Navien NCB-180 Installation & Operation Manual page 36

2. Open a hot water faucet. The boiler should turn on and the gas
in the gas supply line will be purged.
3. Leave the faucet on until the boiler shuts down due to a lack of
gas supply, and then turn off the hot water faucet.
4. Remove the front cover by loosening the 4 Phillips head screws
securing it to the case.
CAUTION
Ensure that no cables are in the way before folding down the
PCB assembly. If the assembly is stuck, do not force it. Doing
so may damage the cables and result in serious malfunctions.
Check again to ensure that no cables or any other parts are in
the way before you proceed.
5. 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
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 8.
Connecting the Gas Supply 35