Navien NP Condensing Tankless Gas Water Heater - Service Manual

5.8. 10Error
Error occurrence conditions and check items.
Error
10E
Air pressure
error
Description
The system senses the air volume and the RPM signal, and displays 10E on the
indoor thermostat in the following cases:
1. During pre-purge
If the air volume sensor voltage fails to reach the standard voltage (ignition voltage),
while the FAN RPM signal is sensed, the system retries pre-purge. If the air volume
sensor voltage fails to reach the standard voltage after 10 continuous prepurge
actions, the system determines the air pressure error (or the air pressure hose error),
and the boiler switches into Lock-Out.
2. During combustion of boiler
If the current RPM is higher than the standard RPM by 1,000 or higher, the system
determines the air pressure error (excessive air pressure),
and stops the combustion process. The boiler switches into Safety-Shutdown,
and runs the fan continuously. If the current RPM becomes within the standard
RPM ±500, the system cancels the error, and returns to the standby mode.
Check items
1. If the error occurs intermittently, replace the controller with a new model (324-7M).
2. Check the air pressure hose (visual inspection on tear and hole, and water remained
in the hose after installation).
3. Check if the venture (burner) hole is clogged.
4. Check if the condensed water hose or the drain is clogged.
5. Check the flue and exhaust environment. (Inflow of exhaust gas generates noise.)
6. Check if the air supply/exhaust flue is clogged (rainwater collected due to dent or
downward installation).
7. Defective air pressure sensor or PCB.
©Navien America Inc. 2010
84
NR/NP series service Manual
Version 2.0