(42.5)
(38.8)
(36.2)
3
3.068
11000
7700
6250
5300
4750
4300
3900
3700
3450
3250
2950
2650
2450
2280
(311)
(218)
(177)
(150)
(135)
(122)
(110)
(105)
(97.7)
(92.0)
(83.5)
(75.0)
(69.4)
(64.6)
4
4.026
23000
15800
12800
10900
9700
8800
8100
7500
7200
6700
6000
5500
5000
4600
(651)
(447)
(362)
(309)
(275)
(249)
(229)
(212)
(204)
(190)
(170)
(156)
(142)
(130)
Table 3 - Gas Pipe Size
PIPE SIZING
To provide adequate gas pressure to the gas unit heater,
size the gas piping as follows:
1. Find the cu. ft./hr. by using the following formula:
Input BTU/Hr.
Cu. ft./hr. =
1000
2. Refer to Table 3. Match “Length of Pipe in Feet”
with appropriate “Gas Input - Cu. Ft./Hr.” figure.
This figure can then be matched to the pipe size at
the top of the column.
Example:
It is determined that a 67 foot (20.4m) run of gas
pipe is required to connect a 200 MBTU gas unit
heater to a 1,000 BTU/cu ft. (0.29kW) natural gas
supply.
200,000 BTU/Hr
= 200 Cu. ft./hr.
1,000 BTU/cu. ft.
Using Table 3, a 1 inch pipe is needed.
NOTE: See General Safety Information section for
English/Metric unit conversion factors.
