Installation & Operation Manual
41
Nominal
Iron Pipe
Size
(inches)
Natural Gas Pipe Capacity Chart
Length of Pipe in Straight Feet
Maximum
Capacity of Pipe
in Thousands of
Btu/hr per hour
for gas pressures
of 14 Inches
Water Column
(0.5 PSIG) or less
and a pressure
drop of 0.5 Inch
Water Column
(Based on NAT
GAS, 1025 Btu/hr
per Cubic Foot of
Gas and 0.60
Specific Gravity)
10
20
30
40
50
60
70
80
90
100
125
150
175
200
1/2
175
120
97
82
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
3/4
369
256
205
174
155
141
128
121
113
106
95
86
79
74
1
697
477
384
328
292
267
246
236
210
200
179
164
149
138
1-1/4
1400
974
789
677
595
543
502
472
441
410
369
333
308
287
1-1/2
2150
1500
1210
1020
923
830
769
707
666
636
564
513
472
441
2
4100
2820
2260
1950
1720
1560 1440 1330 1250 1180 1100
974
871
820
2-1/2
6460
4460
3610
3100
2720
2460 2310 2100 2000 1900 1700 1540 1400 1300
3
11200 7900
6400
5400
4870
4410 4000 3800 3540 3330 3000 2720 2500 2340
4
23500 16100 13100 11100 10000 9000 8300 7690 7380 6870 6150 5640 5130 4720
7
Gas connections
(continued)
Table 7A
Natural Gas Pipe Size Chart
The gas piping must be sized for the proper flow and length of
pipe, to avoid excessive pressure drop. Both the gas meter and
the gas regulator must be properly sized for the total gas load.
If you experience a pressure drop greater than 1 inch w.c.
(249 Pa), the meter, regulator, or gas line is undersized or in
need of service. Perform the steps below when checking inlet
gas supply:
1.
Turn the main power switch to the “OFF” position.
2.
Shut off gas supply at the manual gas valve in the gas
piping to the appliance.
3.
On Models 399 - 500 loosen the set screw one (1) full turn
from inside the pressure tap on top of the gas valve. On
Models 600 - 800 remove the 1/8" (3 mm) pipe plug on the
inlet flange to the valve and install a suitable 1/8" (3 mm)
fitting (field supplied) for the manometer tubing. Place
the tubing of the manometer over the tap once the set
screw is loosened or the 1/8" (3 mm) fitting is installed
(depending on model) as shown in FIG.’s 7-5 thru 7-7 on
page 42.
4.
Slowly turn on the gas supply at the field installed
manual gas valve.
5.
Turn the power switch to the “ON” position.
6.
Adjust the temperature set point on the control panel of
the SMART SYSTEM control module to call for heat.
7.
Observe the gas supply pressure as the burner fires at
100% of rated input. Percent of burner input will be
displayed on the control panel.
8.
Ensure inlet pressure is within specified range.
Minimum and maximum gas supply pressures are
specified in this section of the manual.
9.
If gas supply pressure is within normal range and no
adjustments are needed, proceed on to Step 11.
10. If the gas pressure is out of range, contact the gas utility,
gas supplier, qualified installer or service agency to
determine the necessary steps to provide proper gas
pressure to the control.
11. Turn the power switch to the “OFF” position.
12. Shut off the gas supply at the manual gas valve in the gas
piping to the appliance.
13. Remove the manometer from the pressure tap on top of
the gas valve. On Models 399 - 500 re-tighten the set
screw inside the pressure tap. On Models 600 - 800
remove the 1/8" (3 mm) field supplied fitting and
reinstall the pipe plug removed in Step 3.
Check inlet gas supply
NOTICE
CSA or UL listed flexible gas connections
are acceptable, but you must exercise
caution to ensure that the line has adequate
capacity to allow your boiler to fire at full
rate. Consult with local codes for proper
installation or service procedures.
DO NOT adjust or attempt to measure gas
valve outlet pressure. Attempting to alter
or measure the gas valve outlet pressure
could result in damage to the valve, causing
potential severe personal injury, death, or
substantial property damage.
WARNING
