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INSTALLATION - GAS CONNECTIONS
GAS CONNECTIONS
W ARNING
1. All field gas piping must be pressure/leak tested prior to
operation. Never use an open flame. Use a soap solution
or equivalent for testing.
2. Gas pressure to appliance controls must never exceed
14" W.C. (1/2 psi).
3. To reduce the opportunity for condensation, the minimum
sea level input to the appliance, as indicated on the serial
plate, must not be less than 5% below the rated input, or
5% below the minimum rated input of dual rated units.
CAUTION
1. Purging of air from gas lines should be performed as
described in the National Fuel Gas Code, ANSI Z223.1
(NFPA 54) - latest edition or in Canada CSA-B149 codes.
2. When leak testing the gas supply piping system, the
appliance and its combination gas control must be isolated
during any pressure testing in excess of 14" W.C. (1/2 psi).
3. The unit should be isolated from the gas supply piping
system by closing its field installed manual shut-off
valve. This manual shut-off valve should be located within
6' of the heater.
4. Turn off all gas before installing appliance.
IMPOR T ANT
To prevent premature heat exchanger failure, the input to
the appliance, as indicated on the serial plate, must not
exceed the rated input by more than 5%.
1. Installation of piping must conform with local building codes,
or in the absence of local codes, with the National Fuel Gas
Code, ANSI Z223.1 (NFPA 54) - latest Edition. In Canada,
installation must be in accordance with CSA-B149.1.
2. Piping to units should conform with local and national
requirements for type and volume of gas handled, and
pressure drop allowed in the line. Refer to Table 11.1 to
determine the cubic feet per hour (CFH) for the type of gas
and size of unit to be installed. Using this CFH value and the
length of pipe necessary, determine the pipe diameter from
Table 11.2. Where several units are served by the same
main, the total capacity, CFH and length of main must be
considered. Avoid pipe sizes smaller than 1/2". Table 11.2
allows for a 0.3" W.C. pressure drop in the supply pressure
from the building main to the unit. The inlet pressure to the
unit must be 6-7" W.C. for natural gas and 11-14" W.C. for
propane gas. When sizing the inlet gas pipe diameter, make
sure that the unit supply pressure can be met after the
0.3" W.C. has been subtracted. If the 0.3" W.C. pressure
drop is too high, refer to the Gas Engineer's Handbook for
other gas pipe capacities.
3. Install a ground joint union with brass seat and a manual
shut-off valve adjacent to the unit for emergency shut-off and
easy servicing of controls, including a 1/8" NPT plugged
tapping accessible for test gauge connection (see Figure 11.1).
4. Use 2 wrenches when connecting field piping to units.
5. Provide a sediment trap before each unit in the line where
low spots cannot be avoided (see Figure 11.1).
6. When pressure/leak testing, pressures above 14" W.C.
(1/2 psi), close the field installed shut-off valve, disconnect
the appliance and its combination gas control from the gas
supply line, and plug the supply line before testing. When
testing pressures 14" W.C. (1/2 psi) or below, close the
manual shut-off valve on the appliance before testing.
Figure 11.1 - Recommended Sediment Trap/Manual Shut-off
Valve Installation - Side or Bottom Gas Connection
Table 11.1 - Sea Level Manifold Pressure
& Gas Consumption
Model
Manifold Pressure
Size
("W.C.):
CFH
150
Gal/Hr.Propane
Orifice Drill Size
CFH
175
Gal/Hr.Propane
Orifice Drill Size
CFH
Gal/Hr.Propane
200
Orifice Drill Size
CFH
250
Gal/Hr.Propane
Orifice Drill Size
CFH
300
Gal/Hr.Propane
Orifice Drill Size
CFH
350
Gal/Hr.Propane
Orifice Drill Size
CFH
400
Gal/Hr.Propane
Orifice Drill Size
Table 11.2 - Gas Pipe Capacities - Natural Gas
Pipe Length
1/2"
(ft)
10
132
92
20
30
73
40
63
56
50
60
50
46
70
80
43
100
38
34
125
150
31
Capacities in cubic feet per hour through schedule 40 pipe with maximum
0.3" W.C. pressure drop with up to 14" W.C. gas pressure. Specific gravity is 0.60
for natural gas and 1.50 for propane gas.
‚ For pipe capacity with propane gas, divide natural gas capacity by 1.6. Example:
What is the propane gas pipe capacity for 60 feet of 1-1/4" pipe? The natural gas
capacity is 400 CFH. Divide by 1.6 to get 250 CFH for propane gas.
6-561.12
Manual shut-off valve is in the
"OFF" position when handle is
perpendicular to pipe.
Natural
Propane
# of
3.5
10
Orifices
142.9
60.0
n/a
1.6
6
42
53
166.7
70.0
n/a
1.9
7
42
53
190.5
80.0
n/a
2.2
7
38
52
238.1
100.0
n/a
2.7
9
39
1.55 mm
285.7
120.0
n/a
3.3
9
36
51
333.3
140.0
n/a
3.8
12
38
52
381.0
160.0
n/a
4.4
12
36
51
Natural Gas
3/4"
1"
1-1/4" 1-1/2"
278
520
1050
1600
190
350
730
1100
152
285
590
890
130
245
500
760
115
215
440
670
105
195
400
610
96
180
370
560
90
170
350
530
79
150
305
460
72
130
275
410
64
120
250
380
➀ ‚
2"
3050
2100
1650
1450
1270
1150
1050
930
870
780
710
11
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