1. "Turbine ventilator" is used by one company.  You may particularly 
like the name of one of their products - Superwhirly
http://www.edmonds.com.au/html/products/superwhirly_turbine_ventilator_300mm.htm

2. Even without wind, hot air can still rise up the pipe (the principal 
  I think you put forward in your first message connecting them to a 
stovepipe vents) and with enough movement may even get the thing 
spinning which could then feed itself but the fact that after initial 
cost the thing works for free is its main strength, I think.

Tim Carter at Ask the Builder likes them.  See this for his explanation:
http://www.askthebuilder.com/442_Roof_Turbine_Vents.shtml

T. Gale (not a wind expert despite the name)

[log in to unmask] wrote:

> 1.    What do they call those, anyway?   Merry-Go-Rounds?
> 2.    OK, so when the wind blows and spins the thing, it exhausts the 
> vent.  That doesn't seem very ... reliable.   Like, "put your milk on 
> the window sill and it will remain chilled - unless it's July".      
> Except for sails, weathervanes, Kansas farm pumps and Christo, do people 
> design things to perform their function only if the wind is blowing? 
>  
> Christopher
> -- To terminate puerile preservation prattling among pals and the 
> uncoffee-ed, or to change your settings, go to: 
> http://listserv.icors.org/archives/bullamanka-pinheads.html

--
To terminate puerile preservation prattling among pals and the
uncoffee-ed, or to change your settings, go to:
<http://listserv.icors.org/archives/bullamanka-pinheads.html>