Thanks for the inof on the Esbit. I haven't been able to bring two cups to a boil in every attempt I have made. I have tried:

1 esbit tab with tin foil to focus heat - it got the water hot but not to a boil. Then I added some wood kindling. Total burn time was about 15-20 minutes. No boil.

1 esbit tab plus several pieces of fatwood - hot but no boil.

1 esbit tab plus fatwood plus a bunch of kindling sized wood - hot but no boil.

Elevation was about 300 feet above sea level.

When you used 2-3 esbit tabs and got a boil, was it in succession or together? And was it one cup or two?