There does not seem to be good information out there for burner BTU in correlation with burner model and time to reach boiling etc. It would be interesting to see some data to help close this situation out rather than using BTU formulas and guestimating at 50% efficencies.
If you would like to participate: Please reply with the following-
Burner brand and model
Regulator PSI (I know, BTU is BTU, but not likely if you changed your regulator).
Brew Kettle Type and Size (aluminum or steel, thickness of kettle bottom would be a bonus)
Gallons of Water at Start
Temperature of Water at start of flame
Air Temperature (indicating if windy would be a bonus)
Time to reach boil (noting your boil temp based on elevation would be a bonus).
Please cover your kettle with a lid so we have comparable data.
Hope to get some participants.