On Apr 16, 4:54*pm, BobR wrote:
On Apr 16, 10:20*am, (texan1) wrote:

Seems like we need to replace a roof after most recent storm in our
(Dallas,TX) area.I'm thinking about putting impact resisting shingles and
since it requires
more ventilation I can't decide if I should put additional wind turbines
or have a solar fan installed instead. Our electric bill is not that high
during the summer so I'm not sure if there is any benefit of having a
solar vent + we have plenty of wind to keep turbines rolling.

Any advice will be appreciated.

Since I live in the Dallas area as well, I have to comment on your
statement about having plenty of wind. *YES, we have plenty of wind
right NOW but not necessarily during the hottest part of the summer.
The wind turbines will however work even in light or no wind
conditions if you have good soffit venting as well. *The heat on the
roof will help to create a constant movement of air from the soffits
to the peak of the roof. *The wind turbines will allow that hot air to
escape while pulling in air from the soffits. *

I don't see that you get any mechanical advantage out of this scheme.
If there is enough wind blowing, I can see how a turbine vent can use
the wind power moving by the roof to move air out of the attic. It's
using the force of the wind as power. But I don't see how naturally
rising hot air moving from the soffit vents and up through the turbine
is doing any good beyond what just a plain similar size vent opening
would give. In fact, it would seem to be worse, because there is
some energy loss in friction, etc with the turbine.

In other words, in still air, I think you'd be better off with just a
ridge vent.



A solar powered fan
will produce a more active vent but only when the sun shines.

I used to have an electric powered vent that came on when the
temperature reached a certain point and would cut off when it cooled.
The problem with them was always NOISE! *They were very noisy and so
the last time I had the roof replaced, I opted of the ridge vent
system instead. *It works on the same principle as the turbine vents
and allows the hot air to excape while pulling cooler air from the
soffits. *If you are replacing the roof anyway, that would be the way
I would go.