Navien NCB-150E, Руководство по обслуживанию, Страница: 95 / 157

Version 1.4 94 NCB-E Service Manual
Failure mode Cause Check method
Repeated ignition-out
Flame sensing error
1. Check the location of the flame, if there is any deformation or foreign substance,
repair or replace the part.
2. Check the flame rod wire for proper connection and/or damage.
3. Check the grounding to the boiler case to verify proper grounding at the outlet.
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If the ground wire is improperly connected or not making a good connection,
remove and reattach the ground wire ensuring good contact with the case.
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Or use a multi-meter to measure the flame sensing current (normally 3-4 µA).
Measuring flame current Grounding wire position
Screw loosening
Tighten the ground connection screws on heat exchanger.
Flame Rod (Electrode)
Replace the electrode or clean the fire detecting electrode.
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Cause: Due to the properties of the electrode, the oxide film is created due to long-
term exposure to the high temperature; therefore, errors may be caused in detecting
the fires.
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Check-up: Use sandpaper to clean the fire detecting electrode covered with oxide
film or replace it.