HB wrote:At some point, yes.

Great, the results should be very interesting!

timo888 wrote:If the brew temperature can be lowered by a longer preinfusion, or kept higher by a shorter one, it would be possible to pull a shot at a lower or higher temperature...

That would be pretty cool... sort of like controlling the flush time on an HX. Of course, a longer preinfusion would change more then just the temperature...

Reminds me of a quote I just read on another forum- "An art is a science with too many variables." - P.N. Adams

Regards, Henry

Yes, the boiler pressure is around 1.0 bar. The factory setting was 1.5 bar, which is probably in line with the brew temperatures you want. It was too hot for the coffees I use. Another possibility is to flush the group to raise the grouphead temperature for an on-the-fly adjustment. I haven't measured, but my guess is that a hard 3 second flush just prior to the pull would do it. For my usage, a very short half flush and then a minute delay for stabilization works best if the machine was idle; otherwise it's no more than a spritz to knock off the grounds, then lock, load, and pull without a delay.

timo888 wrote:At 1.1 bar or higher, if the thermosyphon is flushed once when the false pressure has been dealt with during initial heatup, the Lusso will idle at-temp, not cool.

As noted in the video credits, the boiler pressure was 1.1 bar for these measurements. BTW, how did you measure the brew temperature? Not that it makes a lot of sense to speak of "idles at temperature" when the brew profile is shaped like an inverted U.

timo888 wrote:If you do not purge the thermosyphon with a brief flush (an ounce will suffice) after the false pressure has been bled at startup, the Lusso's group will remain near room temperature even after a couple of hours.

I've never observed the Lusso's group remaining at near room temperature without an initial brief flush. I don't recall any of the other Smackdown participants mentioning it either. Maybe it is unique to your machine? We heard a few similar reports of thermosyphon stalls among Vibiemme owners. I don't doubt the reports, but I was never able to reproduce the problem.

When you say the Lusso "idles cold", are you speaking literally, i.e. referring to the room-temperature group and the need for a thermosyphon purge?

What I meant by "idles cold" is that the grouphead temperature drops to ~150F measured with a thermofilter (as shown in the video). Other machines I've measured in a similar manner idle around 185 to 195F. I haven't read the patent yet, but I assume the Lusso's cold nose design intentionally counterbalances the over-temperature steam boiler water during an extraction. After a long idle period, I find the Lusso performs best if it's given a short flush and then allowed to stabilize for a minute or so.

I measured that with my tongue: walked up to the machine after a few hours and directly pulled a tasty espresso with no warming flush.

Sorry, that doesn't match my experience. I used the Lusso for months without temperature measurements and the taste of the first shot exhibited classic signs of low brew temperature (sour taste, lighter crema color). This was later confirmed using a custom thermofilter. It takes very little effort to get the Lusso ready for brewing, but its walk up and pull brew temperature is too low for the blends I use.