Gas Connections - Modine Manufacturing MPR Series Installation And Service Manual

GAS CONNECTIONS

W.C. for propane gas and should not drop below 6.0" W.C.
when the unit is operating. When sizing the inlet gas pipe
diameter, make sure that the unit supply pressure can be
met after the 0.3" or 0.5" W.C. has been subtracted. If the
pressure drop is too high, refer to NFPA 54 National Fuel
Gas Code for other pipe capacities.
3. The gas piping is to enter the unit from the side (refer to
the unit dimensions). B- and C-Cabinet sized units include
a hole and grommet in the side of the casing for side gas
piping entry. D-Cabinet sized units include two holes with
grommets for side pipe entry. Install a ground joint union
with brass seat and a manual shut-off valve external of the
unit casing, and 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). Verify the manual shut-off valve is gas tight
on an annual basis.
4. Provide a sediment trap before each unit in the line where
low spots cannot be avoided (see Figure 11.1).
5. 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
GAS
SUPPLY LINE
GAS
SUPPLY LINE
3"
MIN.
SEDIMENT
TRAP
Valve is in the "OFF" position when handle is perpendicular to pipe.
j
GROUND JOINT
UNION WITH
BRASS SEAT
MANUAL GAS 
SHUT-OFF VALVE
TO GAS
CONTROLS
PLUGGED
1/8" NPT TEST
GAUGE CONNECTION
Table 11.1 - Gas Heating Piping Connection Sizes
Cabinet Size Gas Type
(Digit 6) (Digit 17) j
Natural Gas
B
Propane (LP) Gas
Natural Gas
C k
Propane (LP) Gas
Natural Gas
D l
Propane (LP) Gas
Units with Natural Gas heating option have model nomenclature Digit 17 = 2
j
or 3. Units with Propane (LP) Gas heating option have model nomenclature
Digit 17 = 5 or 6.
C-Cabinet units consist of two furnaces that together total the value shown in
k
Table 11.1.
D-Cabinet units consist of two furnaces that together total the value shown in
l
Table 11.1 for sizes up to 800,000 Btu/hr. For sizes over 800,000 Btu/hr, the
unit consists of four furnaces that together total the value shown in Table 11.1.
Table 11.2 - Natural Gas Pipe Capacities (MBH) m
Pipe Length
(ft)
10 540
20 371
30 298
40 255
50 226
60 205
80 175
100 155
125 138
150 125
175 114
200 107
Capacities based on gas pressure up to 14" W.C. through Schedule 40 pipe
m
with a pressure drop of 0.3" W.C. for Natural gas with a specific gravity of 0.60.
Table 11.3 - Propane Gas Pipe Capacities (MBH) n
Pipe Length
(ft)
1"
10 1,150
20 787
30 632
40 541
50 480
60 434
80 400
100 372
125 349
150 330
175 292
200 265
Capacities based on gas pressure up to 14" W.C. through Schedule 40 pipe
n
with a pressure drop of 0.5" W.C. for Propane gas with a specific gravity of
1.50.
Example:
A D-Cabinet unit with Digit 17=2 (Natural Gas) and Digit 18=Q (800MBH)
is installed in a location requiring 50 feet of gas supply pipe. What is the
minimum pipe diameter required for the supply pipe?
From Table 11.2, 50 feet of 1-1/2" pipe has a capacity of 695MBH which may
result in too significant of a pressure drop. The 2" pipe has a capacity of
1,344MBH which is sufficient for a unit with an 800MBH Natural Gas heat option.
MCP15-500.9
Furnace Size
(MBH)
Below 200
200 and Larger
Below 300
300 and Larger
All
All
Below 850
850 and Larger
All
Nominal Gas Pipe Diameter
1" 1-1/4" 1-1/2"
1,113 1,659
762 1,145
612 917
524 784
464 695
420 630
360 540
319 478
282 423
256 384
235 353
219 329
Nominal Gas Pipe Diameter
1-1/4" 1-1/2"
2,350 3,520
1,620 2,420
1,300 1,940
1,110 1,660
985 1,480
892 1,340
821 1,230
763 1,140
716 1,070
677 1,010
600 899
543 814
Gas Connection
Size
1/2"
3/4"
1/2"
3/4"
1"
3/4"
1" (Qty 2)
1-1/2" (Qty 2)
1" (Qty 2)
2" 2-1/2"
3,203 5,103
2,195 3,507
1,764 2,814
1,512 2,405
1,344 2,132
1,218 1,932
1,038 1,659
921 1,470
816 1,302
739 1,176
680 1,082
632 1,008
2" 2-1/2"
6,790 10,800
4,660 7,430
3,750 5,970
3,210 5,110
2,840 4,530
2,570 4,100
2,370 3,770
2,200 3,510
2,070 3,290
1,950 3,110
1,730 2,760
1,570 2,500
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