Navien NFB-301C User's Information Manual page 15

Checking the Water System
1. Verify all system components are correctly installed and
operational.
2. Check the cold fill pressure for the system. Verify it is correct
(must be a minimum of 12 psi).
3. Watch the system pressure as the boiler heats up (during
testing) to ensure pressure does not rise too high.
If the system contains glycol, test for proper
Note
concentration as recommended by manufacturer.
Excessive pressure rise indicates expansion tank
sizing or performance problem.
4. Inspect automatic air vents and air separators. Remove air vent
caps and briefly press push valve to flush vent.
5. Replace caps. Make sure vents do not leak. Replace any leaking
vents.
Checking Expansion Tank
Expansion tanks provide space for water to move in and out as
the heating system water expands due to temperature increase
or contracts as the water cools.
Perform annual checks as recommended by manufacturer to
ensure proper operation.
Checking the Pressure Relief Valves
1. Inspect the relief valve and lift the lever to verify flow. Before
operating any relief valve, ensure that it is piped with its
discharge in a safe area to avoid severe scald potential.
Safety relief valves should be inspected at least once
Note
every three years, by a licensed plumbing contractor
or authorized inspection agency, to ensure that the
product has not been affected by corrosive water
conditions and to ensure that the valve and discharge
line have not been altered or tampered with illegally.
WARNING
Certain naturally occurring conditions may corrode the
valve or its components over time, rendering the valve
inoperative. Such conditions are not detectable unless
the valve and its components are physically removed and
inspected. This inspection must only be conducted by a
plumbing contractor or authorized inspection agency – not
by the owner. Failure to re-inspect the boiler relief valve
as directed could result in unsafe pressure buildup, which
can result in severe personal injury, death, or substantial
property damage.
Following installation, the valve lever must be operated at
least once a year to ensure that waterways are clear. Certain
naturally occurring mineral deposits may adhere to the valve,
rendering it inoperative. When manually operating the lever,
water will discharge and precautions must be taken to avoid
contact with hot water and to avoid water damage.
Before operating lever, check to see that a discharge line
is connected to this valve directing the flow of hot water
from the valve to a proper place of disposal. Otherwise
severe personal injury may result. If no water flows, valve is
inoperative. Shut down the boiler until a new relief valve has
been installed.
2. After following the above warning directions, if the relief
valve weeps or will not seat properly, replace the relief valve.
Ensure that the reason for relief valve weeping is the valve and
not over-pressurization of the system due to expansion tank
waterlogging or undersizing.
Inspecting the Ignition and Flame Detector Electrodes
1. Remove the ignition and flame detector electrodes from the
boiler heat exchanger.
2. Remove any deposits accumulated on the ignition/flame
detector electrode. If the electrodes cannot be cleaned
satisfactorily, replace with new ones.
3. Replace ignition/flame detector electrode, making sure gasket
is in good condition and correctly positioned.
Maintaining the Boiler 15