I have noticed long before my adventures with coal heat that filtering the house air has many health advantages for me. this is one of the many reasons why I choose a ducted whole house air system as I can estimate total changes per hour and the filtration level I want. Of course it can be done by hydronics or even a simple fire place but to filter the house becomes an additional consideration. The subject of filtration efficiency has been covered elsewhere on this forumHow to connect cold air return to Koker
and other examples. I used to have a winter hacking cough that only went away when I used a MERV 11 filter or better. What I love about the LL Anthraking as I start to get it set up now is the 1800CFM squirrel cage fan and the way it is integrated into the coaltrol (smooth as butta). There is an input with provision for a 20x20" 1" filter on which I was planning to put a Filtrete 1900 (about MERV 12). As I spent about 10 years in pharmaceutical clean room operations using filters which were about MERV 20 (expressed differently then and now), I was aware of the desirability of the more the better filtration systems. Now in dirty homes (comparatively) you reach the point of diminishing returns but sucking some bacteria and other fumes and smoke even unattached viruses has many health advantages. I pay $20 per filter and in about a week it is dirty. So 4" filters, prefilters other ideas are appropriate here. Any comments.