That really is the main consideration. A 30" fan requires TEN square feet
of exhaust to function to maximum. When you get to figgering vent space,
that's quite a bit. And if the fan gets bigger, then the exhaust area
multiplies accordingly.

s



wrote in message
...
On 30 Jan 2008 09:23:02 -0800, Banty wrote:

But I was told that it's not good to use with ridge vents and soffit
vents.

I doubt they really allow enough air flow