Thanks for the response and your pictures.

Well I can put more holes on one side of the wind screen to allow for more air. However I think reduced air would just put the fire out not make it less efficient? The pot height from flame and pot material may be impeding the heat transfer/boiling, but at the end it's just not burning as long as the site says.

One thing I do notice is the simmer ring doesn't burn like in the picture: http://www.csun.edu/~mjurey/jpgs/simmerburn.jpg
It's just a huge flame coming from the center (not 6 distinct smaller flames. Perhaps too much vapor is coming out? Maybe if I can seal around the can somehow...

P.S. Where did you get such thick coat hangers? I've been trying to find some sort of aluminum rods, but so far no luck.