On Apr 9, 4:19 pm, "vwaldoguy" wrote:
Hello,

I've got a 3 1/2 year old home with three 14" vent turbines on top.

snip

Just get rid of them. There are static fixed vents that are far less
ugly and more efficient besides. Virtually all of these installations
are 'feel good' devices so that the owner can see something happening
that resembles ventilation. About on a par with the ribbons that cheap
motels used to tie to the air conditioning units to keep the
sweltering public from complaining. Anyone with a rudimentary
knowledge of physics can see the faulty logic in these dvices. HTH

Joe