When did you last change the filter in your air/air pump or exhaust air heat pump?
The filters in your air/air pump or exhaust air heat pump should be cleaned regularly with the vacuum cleaner. At least once a year, you should also replace them to ensure that you get the maximum effect from your heat pump, but also if you have an air/air heat pump or supply air unit to ensure that you have a healthy and fresh indoor environment.
In your air/air heat pump, you must regularly vacuum the coarse filters when you clean. You should replace the particle/air improvement filters at least once a year to ensure the best indoor climate and reduce allergenic particles in the air.