Navien NPE Installation & Operation Manual page 22

Maximum Liquefied Propane Delivery Capacity
In Thousands of BTU/H (0.5 in WC Pressure Drop)
Length (including fittings)
Pipe Size
10 ft 20 ft
(3 m) (6 m)
1 / in 291 200
2
3
/ in 608 418
4
1 in 1,150 787
1 1 / in 2,350 1,620
4
1 1 / in 3,520 2,420
2
2 in 6,790 4,660
3.3.2 Measuring the Inlet Gas Pressure
WARNING
The water heater 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 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
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 gas supplier or a qualified
Note
installer to supply proper gas pressure to the unit.
To measure the inlet gas pressure:
1. Shut off the manual gas valve on the gas supply line.
22 Installing the Water Heater
30 ft 40 ft 50 ft 60 ft
(9 m) (12 m) (15 m) (18 m)
160 137 122 110
336 287 255 231
632 541 480 434
1,300 1,110 985 892
1,940 1,660 1,480 1,340
3,750 3,210 2,840 2,570
1
/ psi (3.5 kPa). The appliance must be isolated from the gas supply piping system by closing its
2
Gas Valve
80 ft 100 ft 125 ft
(24 m) (30 m) (38 m)
101 94 89
212 197 185
400 372 349
821 763 716
1,230 1,140 1,070
2,370 2,200 2,070
Opened Closed
150 ft 175 ft 200 ft 250 ft
(45 m) (53 m) (60 m) (76 m)
84 74 67 62
175 155 140 129
330 292 265 243
677 600 543 500
1,010 899 814 749
1,950 1,730 1,570 1,440
1
/
2
psi