1. Choose: If you want to replace the G3 coarse filters more often than the F7 cassette filters, instead of ordering just the filterset, choose the option: Filterset + 2 extra pcs of G3 coarse filters. This way you add two coarse filters, that are needed for an extra change, to your order.
The recommended interval for filter changes is 2–3 times a year. In connection to the filter replacement, clean the ventilation unit and remove possible loose dirt, for example by using a vacuum cleaner. You should also check the condition of the heat exchanger and clean it if necessary with suitable detergent.