Measuring The Inlet Gas Pressure - Navien NFC-250/175H Installation Manual

Maximum Liquefied Propane Delivery Capacity
In Thousands of BTU/H (0.5 in WC pressure drop)
Length (including fittings)
Pipe
10 ft 20 ft 30 ft
Size
(3 m) (6 m) (9 m)
/ in 291 200 160
1
2
/ in 608 418 336
3
4
1 in 1,150 787 632
1 / in 2,350 1,620 1,300 1,110 985
1
4
1 / in 3,520 2,420 1,940 1,660 1,480 1,340 1,230 1,140 1,070 1,010 899
1
2
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

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
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
(3.5 kPa).
If gas pressure is out of the acceptable range or an excessive pressure drop is observed, contact the
Note
gas supplier or a qualified installer to supply proper gas pressure to the unit.
60 Connecting the Gas Supply
40 ft 50 ft 60 ft 80 ft
(12 m) (15 m) (18 m) (24 m)
137 122 110 101
287 255 231 212
541 480 434 400
892 821
100 ft 125 ft 150 ft 175 ft
(30 m) (38 m) (45 m) (53 m)
94 89 84 74
197 185 175 155
372 349 330 292
763 716 677 600
/ psi (3.5 kPa).
1
2
200 ft 250 ft
(60 m) (76 m)
67 62
140 129
265 243
543 500
814 749
1,440
/ psi
1
2