Since humidifiers are only used in the winter there are two times per year that they need attention. One is at the beginning of summer and the other is at the beginning of winter.

In the winter, the water panel should be changed. When you change the water panel, make sure the panel is in proper direction so the water will flow inward and not outward. Flowing outward can cause the humidifier to leak. Check for a marking on the top of the water panel to indicate which side is the top of the panel.

Check the drain line to make sure the water can flow freely to a drain.

Check that the water access to the humidifier is on, and the damper to the humidifier is on.

Set the humidistat and the water should start flowing. You can check this when the heat is on. Remove the drain to visually see the water flowing.  

In the summer, close off the air damper and water to the humidifier.