On Thu, 25 Oct 2018 18:07:44 +0100, Ed Pawlowski wrote:

On 10/25/2018 12:15 PM, Gym Sulkinson Fork wrote:
On Thu, 25 Oct 2018 17:10:21 +0100, Pat wrote:

On Thu, 25 Oct 2018 16:58:21 +0100, "Gym Sulkinson Fork"
wrote:

On Thu, 25 Oct 2018 16:31:38 +0100, Rod Speed
wrote:



"Gym Sulkinson Fork" wrote in message
news On Thu, 25 Oct 2018 16:03:22 +0100, wrote:

On Thu, 25 Oct 2018 15:47:48 +0100, "Gym Sulkinson Fork"
wrote:

Why are these fitted instead of just a stationary vent like you
see on
caravans?

http://www.flettner.co.uk/van-roof-vents/

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.

Yes I know they claim to be more efficient, but why?

Because they are a fan, powered by the wind.

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.

How can you take power from the wind to then give it back to make it
faster?

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.

Isn't that breaking the laws of physics?

Nope.

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.

I suspect you are just trolling,

I'm not.

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.

I find it hard to believe it really matters whether the air goes in our
out.
If not trolling, just a hardhead that refuses to accept a better idea
that works. Have you tried one?

No, I was just asking how it works.... It would appear Mr Speed has provided a satisfactory answer.