My Philips Air Humidifier does not reach the target level

The room is too big: If the room your humidifier is located in exceeds the maximum capacity for the appliance, your humidifier will not be able to reach the desired humidity level. Please see below for information regarding the maximum room size for your model:
HU4803- 25 m2
HU4811- 38m2
HU4813- 44 m2
HU4814- 40m2
If the room size exceeds the capacity of your appliance, please consider buying a second humidifier.
Doors or windows are open: When windows or doors are open, the humidity from your Philips humidifier will not remain in the room.
To resolve this issue, please ensure that windows and doors are closed when the humidifier is in operation.
New furniture has been added to the room: New furniture can absorb the moisture provided by the Philips Air Humidifier, and this can prevent the humidity in the room reaching the target level. Allow the humidifier to run for a longer period in order to resolve this issue.
The indoor temperature is much warmer than outdoors: Central heating systems may limit the ability of your humidifier to reach the desired level of humidity, by drying the air during the heating process.
Normal behavior of the software algorithm: The display on your Philips Air Humidifier increases by 1 RH per second. Therefore it may take some time for larger changes in humidity to be reflected on the display.

The room is too big