I stand corrected. I wasn't aware of these fans (a little more pricy than
what I'm used to seeing in my inspection in the plan's materials.) They do
advertise that they include an infinite speed control for the fan, which
would appear to be exactly what you were looking for. Definitely not your
everyday range hood (as the price would indicate).

That isn't true. There are "infinitely variable" inline fans for range
hood exhaust. Maybe some range hoods come with an "infinite variable" fan
in the hood (you turn a dial to turn the fan down allthe way to 0).
Fantech's fans can be speed controlled to 0.
Exhausto's fan is nice in that it has a door that you can open to clean
it, so it can be cleaned at home with soap and water, they say. I don't
think Fantech's fans are openable. Apparently either BESF or RSIF from
Exhausto is good for inline range hood exhaust.

Laura