Gas Connections - Modine Manufacturing MT28 Installation And Service 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 unit controls must never exceed 14"
W.C. (1/2 psi).
3. To prevent flame bail-out from the heater, the gas input
to the appliance as indicated on the serial plate, must not
exceed the rated input by more than 5% or fall below the
rated input by more than 5%.
1. Installation of piping must conform with local building
codes, or in the absence of local codes, of the National
Fuel Gas Code, ANSI Z223.1 (NFPA 54) - Latest Edition. In
Canada, installation must be in accordance with CAN/CGA-
B149.1 for natural gas units and CAN/CGA-B149.2 for
propane units.
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 7.1 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 5.1. 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 5.1
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 7-14" 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 Engineers
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
Table 5.1
Gas Pipe Capacities
Length
Of Pipe 1/2"
(feet) Natural Propane Natural
10 132 83
20 92 58
30 73 46
40 63 40
50 56 35
60 50 32
70 46 29
80 43 27
90 40 25
100 38 24
125 34 21
150 31 20
Gas Pipe Capacities (Up to 14" W.C. Gas Pressure through Schedule 40 Pipe)
Cubic Feet per Hour with Pressure Drop of 0.3" W.C.
Natural Gas Specific Gravity – 0.60, Propane Specific Gravity – 1.50
3/4"
Propane Natural Propane
278 175
190 120
152 96
130 82
115 72
105 66
96 60
90 57
84 53
79 50
72 45
64 40
plugged tapping immediately upstream of the gas supply
connection to the heater, accessible for test gauge
connection. See Figure 5.1.
4. Installation of a sediment trap in the gas supply line before
each unit is required to minimize the possibility of loose
scale or dirt within the gas supply line entering the heater
gas control system. See Figure 5.1.
5. An approved flexible connector may be used (local codes
permitting) as a convenient method of connecting the
heaters to the gas supply and to avoid placing stress on
the gas supply line.
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 5.1
Recommended Sediment Trap/Manual Shut-Off Valve
Installation
GAS
SUPPLY LINE
MIN.
Pipe Diameter
1" 1-1/4"
Natural
520 328 1050
350 221 730
285 180 590
245 154 500
215 135 440
195 123 400
180 113 370
170 107 350
160 101 320
150 95 305
130 82 275
120 76 250
GAS
SUPPLY LINE
MANUAL GAS
SHUT-OFF VALVE
PLUGGED
3" 1/8" NPT TEST
GAGE CONNECTION
SEDIMENT
TRAP
1-1/2"
Propane Natural Propane Natural Propane
662 1600 1008
460 1100 693
372 890 561
315 760 479
277 670 422
252 610 384
233 560 353
221 530 334
202 490 309
192 460 290
173 410 258
158 380 239
GROUND
JOINT
UNION
W/ BRASS
SEAT
TO
CONTROLS
2"
3050 1922
2100 1323
1650 1040
1450 914
1270 800
1150 725
1050 662
990 624
930 586
870 548
780 491
710 447
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