Navien NCB-150E Service Manual page 24

5. Loosen the screws indicated in the figure below and connect a
manometer to the pressure port. Reset the manometer to zero
before use.
6. Re-open the manual gas valve and check for leaks.
7. Open multiple fixtures that have high flow rates, such as
bathtub and shower faucets, to ramp the boiler up to its
maximum firing rate.
8. 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.
Digital pressure
manometer
NOTE
For NCB series, remove
the boiler front cover by
loosening the 4 Phillips head
screws securing it to the
case.
System Details 23