I think I started a thread quite some time back on this subject. Anyway, I found some cheap Tiawan cast skillets to make the burner assembly out of at the show last weekend. Been doing some preliminary work and now have the burner about ready for the 40 gallon water heater tank. Got lots more to do. I am using these folks ideas. It's an old Mother Earth design they have updated.
Here's what I have for the burner.
First up is the lower 8" skillet. I drilled these parts clamped together so I know the holes will line up. I have a plate attached to the bottom for mounting inside the tank.
They say to space the plate 3.25" up so I cut some 3/4" pipe spacers.
1.5" spacers for the top 6" skillet.
And the top skillet.
And you can see these are cheap skillets.
More to come as I progress! If you read the article in the link above, one guy is getting 1000° out of his. Don't think I need that much!