Temperature surfing an HX espresso machine? - Page 2

#11: Post by **CRCasey** » December 5th, 2009, 10:52 pm

Strangely I find the same type of audio cues in steaming milk. Milk will talk to you and tell you when it is done steaming by sound more than it will by a thermometer.

-C

December 5th, 2009, 11:18 pm

HB wrote:I assume Paul refers to how the water calms down during the flush.

That was my understanding as well.

Koffee Kosmo wrote:View the water cascade and when it runs like an ideal coffee pour turn off
It will be spot on temperature

Apologies if I've misinterpreted your post. I'm assuming "coffee pour" refers to an espresso pour. If so - no, the end of the water dance does not look the slightest bit like an espresso pour to me. And the temperature comment sounds like a flush & go recommendation, which is not optimal for all machines.

December 6th, 2009, 12:29 am

No problem RC
I do understand and agree on what you are saying in that it may not be optimal for all machines
Many other factors also come into play over and above the machine design

But its a good way to learn about cooling flushes and the method has a repeatability factor
I have also observed that in summer a cooling flush runs longer in time than in winter

It may just be that it works on my machine
KK

#14: Post by HB » December 6th, 2009, 1:34 pm

Koffee Kosmo wrote:It may just be that it works on my machine

No doubt. I expounded on this point here and excerpt it below:

HB wrote:Having written a number of reviews, I've come to recognize differing degrees of how heat exchanger-centric a particular espresso machine is. My shorthand for these distinctions are:

Dragon - key characteristics are lots of flash boiling, fast recovery, nearly zero thermal memory, and slowly rising brew temperature profile. Simply stated, after the cooling flush, the heat exchanger output is the brew temperature. Examples include the Elektra Semiautomatica, Gaggia Achille, and the Olympia Maximatic.

Mixer - key characteristics are modest flush, medium to slow recovery, considerable thermal memory, and initial rising then falling brew profile. Unlike the Dragon, the Mixer's brew temperature isn't determined solely by the output of the heat exchanger. Other factors, such as cool water mixing via an heat exchanger injector, backflow from a thermosyphon, and the attenuating effect of a heavy grouphead temper the final brew temperature. Examples include HX E61 espresso machines like the Vibiemme Domobar Super and Quickmill Vetrano.

Agnostic - key characteristics are small, fixed volume flush or none at all, and long thermal memory. Careful tuning of a Mixer with tweaks in the design can produce an espresso machine that is heat exchanger in name only. Examples include the Cimbali Junior and Nuova Simonelli Aurelia.
As the last entry suggests, these categories are not immutable. With minor modifications or boiler pressure adjustments coupled with barista techniques, an espresso machine that naturally fits in one category can morph into one of the other categories (e.g, Ian's HX Heaven or 1½ Boiler).

I need to integrate these points into the HX Love article.

Back to your comment, Jim will be posting a review of the Bezzera BZ07. He reports that it's a "Dragon" type HX that responds well to the flush-n-go technique you describe. Some HX espresso machines (e.g., Quickmill Anita/Vetrano) fare much better with the flush/rebound technique described in HX Love; others are somewhere in between (e.g., Vibiemme Domobar Super).