I maybe an idiot but as an experiment can you turn the upright holding boiler 180 degrees on base . Weight base down then try it ?
Why ? You ask .to lower the burners down a bit as i feel the wicks are to close to the boiler .
Apart from it works ok for what you need
Cheers
Dennis
I think Dennis is right, playing with my stirling engines I have found the tip of the flame to be Much hotter. You may also be able to just put a roughly 1/2 inch or so spacer and longer screw under boiler mount and leave the boiler in the stock configuration but taller. With the height at a better level you may easily find you get longer steam runs on a single optimized burner(like Jan suggest)....just a thought.
Would you mind sharing what the china boiler cost or a link? I have not seen these listed before.