Navien NPN Installation & Operation Manual page 24

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
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
If gas pressure is out of the acceptable range or an excessive pressure drop is observed, contact the
Note
gas supplier or qualified 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.
/ psi (3.5 kPa). The appliance must be isolated
1
2
/ psi (3.5 kPa).
1
2
Opened Closed
Gas Valve
Installing the Water Heater 23