We have two new roof turbines that seldom turn. I noticed that
neighbors on either side of us have turbines that turn even when the
wind is not blowing. I don't believe theirs is powered.
Can someone help me with this problem? Can heat from the attic cause
the turbines to turn or are they only turned by the wind?
Rising air (usually heated) turns the turbines. Any pressure
differential will cause them to turn, maybe even wind could rotate them
at times. Turbines are a passive impediment to air flow, and their sole
purpose is as a 'feel good' device to please their owners by showing
some evidence of air movement. It would be more effective to use
standard roof vents and if you must see whether something is happening
to the air flow attach a few light plastic strips. Fluorescent colors
would be a nice touch.
Maybe your turbines could use some old fashioned lubrication.
I can't find any reputable reference (or any reference at all) that says
roof turbines are of miniscule value.
Turbines do move from 300 to 1300 cubic feet of air per minute out of the
attic (at a wind speed of 5 to 15mph). Assuming 2000 sq ft with an average
attic height of three feet, the 6000 cubic feet of air will be exchanged in
four to twenty minutes. With two turbines, in two to ten minutes, etc. Four
14" turbines in a 15mph wind will change the air in the attic four times in
One test I found showed an 8-foot ridge vent moving from 27 to 214 cu ft of
air per minute, depending on the manufacturer.
Admittedly, measuring apples and oranges: turbines depend on wind speed,
vents depend on temperature differential and length of the vent. But it
seems as if a single, 12" turbine is never less efficient than an eight-foot
ridge vent and can be up to ten times better at moving air.
In other words, in a modest wind, turbines can move an ENORMOUS amount of
air compared to a ridge vent.
The whole controverys seems like an easy thing, though, to test. If your
home has turbines, put a thermometer in the attic. Then garbage-bag the
turbine(s) for thirty minutes and check the thermometer. Is five, ten,
twenty degrees worth it?
Now, as to the OP's original question: Give the turbine(s) a flick with your
finger. They ought to spin like a roulette wheel! If they don't, they need
leveling, lubricating, or replacing. Secondly, there's no rule that says you
can't have BOTH ridge vents AND turbines. On my 3000 sq ft house I have
ridge vents plus four 14" turbines.
And irrespective of which you choose, you can't have too much soffit
Your Physics teacher would give you a big hairy 'F' for a test like
that. Those results can only show air flow vs. no air flow, so of
course the lack of air flow will cause a higher temperature.
A more defensible test would be to remove the whirly things on top of
the turbine tubes and then watch the temperature drop, which it surely
In the case of the stuck turbine, the thermometer in the attic will
show a decline when the whirley thing is removed. Bet on it.
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