Navien NFC-250/175H Quick Installation Manual Download Page 4

4

STEP 3  After Installing

  Opening All the Valves

 

>

 

Gas Valve

Space Heating System Valves

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2

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26

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Gas Valve

Opened

Closed

Shut-off 
valves

Power ON

Adjust Temperatures

View Basic Information

Resetting the Boiler

Space Heating Temperature

DHW Temperature

1.  In normal operation mode, rotate 

the Command dial (

). The space 

heating temperature (

) is 

highlighted on the screen.

2.  Rotate the Command dial (

) to 

the right to select the DHW 
temperature.

3.  Press the Command dial (

) to 

select the indirect DHW 
temperature (

). The highlighted 

section will flash.

4.  Rotate the Command dial (

)

 

to 

the right or left to increase or 
decrease the temperature.

5.  Press the Command dial (

) to 

confirm the new temperature.

6.  Press the Back button (

) to 

return to normal operation mode, 
or rotate the Command dial (

to adjust other operation 
conditions.

To turn the boiler on, press the 
Power button (

).

When the power is on, the boiler 
automatically enters normal 
operation mode, and the boiler’s 
operating conditions are displayed 
on the screen.

Note

The setup wizard should 
run the first time the unit 
is powered on. The wizard 
must be completed 
before the boiler can be 
used. Refer to page 108 in 
the Installation & 
Operation Manual.

1.  In normal operation mode, rotate the 

Command dial (

). The space 

heating temperature (

) is 

highlighted on the screen.

2.  Press the Command dial (

)

 

to select 

the space heating temperature. The 
highlighted section will flash.

3.  Rotate the Command dial (

)

 

to the 

right or left to increase or decrease 
the temperature.

4.  Press the Command dial (

)

 

to 

confirm the new temperature.

5.  Press the Back button (

) to return 

to normal operation mode, or rotate 
the Command dial (

) to adjust 

other operation conditions.

1.  Press the Menu button (

), and 

then select “1. Status 
Information”.

2.  Rotate the Command dial (

to 

switch between the information 
items.

If an error message appears during 
boiler operation, reset the boiler to 
resolve the problem. Press the Back 
button (

) on the front panel to 

reset the boiler.

Note

If resetting does not 
solve the problem, refer 
to the troubleshooting 
section of the User’s 
Information Manual or 
contact the service 
center.

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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

Digital pressure 
manometer

Shut off the manual gas valve.

Leave the faucet on until the boiler shuts down 
due to a lack of gas supply, and then turn off the 
hot water faucet.

Unfasten the 4 latches (2 at the top 
and 2 at the bottom) to remove 
the front cover and gain access to 
the internal components.

Loosen the screw indicated in the figure and 
connect a manometer to the pressure port. 
Reset the manometer to zero before use.

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5

Open

Re-open the manual 
gas valve and check 
for leaks.

Activate multiple 
zones to ramp the 
boiler up to its 
maximum firing rate.

6

NG: 3.5”–10.5” WC 
LP: 8.0”–13.0” WC

Recommended  
Gas Pressure Settings:

             When the boiler reaches its maximum firing rate,  

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 sufficient 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.navieninc.com

  Installing the Front Cover

 

>

 

  Ensure Maximum Water Flow

 

>

 

After running the boiler for the first 10 minutes, turn it off and clean the cold water filter 
and the space heating return strainer to remove any trapped debris.

  Final Check

 

>

 

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

 

 

>

 

 

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