Hello all! In the last year or so, my wife has developed some serious allergies resulting in several sinus infections. We live in an industrial style loft and there is no shortage of dust (we also have two dogs but they are staying). We tend to notice that our unit is fairly dry and we notice a lot of dust. Our HVAC ducts were cleaned last year and there wasn't a whole lot in the ducts themselves prior to cleaning (such as construction debris etc that is common). We currently use the Filtrete Ultra allergen filters in our air exchange and we have an ionic purifier set up right by my wifes side of the bed. My question is, aside from a forced air HEPA filter unit (which we are also currently researching, recommendations are welcome!) can I add further filtering onto our HVAC unit? The Air Return is located in a closet and there is a louvered section on the door. What I am thinking is attaching a second furnace air filter to the inside of the door to act as sort of a pre cleaning filter so the air going into the air return is pre cleaned. I would more than likely put a higher flow (less intense) filter on the door and continue to use the Ultra Allergen filter in the air return itself. My common sense is telling me that this will help, but my engineering background is telling me that this will result in possible increased wear and tear on our HVAC unit.