No it doesn’t. (He says, looking up from the lecture about work and energy he just happens to be writing to give later today…)

-cvj

As far as the squeaks go. They make them now with sealed bearings.
Check out the SupaVent. It is the best made. And I’m not just saying so because I sell them.

[advertising snipped out by cvj]

It squeals like helll!
I have used WD-40 on it in the past and it worked for a few months but now here we go again.

I’m gonna look for that graphite lubricate thingy…
I’m wondering if w15 car oil will work as I have some to spare.

Best,

-cvj

Re “Where’s the flaw in my reasoning?”. The wind makes the turbine turn because the turbine is not balanced. That is, one side catches the air, the other does not. So it is caused to rotate. To see this, consider what happens if you don’t let the unit rotate. Looking at it, you can see that the wind will catch it on the left more than on the right (small rotations cause a larger change in volume contained on the right than on the left), and so it will spin with the left side going away from you. (I.e. clockwise as seen from above.)

Upon rotation, the turbine effect causes air to be sucked out of your attic. This effect shouldn’t need explaining in that it is clear that if, in the absence of wind, you spun the turbine it would act as a centrifugal turbine and would expel air.

Then the problem with it only working in this enhanced mode when there’s a wind is that it is precisely when there is little or no wind that you need the greatest effect. But perhaps a little goes a long way, which would be nice. Less energy use on cooling the house in the Summer.

Cheers,

-cvj

Cheers,

-cvj

Here’s a test. Wait until it’s a 5 to 10mph day. Crawl into your attic. Measure the air speed up the vent by using a piece of tissue paper to see how fast the air moves. Now jam a stick in your air turbine and repeat.

I bet that you will find that the thing does assist in ventilation.

As far as stopping one from squeaking, clearly if it stops squeaking when you oil it you have found the problem, the issue is that the oil doesn’t last. To make the oil last longer, either use a thicker oil (like one that’s designed for this use), or better, go with a non oily graphite lubrication that won’t attract dust or dry out.

My mother has some of these vents on the roof of her home and they can really squeal on a windy day. We’ve tried lubricating them, but it doesn’t seem to last. I should mention that they are at least fifteen years old.

Let me put it another way. It would be like claiming that if I start with two light aircraft sitting on the runway, one with propellers and one without (but otherwise identical), the one with propellers is better able to spontaneously start barreling down the runway and take off. I find that hard to believe. It takes work to turn the blades.

Cheers,

-cvj

-cvj