60 Connecting the Gas Supply
Maximum Liquefied Propane Delivery Capacity
In Thousands of BTU/H (0.5 in WC pressure drop)
Pipe
Size
Length (including fittings)
10 ft
(3 m)
20 ft
(6 m)
30 ft
(9 m)
40 ft
(12 m)
50 ft
(15 m)
60 ft
(18 m)
80 ft
(24 m)
100 ft
(30 m)
125 ft
(38 m)
150 ft
(45 m)
175 ft
(53 m)
200 ft
(60 m)
250 ft
(76 m)
1
/
2
in
291
200
160
137
122
110
101
94
89
84
74
67
62
3
/
4
in
608
418
336
287
255
231
212
197
185
175
155
140
129
1 in
1,150 787
632
541
480
434
400
372
349
330
292
265
243
1
1
/
4
in 2,350 1,620 1,300 1,110 985
892
821
763
716
677
600
543
500
1
1
/
2
in 3,520 2,420 1,940 1,660 1,480 1,340 1,230 1,140 1,070 1,010 899
814
749
2 in
6,790 4,660 3,750 3,210 2,840 2,570 2,370 2,200 2,070 1,950 1,730 1,570
1,440
4.2 Measuring the Inlet Gas Pressure
WARNING
The boiler cannot function properly without sufficient inlet gas pressure. Measuring the inlet gas pressure
should be performed by a licensed professional only.
●
The inlet gas pressure must be maintained between 3.5 in and 10.5 in WC for natural gas and between 8.0 in
and 13.0 in WC for liquefied propane.
●
The appliance and its individual shutoff valve must be disconnected from the gas supply piping system during
any pressure testing of that system at test pressures in excess of
1
/
2
psi (3.5 kPa).
●
The appliance must be isolated from the gas supply piping system by closing its individual manual shutoff
valve during any pressure testing of the gas supply piping system at test pressures equal to or less than
1
/
2
psi
(3.5 kPa).
Note
If gas pressure is out of the acceptable range or an excessive pressure drop is observed, contact the
gas supplier or a qualified installer to supply proper gas pressure to the unit.
Summary of Contents for NFC-250/175H
Page 67: ...67 Venting for Combustion Air WARNING The vent installation detector Detectable Undetectable...
Page 149: ...Memo...
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