When they installed our turbine in the garage roof there was a
DISTINCT upward movement of air when the hole was cut and wood
removed. Hot air rises by convection and my understanding is THIS is
the driving function behind the rotation of the turbine. Ours rotates
without exterior breeze.

On Fri, 03 Dec 2004 12:37:42 -0600, John Willis
wrote:

On Fri, 03 Dec 2004 16:07:13 GMT, "bill a"
scribbled this interesting note:

"Zypher" wrote in message
thlink.net...
I've always wondered if those 'turbine ventilators' really work? Do they
really move that much more from the attic space than say a dormer might?


In the past, I've read that they are mostly a gimmick.
I think that a similar "stovepipe" type of structure with
a weather cap would do just as well. Some vertical
height would seemingly let it draw like a flue, as
opposed to the low profile static vents they sell at HD.
I haven't seen any recent tech info on this, though.
Bill


http://www.naturalhandyman.com/iip/i...fattfan3b.shtm

is one place with some information about this. Here is an excerpt from
another site:
http://www.homeimprover.com/articles...entilation.htm
"Turbine ventilators are wind-driven devices which are designed in
such a manner that wind from any direction causes the upper portion of
the ventilator to rotate. As the turbine rotates, or spins, a reduced
air pressure in the stack draws hot or humid air from the attic
space."
This last piece seems to explain it better than most any other source.