HX brew temperature control via mixing?

#1: Post by **pocojoe** » March 24th, 2012, 2:49 pm

For those of you who know the commercial designs inside-out: do any HX machines regulate brew temperature downward by adding in lower temperature water at the brew head?
Tnx
Joe

#2: Post by **jmc** » March 24th, 2012, 4:41 pm

I don't pretend to know every machine, or even most, but I doubt it very much.
Every commercial machine has so much brass in the group head that changing temperature would take too long.
They are also fairly finely balanced systems which allow the barista some leeway in temperature control so why would it be necessary or desirable ?

John

#3: Post by **another_jim** » March 24th, 2012, 4:57 pm

pocojoe wrote:For those of you who know the commercial designs inside-out: do any HX machines regulate brew temperature downward by adding in lower temperature water at the brew head?
Tnx
Joe

The jetting and valving of some thermosyphons allows a small amount of cold water to be pushed from the pump to the group, tempering the overheated water from the HX. The Aurelia does this (I'm told), as do the well built E61 machines (but alas not the home cooked versions.)

#4: Post by HB » March 24th, 2012, 5:13 pm

That's what the Rancilio XCelsius announced at last year's SCAA conference says it does:

Rancilio wrote:Xcelsius is the newest patented temperature control technology from the Rancilio LAB. The key features of the system are the unique water system with double-phase heating, the architecture of the brew group and innovative control electronics... With Xcelsius you can easily adjust and guarantee the stability and the precision of the coffee brewing temperature in any situation. Xcelsius features elements that are profoundly innovative and different: in fact, Xcelsius has been developed to be flexible and dynamic. This is something completely new and means that is it possible to extract coffee and dynamically change the temperature of the water DURING the extraction process, which is known as TEMPERATURE PROFILING.

I got a quick demo of it while I was there and asked questions. From Going to SCAA 2011: What would you like hear more about?

HB wrote:Paul Jones and I also did a quick side-by-side comparison with Metropolis Redline using flat and declining profiles. The results were far, far from conclusive, but the shots were good, which is impressive in itself from a manufacturer showroom booth. As I understood it, it would be generous to describe it as "completely customizable" temperature profile. More like a generally flat, declining, or rising profile, at least based on the description their sales and later engineer provided (it may be oversimplification, but it sounded like a mixing chamber of heat exchanger and incoming cooler water to provide the desired profile). Mark Prince of CoffeeGeek recently published an article on his Rancilio visit and he mentioned the xCelsius; he says he'll publish a follow-up article. I asked if this design would be trickling down the consumer models; the Rancilio representative was non-committal, pointing out that the commercial side of the business was driving all their R&D efforts.

March 24th, 2012, 10:02 pm

Thanks.
Seems like a good idea, but there is a long path from concept to coffee.
Joe

#6: Post by **Dogshot** » March 24th, 2012, 10:59 pm

La Cimbali does this with what they call "thermodrive". They currently have it on some of their commercial machines, but unfortunately not on their Junior.

http://www.cimbali.com/eng/news_dettagl ... id_news=41

Mark

March 25th, 2012, 12:08 am

I like their little picture- yes, that is what I had in mind.

Thanks
Joe