Nordmann Engineering MinAir Operating Instructions Manual page 12

During the start-up phase, or after a new replacement cylinder has been fitted, the maximum water level can be
attained. When the maximum water level has been reached, the inlet valve closes briefly; this is a normal occurrence
during the steam cylinder concentration phase. The length of this phase can vary; it lasts until the cylinder has reached
the nominal rating. It can be examined by pressing button T1 twice at any time (see chapter 5.2)
5.4 Servicing and system messages
The electronic control unit with microprocessor continuously monitors the operation of the MinAir. Eventually
deviations from the operating condition (U-codes) will be shown on the display.
Code Code "U1" is a servicing signal.
''U1'' The steam cylinder can no longer attain the nominal output and needs, therefore, to be cleaned or perhaps replaced
(refer to chapter 6.3). Code "U1" is a purely servicing code. The unit does not switch off automatically and the
humidifier continues to function at a reduced output. Acknowledgment is affected by the reset procedure.
Code Message ''excess current''
''U2'' Whenever there is excess current (140% of the nominal value) during normal operations, the humidifier switches its
steam production off automatically for safety reasons. After the fault has been rectified, the humidifier is put back into
operation by pressing T1.
Code The humidifier tries to fill the steam cylinder, without reaching the required steam capacity.
''U3'' Possible causes are interrupted water supply, a defective contactor relay or inlet valve, or overpressure in the steam line
for eg. due to kinked steam hose. The humidifier switches itself off automatically after 30 minutes. After the fault has
been rectified, the humidifier is put back into operation by pressing T1 (arrow upwards).
Code Micro controller displays no code.
''U4'' This signal appears if a replacement electronic control unit has been fitted to the humidifier without being code, which
prevents the humidifier from operating. The signal disappears as soon as the electronic controls unit has been coded
according to the settings shown on the coding sticker inside the unit.
5.5 Safety functions
NORDMANN humidifiers are protected against running dry, i.e. the power is cut off automatically as soon as the
electrodes in the steam cylinder protrude above the water level.
If current consumption becomes excessive (25% above the nominal level), the outlet valve is opened automatically.
Because the electrodes are then in contact with less water, current consumption falls back to the nominal value.
If current fails to fall below 140% of the nominal level, even after several drainage operations, the humidifier turns
itself off automatically and the failure message "U2" appears on the LED display.
5.6 Remote indication
A standard, potential-free relay output enables the alarm messages U1, U2 and U3 to be remotely displayed.
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