Navien NP Condensing Tankless Gas Water Heater - Service Manual

5.7. 09Error
Error occurrence conditions and check items.
Error
09E
Fan motor
RPM error
Description
The system checks the RPM signal after the blower starts to run, and displays
the error message 09E (cleared manually) in the following cases:
1. If the RPM signal is 400 or lower at pre-purge, the system repeats pre-purge
10 times. If the RPM remains 400 or lower, the system determines RPM error,
and the boiler switches into Lock-Out (gas valve and ignition transformer locked).
(However, the air volume sensor should be normal.)
2. If the RPM signal of 400 or lower is detected for 3 seconds during combustion,
the system stops combustion, and the boiler switches into Lock-Out. (However,
the air volume sensor should be normal.)
3. If the pre-purge RPM signal of 400 or lower is detected, and the voltage of the air
volume sensor is lower than the standard voltage (ignition voltage), the system
de-termines RPM error, and the boiler switches into Lock-Out.
Check items
1. Check if the blower works normally.
2. check the power supply to the blower (Black + Red, approx. DC 127~184 V)
3. If RPM is significantly low while the blower works and the power supply is normal,
replace the blower.
4. If the blower connector is wet due to any reason including leakage, take the
corrective action.
5. Check for loose connection of white tower on PCB
©Navien America Inc. 2010
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NR/NP series service Manual
Version 2.0