Why are these fitted instead of just a stationary vent like you see on caravans?
I don't see the point in using the wind to power a vent, when the air was already moving. Surely that's like fitting a generator to your bicycle to power a motor to make you go faster?
They are just more efficient than a simple hole in the roof with sufficient cover to keep the rain out. If there was a better mouse trap, somebody would have made one in the last 200 years.
As it spins I think it disperses driver/passenger farts far more efficiently.
Yes I know they claim to be more efficient, but why? How can you take power from the wind to then give it back to make it faster? Isn't that breaking the laws of physics?
Is there a special catalyst inside it for that?
They are powered by the wind that is blowing, not wind they are making.
In the case of the van, they are powered by the wind pressure the van creates when moving.
Gym Sulkinson Fork wrote
They act like a pump.
It isnt from the place you want to move it from.
Nope, more like using a wind generator to generate electricity and using the electricity to drive a fan, but without the losses involved with the electricity generation and the electrical fan.
Because they are a fan, powered by the wind.
That isnt how they work. Think of it as a fan, which even you should realise is better than no fan, and powering that fan with the wind.
Nope.
Like? I wasn't doing anything else at the time, I was waiting for someone to answer their door.
Why not just channel the blowing wind where you want it instead of converting energy twice?
The above link claims it works when stationary too (by wind).
But the point is to move air into or out of (shouldn't matter which, air still goes through the van) where the vent is. Why not just let the wind blow the air into the van? Making that wind turn a vent which then sucks air in is utterly pointless.
A turbine converts wind to electricity. A fan converts electricity to wind. What we have here is something that converts it and then straight back, pointless. You might aswell put a wind turbine and an electric fan connected together on there, it would be no more stupid.
But you're powering that "fan" by the motion of the air, then using the power to create motion of air, which was already there anyway. It would be like having a solar powered lightbulb.
Because those things are extracting air from the house or van so that isnt possible.
Yes it does. You've likely noticed that houses don't actually move very fast and do have those vents too.
It does actually, particularly when getting it to remove the hot air in the roof space in summer.
Doesn't work when the van is stationary.
Wrong. That's the way the hot air in the roof space wants to go, out of the roof space, and so its better to help it go where it wants to go, with a fan and have the fan powered by the wind.
Yes, with houses, an electric fan is better, but the big advantage with those wind powered fans is that its driven by the wind.
I suspect you are just trolling, but I'll chime in anyway. These devices use the motion of the air traveling past your building (ie, horizontal motion) into suction that draws hot air up and out of your building. They work better than just using the upward motion of the air created by hot air being lighter than cooler air.
Why is it better to move it out instead of in? It still has to go in somewhere and out somewhere else. Same ventilation takes place overall.
I've occasionally seen them on old houses on chimneys. I thought that was to disperse the smoke.
but if you let the wind blow it in, then it goes out where it's currently coming in.
The same wind that currently spins the vent could do so.
I'm not.
I find it hard to believe it really matters whether the air goes in our out.
I'd just open the window (with a rain guard of course).
Yes, but that still does help move the hot air out of the roof space.
What you actually have is a more efficient way of using the wind to power the fan, without the inefficiency involved in the use of electricity between the generator and the fan.
Yes, that would certainly work too.
Much more stupid given how inefficient the wind powered generator is. Much better to have the wind turn the vent and have the fan part of that thing that turns, directly coupled.
Yes.
Nope, not with the hot air in the roofspace.
Nope, those are much less efficient and we do have solar powered light bulbs, with batterys in them so you get the light at night after the sun is gone.
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