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Up at the Sharp End by Alan Frew
Stefano's Espresso Care
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Philosopher
Senior Member


Joined: 13 Feb 2007
Posts: 188
Location: Australia
Expertise: I like coffee

Espresso: Silvia
Grinder: Rocky
Posted Thu Mar 8, 2007, 6:19pm
Subject: Re: Awesome Article, but two points...
 

MarkPrince Said:

but I have to echo the first posters' comments - I disagree with the conclusion that the Silvia is as consistent as a HX machine. I've put several machines head ot head with the Silvia myself, in some pretty intense testing, and where all other things are equal (volume of grinds, tamp, baskets used, etc), it has a hard time matching the shot performance of some of the HX machines that are just as "dialed in" as the Silvia is (ie, temperature surfing, flushing the grouphead, knowing the cycles, etc).

Posted June 2, 2003 link

Alan makes an interesting conjecture attempting to debunk the myth of temp surfing the Sylvia

To quote

"often repeated in online forums that "the Rancilio Silvia is a
difficult and finicky machine make good espresso with." Actually,
I find it easier to make good espresso with a Silvia (given, of
course, a decent grinder) than with any comparable machine.

You read a lot about boiler temperature variations and the need
for PID electronic control, but again, I've never found it
necessary. To prove to myself that I'm not imagining things I
recently conducted a set of three straight runs of 6 double shots
(18 shots in all), measuring the temperature of the shots in the
glass as soon as they were pulled. The coolest shot I got was
67C, the hottest was 69C, and all the shots tasted basically
identical. During the process I simply ignored what the boiler
was doing and just kept on grinding, tamping and brewing. There
are people out there who claim to be able to detect a 1C or less
variation by taste; I'm obviously not one of them."

http://www.coffeeco.com.au/newsletter/september2006.html

Coming from an experienced barista, this seemed surprising until I thought about the premise of temp surfing.

There is a belief that the temperature of the water in the boiler correlates in linear fashion with the measured temperature outside the boiler.  However, Alan certainly notes that the water temperature exiting the portafilter varies vary little regardless of when he makes his pour.

This is not surprising in a machine which contains a lot of thermal mass e.g. heavy duty brewgroup and portafilter.

Thermal mass acts like a thermal 'flywheel' which has a tendency to even out temperature fluctuations.  It buffers marked temperature variations of the surrounding environment despite changing heating inputs.

We are going to build an environmentally-friendly house based on this premise which will keep the house warmer at night during winter and cooler during the day in summer.

Once the Silvia has reached operating temperatures - all components warmed up to a stable level then you should expect much less temperature variations and hence this observation.
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Worldman
Senior Member
Worldman
Joined: 16 Nov 2004
Posts: 1,820
Location: Pittsburgh, PA, USA
Expertise: Professional

Espresso: Expobar Office Control
Grinder: Cimbali 6/S
Posted Wed Aug 8, 2007, 3:52am
Subject: Re: Up at the Sharp End by Alan Frew
 

Alan,

A nice article...thanks.

As far as the Expobar p-stat, mine has one and always did as you can clearly see in the picture. (You can also clearly see that mine has had some modifications, but the addition of a p-stat was NOT one of them.)

Len

Worldman: side insul from front.jpg
(Click for larger image)

 
Len
Len's Espresso Blends
www.lensespressoblends.com
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Luca
Senior Member
Luca
Joined: 27 Jan 2004
Posts: 2,658
Location: Melbourne, Australia

Espresso: H: Maver W: FB-80
Grinder: H: Super Jolly W: Brasilia...
Vac Pot: Hario TCA-2
Roaster: Sample Roaster at Work
Posted Wed Aug 8, 2007, 4:55am
Subject: Re: Up at the Sharp End by Alan Frew
 

Hi guys,

Just thought that I should put in a little reminder that this article was written four years ago!  (At the time of this posting ;P)

Cheers,

Luca

 
General ramblings about coffee: http://www.pourquality.blogspot.com/

Reviews of Australian coffee: http://www.coffeereviewaustralia.com/
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