Navien NFC-175, Service Manual

Page: 22 / 138

22 NFC Service Manual
Version 1.0
3. Press the Command dial ( ) to enter special operation mode.
4. Rotate the Command dial ( ) to move to 7. SH 2nd MAX ,
and then press the Command dial ( ) to select the operation
mode.
5. Press the Back button ( ) twice to return to normal operation
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.
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.
Digital pressure
manometer
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 18.