Navien NFB-175H User's Information Manual page 19

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 6 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,
Note
●
test for proper 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
Note
at least once 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.
Maintaining the Boiler 19