Ponte Vecchio Lusso brew temperature tests - Page 2

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hbuchtel
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#11: Post by hbuchtel »

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
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timo888
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#12: Post by timo888 »

Or a science where the same question can have more than one right answer :)

But since it's a passive preinfusion, the preinfusion-induced changes would be less than if the spring (held back by the barista's hand) had been pushing the water through.

Regards
T

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roastaroma
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#13: Post by roastaroma »

HB wrote:For all of these espresso machines discussed in this post, the boiler is under steam pressure of approximately 1.0 bar, thus the water boils around 250 degrees Fahrenheit instead of the usual 212 at sea level.
Just confirming: For that Scace test above, your Lusso's p-stat was set to 1.0 bar, correct?

If I were getting a Lusso (highly likely at the moment), I'd be looking for a brew temp around 205F usually. So 1.1 would be too high for that, would you say?

Grazie, and carry on brewing!
Wayne
"Non è la macchina, è la mano."
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HB (original poster)
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#14: Post by HB (original poster) »

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.
Dan Kehn

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roastaroma
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#15: Post by roastaroma »

Oops, I must've left my brain at home today! :roll: I could not have meant 205F measured at the PF; more likely I was thinking of the boiler temp instead! Thanks anyway, Dan; I eagerly await more Lusso news.
"Non è la macchina, è la mano."
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timo888
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#16: Post by timo888 »

Dan,
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. I'll call that one-time-only flush the 'thermosyphon purge' to distinguish it from a heating flush. Without that purge, the group will remain cool to the touch no matter how long it stays on. If you don't do a heating flush, the brew temp should drop several degrees below the 204-206 you're seeing with a flush.

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T

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HB (original poster)
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#17: Post by HB (original poster) »

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.
Dan Kehn

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timo888
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#18: Post by timo888 »

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. Cold to the touch ... I measured that with my hand, which is accurate enough at room-temperature. But if you do purge the thermosyphon during the start-up routine, within a few minutes the group will attain brew temperature range and remain there indefinitely because the thermosyphon flow keeps it there. 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.

So there is an ambiguity. 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? Or are you speaking figuratively, i.e. "cold" = the group will be a few degrees below optimal yet hot enough to burn your hand? If the former, I agree. If the latter, it's a question of individual taste preference and how the specific roast/blend responds.

Regards
T

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HB (original poster)
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#19: Post by HB (original poster) »

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.
Dan Kehn

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timo888
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#20: Post by timo888 »

Interesting. Ponte Vecchio in their documents claim the machine is always ready to brew, and that was indeed my experience, but only if it had been purged with a flush after the false pressure was bled off -- before the first pull of the day. The differences in our experiences with the machine might be explained by the pressure settings we chose -- yours "around 1.0 bar" and mine between 1.1 and 1.2 (as recommended in the PV manual).

Regards
T