My local plastic pipe dealer, who treats me with respect and honest bottom line prices, is out of 8" 3034 sewer/drain PVC. Ferguson, a national chain with knowledgeable and friendly salesmen comment that their cost is more than what I pay from this company. I have to wait a couple weeks for the next delivery and I need about 50'. But at $3.50 a foot versus $6 a foot, I can wait and have plenty to keep me occupied. However, in the interim, I have decided to bypass the indoor filter and discharge to the outside. It occurred to me that the requirements of discharge out of the blower are very different than intake into the blower. Also this will be light dust, rather than material laden air, that has been through the cyclone or Thien separator, whichever I can get to fit in my limited crawl space.
I can't think of a reason not to use HVAC uninsulated, plastic or aluminum, 8" flexible duct to discharge to the great outdoors and share my newly liberated dust, soon to be mulch, to the side garden. This is my longest run and is about 30'.
Is there any reason that I should spend the money on PVC when I don't need to worry about the duct collapsing under suction? Also, the cost between 8" and 12" HVAC flexible duct is negligible. In my small brain this would more than make up for the resistance introduced by those pesky spirals and the dreaded turbulence they introduce. The discharge on my blower is an 8"x5.5" rectangle and there are transitions that could be adapted and reinforced that would make a handy job of this. Plus there would be no fittings to fret about. I can route the duct in a gentle and pretty straight line to the wall and a cement block that is a 3 space vent that I can enlarge without worry that my home will collapse.
What am I missing? Anyone else using this stuff?