From the moment outside air enters the system, a Zehnder system (and its filters) are designed to keep air contaminants from entering your home, while efficiently recovering heat (or cooling) from the air exiting your home.
Do you know every level of filtration available to you for your Zehnder recovery ventilator? If you’ve recently installed one of these units, or purchased a house that included one already, you hopefully know of (and are changing) at least the in-unit filters. These two filters, one for supply and one for return air, do the brunt of the filtration work to keep your unit running efficiently and delivering the cleanest air, but there are a few other filters that complement the system.