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Permalink Reply by Don Berquist on April 1, 2009 at 12:53pm

Hello Terika,

Rancilio uses the same group and thermosiphon temperature stability system in all 2 group and larger machines. One small issue that would affect what follows is the year of manufacture.

As of January 2008, there have been significant changes to dial in the temperature even further. They include a shift away from a temp sensor for the steam tank which had an accuracy of +-0.5 degrees to a transducer with the same accuracy. The change is that the heating element turns on instantly when using steam. Also, the CPU activates the heating element the moment you push any button that dispenses water. This includes espresso or the hot water tap. This predictive logic stabilizes the steam tank temperature even further than before. One thing to remember is that all this is to only go after the last degree. The previous system was already highly refined. The Classe 6 models use a 6000 watt heating element which should be able to keep up with any environment, further stabilizing the system. A less powerful element will permit the tank to lower in temp during extremely high use. You must have this level of power for a single boiler machine to achieve this accuracy.

The group temperature stabilizing system is engineered to balance the group temperature based upon the steam tank temperature. This is one of the reasons why Rancilio breaks from the crowd and uses marine grade brass for the heat exchanger, not copper. There are 3 different sets of restrictors for this thermosiphon system that would effect a different temp based on a given steam tank temperature. Rancilio has used different restrictors based upon customers requests across the globe. It really is a simple yet ingenious system. Altitude over 6000 feet will affect the shot, as on any machine but this can be compensated for. Please let me know if this is the case.

If we assume you have a pre 2008 model and your tank pressure is set at the factory 1.0 bar setting, and that you have the most common restrictors used, your group temp should be around 202. This setting is not based upon lab results but rather the best simulation of a running shop using two types of portafilter based thermometers.

There is a jet in the group head itself, which along with the soft infusion head improves the shot quality but it does not affect the temperature of the shot.

If you are attempting to measure using any temp sensor not embedded in the group, like using a thermometer in a cup, you will find the temp on this machine to be like others, somewhere around 185-195.

I would suggest you make a small temp adjustment in the direction you would like and have five of your most discerning espresso drinking friends to critique the shot changes.

If I may help in any other way, please let me know.

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Permalink Reply by Stephen Curtis on April 1, 2009 at 4:42pm

Read this yet?

http://www.home-barista.com/hx-love.html

Still not exact - but it'll get you close. Darker roasts need a bit of a lower temp usually, so that would equate a longer flush. Lemme know if you're looking to go more in depth, as I've been down this road...

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Permalink Reply by Joshua Longsdorf on April 1, 2009 at 5:04pm

Using a scace would give you the most accurate read out for temp. I'm not incredibly familiar with these machines but it may be easier to lower you pressure 1/2 a bar or so and should give you similar results.

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Permalink Reply by Bryan Wray on April 1, 2009 at 5:47pm

For as many machines as you guys have, you definitely should invest in a Scace Device and a Fluke Thermometer. If you have never used one, it's amazing to find out how much your temperature can fluctuate on a HX machine like a Rancilio (not knockin' on ya, we use an old school HX too). The Scace device will give you a better idea of where your temperatures are running, though.

Clicky... and the thermometer page: Clicky

-bry

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Permalink Reply by Terika on April 2, 2009 at 5:36am

I was wrong, it is a classe 8.

Anybody in west Michigan have a scace that we could borrow? :)

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Permalink Reply by Joshua Longsdorf on April 2, 2009 at 1:42pm

Crema is a good thing, not sure if you were implying otherwise but kinda sounded that way, anyways the bubbling is from degassing. Try resting your espresso a few days and see if it helps. Also just because your machine is reading 9.5-10 bars doesn't mean this is the case. If you actually are at a higher atmospheric pressure then that could cause an increase in bubbling.

Jack Groot said:

Actually it is a Classe 8. Internally no different than a Classe 6. I have a Fluke and made my own set up to attempt to check temp stability (drilled two small holes in a blank, put the wires through one, and put it in the portafilter). The problem I had was knowing whether or not my test was a fair and accurate test for temp. And then also testing the temp over time or as it would be used in the field. I am not a scientist and don't have the time or temperament to do extensive testing.

Currently, I believe our pressure is set to .95 or 1. Our espresso blend is darker. The machine is a 2008 and we've had it for about 9 months to a year. I think it is post 1/08, but not sure. One issue we have been struggling with is bubbly crema and we are trying to eliminate variables in our testing. Freshness is definitely a factor we have addressed (and it has improved our shots), but we still see some crema that doesn't make us completely happy (some black flecking pushed to the edges) and have been wondering about blend darkness and temperature.

Also, I have heard that darker roasts require higher temps, not lower. Comments??

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Permalink Reply by Brady on April 2, 2009 at 4:53pm

I believe that Jack was indicating that he didn't like the look of their crema... understanding that its presence was a good thing. Agreed to the idea of getting to a good window for the age of their espresso (probably between 4 and 10 days), assume that's what Jack meant by "freshness issue".

Altitude should be a non-issue in Holland Michigan... though I believe that Yeshi intended to say that lower atmospheric pressure/higher altitude could cause increased bubbling.

Jack, when you refer to flecking pushed to the edges, do you mean black flecking or dark brown? I know for our blend, only when things are perfect do we get a beautiful dark-brown flecking... like this:

(Here's a pic from Sweet Maria's pictorial crema primer http://www.sweetmarias.com/espresso-crema.html that I love... this one looks perfect to me.)

I'm thinking that you don't mean that, right?

Good luck!

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Permalink Reply by Joshua Longsdorf on April 2, 2009 at 5:10pm

i was actually refering to bars as in the atmospheric bars or atmospheric pressure. My bad on use of terminology.

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Permalink Reply by Stephen Curtis on April 2, 2009 at 5:55pm

Hey Jack & Terika:

Everything I've read on HB and CG says dark roasts taste better with lower temps.

Your taste is what wins - so do what tastes best to you. If you're really interested I'd say start with dramatic differences. Flush for 5 seconds, pull & taste, then 10, 15, and so on. Or even 10 second increments. Then dial it in after you decide which tastes the best.

When it's busy you don't have to flush as long. You just start counting when the water dance ends - which will be pretty much non-existent when busy. If you want more control you may have to get another Aurelia, or a double boiler. As far as I know the Aurelia is the only HX machine that is quite temp stable. The problem with HX machines is when you're steaming a lot of milk, the boiler pressure drops, affecting the time needed in the actual HX to heat the water to brew temp. Easiest way - Get a machine that is known for temp stability. Most economical - get an emp who is detail orientated and have them map it out. Still isn't the same as when in use, but maybe similar if they were to use the steam wand as well.

If anyone has a Heat Exchange (HX) machine (most commercial machines are) this article is a Must Read:http://www.home-barista.com/hx-love.html

Echoing what Brady said: 4-10 days rest for espresso - extra bubbles can mean too fresh

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Permalink Reply by Bryan Wray on April 2, 2009 at 6:57pm

Jack Groot said:

Actually it is a Classe 8. Internally no different than a Classe 6. I have a Fluke and made my own set up to attempt to check temp stability (drilled two small holes in a blank, put the wires through one, and put it in the portafilter). The problem I had was knowing whether or not my test was a fair and accurate test for temp. And then also testing the temp over time or as it would be used in the field. I am not a scientist and don't have the time or temperament to do extensive testing.

Currently, I believe our pressure is set to .95 or 1. Our espresso blend is darker. The machine is a 2008 and we've had it for about 9 months to a year. I think it is post 1/08, but not sure. One issue we have been struggling with is bubbly crema and we are trying to eliminate variables in our testing. Freshness is definitely a factor we have addressed (and it has improved our shots), but we still see some crema that doesn't make us completely happy (some black flecking pushed to the edges) and have been wondering about blend darkness and temperature.


Jack, this is something I would like to talk with you about in person, perhaps in Atlanta when we meet up. I know you aren't sure about transportation down there, but I think we should plan on setting up a time to meet (perhaps at Octane?). Just observations about your blend, it's roast, etc. It would get way too long to type up online.

When you say you have been wondering about blend darkness are you referring to possibly changing the darkness of the blend? Or are you referring to how temperature correlates to the degree of darkness.

Darker=cooler, for sure. With your blend being as dark as it is I would definitely say start going cooler.

-bry

Also, I have heard that darker roasts require higher temps, not lower. Comments??

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Permalink Reply by Bryan Wray on April 4, 2009 at 4:04pm

Whoa... weird post. I just went back and read it. Sorry to include what I wanted to say inside of your quote. Anyway, my reply is in there, haha.

-bry

Bryan Wray said:

Jack Groot said:

Actually it is a Classe 8. Internally no different than a Classe 6. I have a Fluke and made my own set up to attempt to check temp stability (drilled two small holes in a blank, put the wires through one, and put it in the portafilter). The problem I had was knowing whether or not my test was a fair and accurate test for temp. And then also testing the temp over time or as it would be used in the field. I am not a scientist and don't have the time or temperament to do extensive testing.

Currently, I believe our pressure is set to .95 or 1. Our espresso blend is darker. The machine is a 2008 and we've had it for about 9 months to a year. I think it is post 1/08, but not sure. One issue we have been struggling with is bubbly crema and we are trying to eliminate variables in our testing. Freshness is definitely a factor we have addressed (and it has improved our shots), but we still see some crema that doesn't make us completely happy (some black flecking pushed to the edges) and have been wondering about blend darkness and temperature.


Jack, this is something I would like to talk with you about in person, perhaps in Atlanta when we meet up. I know you aren't sure about transportation down there, but I think we should plan on setting up a time to meet (perhaps at Octane?). Just observations about your blend, it's roast, etc. It would get way too long to type up online.

When you say you have been wondering about blend darkness are you referring to possibly changing the darkness of the blend? Or are you referring to how temperature correlates to the degree of darkness.

Darker=cooler, for sure. With your blend being as dark as it is I would definitely say start going cooler.

-bry

Also, I have heard that darker roasts require higher temps, not lower. Comments??

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