Navien NPE-180A Service Manual page 81

Failure mode
Ignition failure
Repeated ignition-out
80 NPE Service Manual
Cause
1. Check the primary/secondary power supply to the main gas valve.
Check, with a multimeter, if the input power is DC 22-24 V.
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2. Replace the PCB if power is not supplied.
Main gas valve
3. If power supply is normal, check if the coil is open.
4. Check if the solenoid valve works properly.
Feel or hear a click.
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Gas block Check if the coil is open
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.
Flame sensing error
3. Check the grounding to the water heater case to verify proper grounding at the
outlet.
If the ground wire is improperly connected or not making a good connection,
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remove and reattach the ground wire ensuring good contact with the case.
Or use a multimeter to measure the flame sensing current (normally 3~4 µA).
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Measuring flame current
Check method
Check the voltage of the solenoid valve /
White-Yellow , White-Red
Grounding wire position
Version 2.21