Gas Connections - Modine Manufacturing HD Manual

INSTALLATION

GAS CONNECTIONS

WARNING
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.
IMPORTANT
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 10.1 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 10.2. 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
10.1 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 10.1).
4. Use 2 wrenches when connecting field piping to units.
5. Provide a sediment trap before each unit and in the line
where low spots cannot be avoided (see Figure 10.1).
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.
10
Figure 10.1 - Recommended Sediment Trap/Manual
Shut-off Valve Installation for Gas Connection
Manual shut-off valve is in the "OFF" position when handle is perpendicular
j
to pipe.
Table 10.1 - Sea Level Manifold Pressure & Gas
Consumption j
Manifold Pressure
Model Size
("W.C.)
150 Gal/Hr. Propane
Orifice Drill Size
175 Gal/Hr. Propane
Orifice Drill Size
200 Gal/Hr. Propane
Orifice Drill Size
250 Gal/Hr. Propane
Orifice Drill Size
300 Gal/Hr. Propane
Orifice Drill Size
350 Gal/Hr. Propane
Orifice Drill Size
400 Gal/Hr. Propane
Orifice Drill Size
Table 10.2 - Gas Pipe Capacities - Natural Gas
Pipe
Length (ft)
1/2"
10
132
20 92
30 73
40 63
50 56
60
50
70 46
80 43
100 38
125 34
150 31
j 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.
k For pipe capacity with propane gas, divide natural gas capacity by 1.6.
Example: What is the propane gas pipe capacity for 60' of 1-1/4" pipe? The
natural gas capacity is 400 CFH. Divide by 1.6 to get 250 CFH for propane
gas.
6-580.18
j
Natural Propane
3.5 10
CFH 138.1 58.0
- 1.64
21 39
CFH 166.7 70.0
- 1.86
28 43
CFH 190.5 80.0
- 2.19
25 42
CFH 238.1 100.0
- 2.74
18 36
CFH 285.7 120.0
- 3.29
21 39
CFH 333.3 140.0
- 3.84
23 41
CFH 381.0 160.0
- 4.38
25 42
Natural Gas
3/4" 1" 1-1/4" 1-1/2"
278 520 1050 1600
190 350 730 1100
152 285 590
130 245 500
115 215 440
105 195 400
96 180 370
90 170 350
79 150 305
72 130 275
64 120 250
# of
Orifices
2
3
3
3
4
5
6
jk
2"
3050
2100
890 1650
760 1450
670 1270
610 1150
560 1050
530 930
460 870
410 780
380 710