Lawrence Brewers Guild

Does anyone have experience with a flat coil immersion wort chiller? the idea being a flat coil of copper that is suspended just below the top of the wort, and as the wort cools it creates a natural convection cycle. mentioned here as a Planispiral Wort Chiller.
http://www.brewingtechniques.com/librar ... hcomm.html

Never heard of it before now. Found the below post which includes pictures of one. It seems that the tubing isn't actually flat, just small diameter 1/4" OD or so, and tightly coiled. Seems like it could be a pretty cheap experiment to undertake due to the small amount of copper required.

http://jimsbeerkit.com/forum/viewtopic. ... &sk=t&sd=a