Navien NFB-175 Mode D'emploi page 50

To measure the inlet gas pressure:
1. Shut off the manual gas valve on the gas supply line.
2. Turn on the boiler. On the front panel, press the Back button (
) and the Menu button (
and then Rotate the Command dial (
Operations.
3. Press the command dial (
4. Rotate the Command dial (
then press the command dial (
mode.
5. Press the Back button (
mode.
6. Run space heating. The gas in the gas supply line will be
purged.
7. Leave the boiler on until the boiler shuts down due to a lack of
gas supply, and then turn off the boiler.
50 Connecting the Gas Supply
Opened Closed
Gas Valve
) simultaneousl for 3 seconds,
) to move to 7. Special
) to enter special operation mode.
) to move to 5. 2nd Max, and
) to select the operation
) twice to return to normal operation
8. 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.
9. Loosen the screws indicated in the figure below and connect a
manometer to the pressure port. Reset the manometer to zero
before use.
10. Re-open the manual gas valve and check for leaks.
11. Activate multiple zones to ramp the boiler up to its maximum
firing rate.
12. When the boiler reaches its maximum firing rate, check the
inlet gas pressure reading on the manometer. The gas pressure
must fall within the ranges specified on page 8.
Digital pressure
manometer