chappcc wrote:Depending on how well you have insulated the group, the thermosyphon could stall. The flow rate through the thermosyphon should be directly related to the rate of heat loss through the group. The temperature stability of the group is derived from its mass, so insulation shouldn't really affect temperature stability.

It can and will stall, I'm counting on it. Between any 2 pulls I notice at least a 5F decrease in temp, sometimes a bit more, in the time it takes me to grind and prep the pf for another pull. This is with no cleaning flush at all. Bad habit, I know. I do cleaning flushes normally after the session is done, perhaps half a dozen singles and the odd double now and then. If I walk away and leave the machine on, it will recover from the stall on its own and I notice very high temps in the group which renders it too hot to use (with the insulation it has)unless I cool it first, so I like the little mini stalls between shots... it resets my start point and lets me choose it very precisely with little mini flushes, I'm talking a sip here and sip there with water barely coming out the shower screen and watching the temp climb a couple degrees each time. Wasteful of water, in the normal 6 singles morning routine, I use up perhaps half a ricebowl of water which gets thrown out, and this includes heating up the machine from dead cold. Acceptable, for me. The Strega has slightly less waste water, but its a new machine and I do cleaning flushes after each shot on that one, paranoid about it getting dirt in it.
JB, with the double dip pull this morning (my first time), I definitely had more crema. Tastes... seem better, there was a tinge of a liquor taste in the back which I can sometimes get but it was there more often today, there were definitely more flavors but I haven't decided if I like all of them yet...