Vertiv™ | Liebert® AHU | User Manual
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9. Use temperature and humidity measuring meters with higher precision to measure and calibrate the temperature and
humidity sensors.
10. Adjust the setpoints. Check the action of the functional parts and the auto-flush control logic of the water pan of the
infrared humidifier according to control logic.
11. Simulate and check the operation of the protection devices including high and low-pressure alarms, high and low
temperature alarms, high water level alarms and over-temperature protection.
12. Check the water detection sensor. Bridge the water detection sensor probes and confirm the alarm through the
controller. The sensor should be placed in low-lying areas near the unit.
Note: Set the humidity control mode to ‘relative humidity control during calibration process.
1. Before fastening the connection of any mechanical parts or cables, ensure that the power supply
of the control unit has been disconnected.
2. Do not use the water detection sensor adjacent to flammable liquid or use it to detect flammable
liquid.
5.6. Filter Maintenance Guide
To ensure efficient operation, the dust filter must be checked once a month, and replaced as required. The filter clogging
switch and pressure difference switch are located. You need to adjust the set point of the filter clogging switch if the new
filter is of a different model. It samples the air pressures from the front and behind the filter through a black hose and decides
the output after comparing the two values.
To adjust the setting point of the filter clogging switch, you should:
1. After replacing the filter, restore and seal all the panels, so that the alarm point can be found precisely.
2. Keep the fan running and rotate the rotary switch of the filter clogging switch counter-clockwise until the filter alarm is
triggered.
3. Rotate the rotary switch clockwise for two and a half rounds or rotate it to the point where the filter should be replaced.
Note: 1. Cut off the power supply before replacing the filter.
2. It is recommended to set airflow switch according to the manual instructions, otherwise there will be an air filter alarm
or in the opposite case, the alarm could not be triggered by the dust accumulation on the filter, endangering the system
operation due to deteriorated ventilation.
3. If you are unsure about the setting point, consult with Vertiv before using a filter of a different model to replace the old
one.
