we have two furnaces/ac's one up stairs and one downstairs. The filters in the downstairs unit get dirty faster than the ones upstairs. We thought about some sort of extra filter system, but if we run the vacuum every other day, the filter doesn't get as bad. We run the vacuum just about that often anyway because of the German Shepherd. The other dogs aren't shedders. (he also gets brushed out side twice a week)
There is no heat or ac in the basement, it is cut off from the rest of the house. I use a dust collector down there in the shop.