I have a 3 ring burner, a 20 jet Mongolian and a NASA
My BIAB..........
I started with the 3 ring and BBQ reg on my original 25L batches. Slow but it got there.
I started modifying it, drilled out jets and outlets it helped heaps.
Then I put a 0-207kPa reg on it, it made a huge difference
It ran my single system no problems.
When I got a 50L batch I went for the 20jet Mong.
Got sick of waiting for it to get the water to strike temps, so added a 0-207kPa reg. Helped heaps.
The downside of the Mong is I find it soots up the pot, yuk black shit...
When I started the 100L batches (remember this is batch not boil size, boil size is a lot more) the Mong cried. I used to have to run it so hard the centre jets used to glow red.
I then moved to 2 x NASA burners under the 100L batch and it rocks. One NASA would be enough, but 2 saves times.
With my 3V............
I've only been doing 69L batches, in the big pot from above as the kettle. I have also started brewing in the carport, so wind is reduced a lot (although I do live close to the beach and always brew with the roller door up) These days I only ever run 1 NASA burner under the pot.
IMHO NASA burners (aka Turkey burners) rock. Their downside is they can be noisy, which may not be good if you live in units. It is a great burner to do a single batch, and give the flexibility to update to larger batches later. Don't even think of a 3 ring trying to do a double.
(the Mong with the 0-207kPa reg is also noisy) I've found not a great deal difference in LPG usage between the burners per batch.
Also something to take into account is if you are going to use it for BIAB or 3V
With BIAB you tend to have a full volume strike, so you need to heat all the water to the strike temp up front. Then when you go from mash out to boil you have the full vol.
With 3V you bring approx half the water up to strike, then dump it in the mash tun and then heat the mashout water. In my case this is in the HLT which is elec. So the LPG burners only need to get the wort from the mash temp to the boil (about 30c difference), so it doesn't matter as much if it takes a bit longer. Also I tend to fire up the burner under the kettle while I am sparging, so the kettle is often waiting on me.
Also I'm impatient with the burners on brew day. If more heat can save me time, then I want more heat. You may not mind waiting an extra 15-30mins for it to get to temp.
QldKev