Navien NP-180 Service Manual page 92

Defective air
volume sensor
Foreign sub-stance
in the nozzle
Off at switch
of stage
Defective
multistage valve
<Multi-stage valve>
Flame blowout
Defective blower
and noise
Other trouble
Defective PCB
©Navien America Inc. 2010
<Check the differential pressure>
Flame blowout due to increased blower RPM caused by air pressure
sensor standard value error.
Replace the air pressure sensor.
The flame is extinguished due to foreign substance in the nozzle.
Defective stage-1 nozzle causes accidental fire at ignition.
Flame may be blown out if the stage is switched when the nozzles
of stages 2 and 3 are in trouble.
Disassemble the manifold and clean the nozzle.
(Remove efflo-rescence, if any, from inside wall of the nozzle)
Flame may be blown out if the stage is switched when the multi-stage
valve is defective.
Check the power supply (DC 83~120 V).
Check if the coil is disconnected.
Yellow 2P : State 2 / Red 2P : Stage 3
<Check the voltage (DC 200V)> <Check if the coil is disconnected- after plugging out the coil >
A defective proportional valve of the gas block causes trouble in
air supply during combustion.
Low gas pressure causes blowout of flame.
Thick flame causes noise and accidental fire.
If the trouble continues despite the checking of above items, replace
the PCB.
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NR/NP series service Manual Version 2.0