4
STEP 3 After Installing
Opening All the Valves
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Gas Valve Space Heating System Valves
Closed Open
Shut-o
valves
Power ON Turn On or O Adjust Temperatures View Basic Information Resetting the Boiler
Space Heating DHW Space Heating
Temperature
DHW Temperature
To turn the boiler on:
1. Connect the power cord. When the
power is on, the User Settings
screen is displayed.
2. Select the language you want to use
and set the vent type, current date,
and time by tapping your selections
on the screen.
3. Tap Done on the top right of the
screen to complete the settings.
To turn the Space
Heating on or o,
tap SH ON on the top
left of the screen.
To turn the DHW on or
o, tap DHW ON on the
top right of the screen.
To adjust the heating
temperature on the
screen, tap (
) or ( )
to select the space
heating temperature in
the SH Set Temp menu.
The current temperature
setting is displayed in
the menu.
To adjust the heating
temperature on the
screen, tap (
) or ( )
select the DHW Indirect
Supply temperature in
the DHW Set Temp
menu. The current
temperature setting is
displayed in the menu.
1. To view information
about the boiler, tap
the Control button
(
) > Status on the
screen.
2. Tap an item to view
the information.
Note
If resetting does not solve the problem,
refer to the troubleshooting section of
the User’s Information Manual or contact
the service center.
If an error message
appears during boiler
operation, reset the
boiler to resolve the
problem. Press and hold
the Reset button on the
front panel to reset the
boiler.
1
Open Closed
2
Open a hot water
faucet. The boiler
should turn on and
the gas in the gas
supply line will be
purged.
3
4
<NFB-301C> <NFB-399C>
Shut o the manual gas valve.
Leave the faucet on until the boiler shuts down
due to a lack of gas supply, and then turn o the
hot water faucet.
Unfasten the 4 latches (2 at the
top and 2 at the bottom) to
remove the front cover.
Loosen the screw indicated in the gure and connect a
manometer to the pressure port. Reset the manometer to zero
before use.
5
Open
Re-open the manual
gas valve and check
for leaks.
Open multiple
xtures that have
high ow rates, such
as bathtub and
shower faucets, to
ramp the boiler up to
its maximum ring
rate.
6
NG: 3.5”–10.5” WC
LP: 8.0”–13.5” WC
Recommended
Gas Pressure Settings:
<NFB-301C> <NFB-399C>
Check the inlet gas pressure reading on the manometer.
If not,
Gas supply
Adjust the inlet gas pressure with gas
regulator.
CAUTION
The boiler cannot function properly without sucient inlet gas pressure. Measuring the inlet gas pressure should be performed by a licensed professional only.
Navien, Inc.
20 Goodyear, Irvine, CA 92618
Tel: 1-800-519-8794, Fax: 1-949-420-0430
www.navien.com
Installing the Front Cover
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Ensure Maximum Water Flow
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After running the boiler for the rst 10 minutes, turn it o and clean the cold water lter
and the space heating return strainer to remove any trapped debris.
Final Check
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A trial run should be performed in accordance with the Installation checklist listed in
the boiler’s Installation & Operation Manual.
Operating the Boiler
>
Measuring the Inlet Gas Pressure
>