malachi wrote:what i was pointing out was actually that the espresso machine is a means to an end - not an end in and of itself.

Yeah, that's what I meant, just came out in a lot more words. God I love being an engineer

Michal wrote:This is starting to become a boiler/science battle and not a "Double boiler espresso machine recommendation" so maybe I should start a new thread If anyone would like to split it off that's cool too.

Happens a lot - and usually leads to productive discussion. Nothing to worry about - Dan will split if need be.

malachi wrote:what i was pointing out was actually that the espresso machine is a means to an end - not an end in and of itself.

Wow...That's deep. But I must say I TOTALLY agree. I'm sure I'll be limiting my espresso WAY more the thickness of the boiler ever will.

malachi wrote:what i was pointing out was actually that the espresso machine is a means to an end - not an end in and of itself.

The difference between the artist and the engineer. It's not that we can't see the cup is end, we're just wired to love the details of how you get there. Put me down in the "Engineer" / "How does it work category?". Haven't got an artistic bone in my body.

As there isn't a wealth of information on the Brewtus III yet I thought this would be helpful to people considering the Brewtus, http://www.wholelattelove.com/art...light_brewtus3.cfm

karl_a_hall wrote:Specific Heat (concerning boiler thickness, this is actually a large factor in heat transfer equations, hence why boiler thickness has a lot to do with stability... thicker boiler = more stability = less ability to change temperature quickly... read especially the section on Heat Capacity)...

Valid concept (heat capacity), but in my opinion being inappropriately applied here. Given: if I have 2 pieces of the same metal and one is thicker then the thicker/heavier one will require more energy input to change temperature.

But, IMO, it is most likely that the primary factor for (uninsulated) boiler temp stability is that the heat capacity of the mass of WATER being contained is MUCH greater than the heat capacity of the thin metal shell container (just check the linked wiki page table to compare Cp in kJ /(kg*K) for liquid water vs. copper). So if your identical two example (copper) cylinders each contain 1.5 liter of boiling water and one cylinder is 1/8" thick and the other is 3/16" thick what real-time difference in rate of cooling should we expect to see? In terms of making real-time temperature adjustments for espresso brewing, I would think that small differences in the boiler metal thickness should be a non-factor.

As my good friend RapidCoffee asserted, thicker boiler metal has the advantage for being mechanically stronger but most likely has no real affect on espresso brewing or ability to adjust brewing temperature. And in my experience, boilers tend to fail at fittings and welded seams (almost never through the body metal) so any perceived strength advantage for thicker metal might be debatable as long as the structure is satisfactorily rated for the stresses.