Stadler Form humidifier displays an 'F' or filter icon and stops or reduces output

Safety: Unplug the humidifier before servicing. Water and electricity can be dangerous together.

• Clean or replace filter: Remove the water tank and access the evaporative filter cassette (for models like Oskar). If the filter is brown, stiff, or has heavy mineral buildup, replace it with a genuine Stadler Form filter. Do not attempt to scrape off scale; this damages the media.
• Rinse housing: Clean the filter tray and housing with warm water and a soft cloth. Avoid harsh chemicals that can damage plastic.
• Reset reminder: After replacing the filter, reset the filter timer according to the user manual (often by holding a specific button for several seconds until the icon clears).
• Check airflow: Vacuum the intake and outlet grilles to remove dust that can reduce performance.