Ideal distance from burner to the bottom of keggle ???

[beeronious]

I just finished building the 3 tier gravity feed stand and now all I have left to install is the burner.
I'm using a cast iron one with output of 18186 BTU.
I plan on making it detachable from the stand and move it from one tier to another how needed, since now I cannot afford getting two more

I'm using three 50 litter keggles so what would be the optimal distance from the bottom to mount the burners ?

Here are some photos o the burner, stand and the keggles:
http://postimg.org/image/paduswqvl/
http://postimg.org/image/76au89t75/
http://postimg.org/image/bqx0n7cwh/
http://postimg.org/image/z3v25pt01/

Beerly yours,
Beeronious

 

[flars]

I think the hottest point of a gas flame is just beyond the white to light blue tip of the flame.