Cyclone Location for Outside Exhaust

[Peter Aeschliman]

All,

I'm working on the layout of my new basement shop. It's going to be an L-shaped shop, which will leave some space for our laundry and storage areas.

I'm thinking through where I should put my cyclone, knowing that I plan to vent the fine dust outside (no filters). Note my gas furnace is a sealed combustion unit, and the shop will generally be sealed from the furnace with interior walls anyway. And I will plan for make-up air. And I'll have lots of CO sensors. And I'm not worried about any neighbor situations or fine dust on the outside of the house. I've done my research on this, so let's please keep the discussion to the questions about where to locate the DC.

I have the option of placing the cyclone in a closet along an outside wall (blue box in diagram below- crude drawing not to scale)), or in a closet on the other side of the wall right at the inside corner of the L-shaped floor plan (red box below). This would put the DC much closer to my big machines (TS, Jointer/Planer combo, router table, BS, and drum sander). So the suction side of the DC runs will be much shorter and with fewer bends, with the trade off of the exhaust lines being longer to reach an exterior wall.

My thinking is that, assuming the same total length of ducting, it's better for the "suction duct" to be shorter with fewer bends and for the "exhaust duct" to be longer and more tolerant to bends. I assume this because wood chips are heavier and cause more friction inside the duct than the fine dust does, and the exhaust duct will only be carrying fines.

Is this logical or am I thinking about this wrong?

http://i66.photobucket.com/albums/h255/peteraeschliman/Basement%20Shop%20DC%20location.png (http://s66.photobucket.com/user/peteraeschliman/media/Basement%20Shop%20DC%20location.png.html)

[Robert Payne]

Peter,

I would recommend using the shortest intake ductwork possible with minimal turns (I use 6" S&D PVC with my ClearVue cyclone) and larger diameter exhaust duct to your planned exit port. Remember that you will lose conditioned air using an external exhaust, so be aware of that factor. I use 10" HVAC insulated flex (the type used in many homes for feeds to air vents from heat runs) for the exhaust side with minimal turns to reduce back pressure drag and only exhaust outside during the summer months. I use return filtered air to the shop during colder months.

[Dan Friedrichs]

I said this in another recent thread on this topic, but just to repeat - consider going without the cyclone, if you're venting outside. A Thien separator (or something similar) will get all the big chunks, and may add less pressure loss to your system than a cyclone. Plus, a cyclone is physically large, and expensive (if you haven't yet bought it). I vent outside with just a separator, and it works great.

That said, my SWAG at your original question is that it doesn't really matter. Frictional losses against smooth PVC are minimal at these velocities. Robert makes a great point about the larger diameter exhaust, too.

[Robert Engel]

I think its logical and will work.
My thinking is you're not going to affect the performance much with a piped exhaust, especially if you keep the diameter big, like 8".