Navien NHB-055, Руководство по обслуживанию

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90 NHB Service Manual Version 1.0
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.
●
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.
●
Or use a multi-meter to measure the flame sensing current (normally over 3~4 μA).
Measuring flame current Grounding wire position
Flame loss and
noise occurs at
ignition
Check if there are any
blockages in the gas
orifice plate.
Ignition failure will occur if the gas orifices are clogged.
●
Remove the gas inlet pipe and check the orifice plate.
Improper air
intake air supply
Rainwater intrusion Check if rainwater has collected inside the unit from an improperly installed air intake pipe.
Other trouble
Screw loosening Tighten the ground connection screws on heat exchanger.
Defective PCB If the issue continues despite checking above items, replace the PCB.