Hey all,
 I discovered rocket stoves only yesterday, so I naturally stayed up till 2 in the morning watching videos. I found this [youtube]Rocket Stove Hot Tub pt.3 test firing: 
http://youtu.be/wHeegB1PMfA[/youtube] video intriguing - it's a rocket stove heated hot tub.
 There's actually a series of 4 videos (I recommend them all), but what I wanted to ask you guys about was his design. I'm still learning (obviously), but a few things struck me as odd.
 
There entirely no insulation around the main chamber.the water pipe run right down the main chamber, which i understand would impact the burn efficiency
 Overall, I thought it was awesome, and I was really impressed with the guys creativity and craftsmanship, but wanted to get some expert opinions on his design.
 Cheers all!