Gas Pipe Capacities; Horizontal Venting - Two Pipes; Specific Gravity Conversion Factors - Modine Manufacturing PSH Installation And Service Manual

INSTALLATION
Horizontal Two Pipe Venting
Figure 9

Horizontal Venting - Two Pipes

1. When horizontal vents pass through a combustible wall (up
to 8 inches thick), the vent passage must be constructed
and insulated as shown in Figure 10.
2. The termination of horizontally vented system must extend
12 inches beyond the exterior surface of an exterior wall.
3. The combustion air pipe must be a minimum of 16 inches
below the vent pipe, and 24 inches from the exterior wall.
4. Support the vent and combustion air pipe as shown in
Figure 10.
Figure 10
Exhaust Vent Construction Through Combustible Walls
and Support Bracket
METAL
SLEEVE
2" MIN.
VENT PIPE
DIAMETER
METAL FACE
PLATE
METAL
SLEEVE
2" MIN.
1"
Piping
CAUTION
Gas pressure to unit heater controls must never exceed 14"
W.C. (1/2 psi).
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).
The appliance should be isolated from the gas supply piping
system by closing its field installed manual shut-off valve.
1. Installation of piping must be in accordance with local
codes, and ANSI Z223.1, "National Fuel Gas Code," or
CAN/CGA-B149 in Canada.
2. Piping to units should conform with local and national
requirements for type and volume and gas handled, and
pressure drop allowed in the line. Refer to Table 5, to
determine the cubic feet per hour (cfh) for the type of gas
FIBER GLASS
INSULATION
MIN. 2"
1"
9"
VENT TERMINATION
45 SUPPORT BRACKET
9" (where required)
(Make from 1" x 1" steel angle)
Table 2

Gas Pipe Capacities

In Cu. Ft. per Hour with Pressure Drop of 0.3 in W.C. with Specific Gravity 0.60.
Length Diameter of Pipe — Inches
of Pipe
in Ft. 1/2 3/4
15 76 218
30 73 152
45 44 124
60 50 105
75 97
90 88
105 80
120
150
180
210
240
270
300
450
600
Length Diameter of Pipe — Inches
of Pipe
in Ft. 2 3
15 2480 6500
30 1650 4700
45 1475 3900
60 1150 3250
75 1120 3000
90 930 2600
105 920 2450
120 860 2300
150 710 2000
180 720 1950
210 660 1780
240 620 1680
270 580 1580
300 545 1490
450 450 1230
600 380 1030
and size of unit to be installed. Using this cfh value and the
length of pipe necessary, determine the pipe diameter from
Table 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 2
allows for the usual number of fittings with a 0.3; W.C.
pressure drop. Where the gas supplied has a specific
gravity other than 0.60, apply the multiplying factor as given
in Table 3.
3. After threading and reaming the ends, inspect piping and
remove loose dirt and chips.
4. Support piping so that no strains are imposed on unit or
controls.
5. Use two wrenches when connecting piping to unit controls.
Table 3

Specific Gravity Conversion Factors

Multiplying factors to be used with Table 1 when the specific gravity of gas is
other than 0.60.
Natural Gas
Specific
Gravity Factor
0.55 1.04
0.60 1.00
0.65 0.962
Heater Parts from ACF Greenhouses
1 1-1/4 1-1/2
440 750 1220
285 590 890
260 435 700
190 400 610
200 345 545
160 320 490
168 285 450
158 270 420
120 242 380
128 225 350
205 320
190 300
178 285
170 270
140 226
119 192
4 6 8
12880 38700 79000
9700 27370 55850
7900 23350 45600
6800 19330 39500
6000 17310 35300
5400 15800 32250
5100 14620 29650
4800 15680 27920
4100 12240 25000
4000 11160 22800
3700 10330 21100
3490 9600 19740
3250 9000 18610
3000 8500 17660
2500 7000 14420
2130 6000 12480
Propane Gas
Specific
Gravity Factor
1.50 0.633
1.53 0.626
1.60 0.612
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