I really need someone to enlighten me about hoods.

B/c of the "architecture" of my kitchen, I cannot get a "ready" commercial hood (unless installer #5 will tell me otherwise).

I was told to get a motor and install two in-line vents, connected in something like an inverted "Y" fashion (I forgot the technical term for it). But they will be 6 ft above the cooking surface. Also, they told me I could only get total 450-600 cfm from both vents combined, which is clearly not enough for a vent that is so high above the cooktop.

The problem is that the opening for the vent we have now, is not centered in relation to the cooktop b/c of a joist in the ceiling. Also, there is a brick cove around the cooking area and I cannot do much about moving the cooktop. The distance from the front wall to the back wall of the cove is ~15" and the distance from the center of the vent opening to the left wall is about ~8", so attempts to find a commercial hood have proven hopeless - so far.

Now, I have read here that external blowers are quieter than internal ones.

That brings my question. Would it be possible to use an external blower with a cylinder "tube" hood, similar to Faber Cylindra hoods? Does anyone sell "small-footprint" hoods w/o a motor? What kind of filer do I need?

TIA!

Here is a link that might be useful: Faber hood