Navien NPE-180A Installation Manual page 19

Maximum Liquefied Propane Delivery Capacity
in Thousands of BTU/H (0.5" WC Pressure Drop)
Length (including fittings)
Pipe Size
10' 20'
(3m) (6m)
1/2" 291 200
3/4" 608 418
1" 1,150 787
1 1/4" 2,350 1,620
1 1/2" 3,520 2,420
2" 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" and 10.5" WC for natural gas and between 8.0" and 13" 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).
To measure the inlet gas pressure:
1. Shut off the manual gas valve on the gas supply line.
18 Installing the Water Heater
30' 40' 50'
(9m) (12m) (15m)
160 137 122
336 287 255
632 541 480
1,300 1,110 985
1,940 1,660 1,480
3,750 3,210 2,840
Gas Valve
60' 80' 100'
(18m) (24m) (30m)
110 101 94
231 212 197
434 400 372
892 821 763
1,340 1,230 1,140
2,570 2,370 2,200
Opened Closed
125' 150' 175'
(38m) (45m) (53m)
89 84 74
185 175 155
349 330 292
716 677 600
1,070 1,010 899
2,070 1,950 1,730
200' 250'
(60m) (76m)
67 62
140 129
265 243
543 500
814 749
1,570 1,440