Navien NCB-180, Руководство по обслуживанию

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104 NCB Service Manual Version 1.0
5.2.13 351Error
Error conditions and Check Items
Error Description
E351
Abnormal Auto
feeder valve
If the water pressure sensor senses low water level as the heating pipe pressure is low, the system stops
operation of the boiler, and refills water automatically.
If water is supplied by auto feeder valve open over 5 minutes, the error(E351) is detected and displayed on the
front panel. If this occurs, the boiler initiates shutdown.
Check items
1. Water is not refilled.

Check if the cold water valve is closed or frozen.

Check if the auto feeder valve works normally.
2. Water overflows through condensed water hose.

Check the left drain valve of the main heat exchanger.

Check if water leaks due to a defective heat exchanger.
3. Check if water leaks from the heating pipe.
4. Check the auto feeder.
5. Check the water supplied pipe open.
6. Check the water pressure.
NO
Yes
Leaking in unit
Check leaking in unit
1. Check DHW cold water pressure
2. Check connecter
(#1,#2 and #3 of CN 22)
3. Check the water pressure sensor
Is the auto feeder valve
normal?
Yes
Replace the auto feeder valve
NO
Yes
Open the DHW cold water valve
NO
Is the DHW cold water
valve open?