In reply to wilkesley:
> I set the stove going, so that the flames didn't come up beyond the base of the pot.
As with all stoves, it is probably a good idea to measure the amount of fuel used. Then you can objectively measure the fuel efficiency (comparing the mass of fuel to boil a given volume of water from a starting temperature to the energy required to do that in a perfect environment). A heat exchanger system
ought to be more fuel efficient. If it isn't, then something is probably wrong somewhere.
[edit] the 10g MSR PR vs 18g Brukit fuel use reported at STW doesn't sound promising... Anyone fancy repeating the test? [/edit]
Boil times are one measure only, and, generally, a pretty poor measure unless you're someone who really needs a quick brew (squaddies, perhaps).
The main reason that boil times feature so widely in reviews is because it's an easy thing to measure objectively; what the burner up to '11', and measure the time to boil. If you're a good reviewer, you'll start with water at the same temperature, and a fresh canister of gas for each burn.
Heat exchanger systems are essentially intended to allow the burner to run closer to '11', by increasing the effective surface area used to pull heat from flame & hot gas. Thus giving faster boil times in those all-important reviews...
Stove design is a compromise between fuel efficiency, pan size, weight, system volume, etc. And everyone has different views on which of those factors makes the 'ideal' stove.
A stove that is very fuel efficient may not be the lightest
system, since the extra weight of the HX and other sundry bits make it heavier. And you could be carrying more fuel for a lighter cooking system, and still end up carrying less weight. I surprised myself with an analysis of this situation a few years ago:
http://www.outdoorsmagic.com/forum/gear/comparing-meths-and-gas-weights/373...
Of course, that's only important if weight is your primary concern.
Post edited at 18:58