Navien NR-21DU, Manual

Page: 26 / 36

About errors and icons
Depending on the severity of the issue that is
causing the error, the water heater will either stop
its operation or will only be able to perform basic
operations. A flashing red LED and error icon can
be seen on the remote controller along with the
associated error code.
The error code is displayed in 3 digits. (see below).
Reset errors
After the problems that are causing the errors are
resolved, press the OK button once and "RST" will
be displayed on the LCD display.
For Cascade systems
Regardless of error levels, the following is
displayed in turn: Current status, error code, and
Cascade ID.
You can reset errors manually in order to allow the
water heater to continue operation.
26
About scale warning
Scale warning
When the water heater needs to be cleaned, the
scale alarm is activated.
Current status and scale alarm code is displayed.
You can change the scale warning intervals if
desired.
Deactivating the scale alarm
Press and hold the OK button for 2 seconds.
"RST" is displayed for 3 seconds.
For Cascade systems
The following is displayed in turn:
Current status, alarm code, and Cascade ID.
You can change the settings and control them.
Note For details, see the Operation manual.