Navien NHB-055 Service Manual page 22

2. Turn on the boiler. On the front Panel, press and hold the
Diagnostics Button for over5 seconds until "1.PAR" is displayed.
3. Press the + (Up) button two times to change the display to
"3.OPR".
4. Press the Mode button once to access the Operation Mode
menu.
5. Press the + (UP) button until "MAX2" is displayed.
6. Press the Reset button twice to return to normal operation
mode.
7. Run space heating. The gas in the gas supply line will be
purged.
8. Leave the boiler on until the boiler shuts down due to lack of
gas supply, and then turn off the boiler.
9. Remove the front cover by loosening the 4 Phillips head screws
securing it to the case.
22 NHB Service Manual
MODE
10. Loosen the screws indicated in the figure below and connect a
manometer to the pressure port. Reset the manometer to zero
before use.
11. Re-open the manual gas valve and check for leaks.
12. Activate multiple zones to ramp the boiler up to its maximum
firing rate.
13. 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 17.
Digital pressure
manometer
Version 1.0