To ensure that your HRV system continues to operate effectively it is important that it is maintained. An important part of this maintenance is cleaning and replacing the filters in your unit to ensure that air quality and airflow are not reduced.
Most ventilation manufacturers recommend that filters be changed at least once a year, but this is subject to where you live and the conditions of air quality around your home.
If you live in a town or city or beside a busy road, air pollution tends to be greater so your ventilation filters will need to be cleaned and changed more often.
Best practice is to check and clean your ventilation filters every 3 months.