Olympia Cremina Temperature Study, Part 1 - Page 2

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michaelbenis

#11: Post by michaelbenis »

Reiss of Londinium is absolutely right there in my experience. Flushing water through the Cremina is much less effective when you want to get the grouphead up to temperature either first thing or after the machine has been left idle for a while, especially in cold weather. The mechanics of this are explained nicely with a diagram here Olympia Cremina 2002: The evolution of design in Steve Robinson's excellent write up of the 2002 millenium and its predecessor.

Nice work, Dennis, in particular to have some figures confirming the Cremina really is an all-day-on machine.
LMWDP No. 237

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orphanespresso

#12: Post by orphanespresso »

Dennis...KUDOS on your work here. I do appreciate that you have asked specific questions oriented to your own user experience and gone about answering them. Very clearly presented and documented. Thank you very much!

As for the design differences of the new and older machines...perhaps covered elsewhere, but the reworking of the group to boiler seal is one main change and perhaps one that can be adapted to the older machines as well. The new group uses a full flange thick seal between the group and the boiler, much like the gasket on a commercial machine. This part could possibly be die cut from teflon sheet. The Olympia OEM part here is an open cell type white foam material rather than teflon but a thermal break here could bring the older machines more into line with the results you are getting....particularly the walk up and pull result...which is most interesting.

You did not mention that you broke your Mater pstat during this experiment....hope the new one gets things back in service so you can keep working on these temp experiments....why Olympia would go to the trouble of removing the pstat set screw and adding thread lock is beyond me!

Brilliant work.

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erics
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#13: Post by erics »

If anyone knows where to get such strip please let me know.
Sure, no charge :) , especially for all the work you did in creating this study - http://www.omega.com/ppt/pptsc.asp?ref= ... Nav=temf01

The part number for your desired range would be RLC-50-60/90-10 .
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

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peacecup

#14: Post by peacecup »

Leaving the machine on all day is not the problem - the group can dissipate the small amount of heat tranferred from the boiler when not in use. The tests demonstrate that the Cremina, like other home levers, overheats when multiple shots are pulled in succession. Overheating, and general temperature management when pulling multiple shots is THE major issue with any pressurized home levers.

They also show that by the time the group gets to 90C when the temp strip lights up, its more or less too hot to brew with. I have the same issue with the Sama. In fact, the group never gets hot enough to even show 90C. But since I like to brew at 90C, its obvious that the group needs to be be much cooler than that to act as a heat sink for the boiler water.

These tests are done with a relatively low p-stat setting - how is the milk steaming with the Cremina at this setting?

PC
LMWDP #049
Hand-ground, hand-pulled: "hands down.."

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tekomino (original poster)

#15: Post by tekomino (original poster) »

farmroast wrote: ps. were the best shots in the basket temp. range you expected?
Yes, indeed. As long as I manage temperature so I hoover around 199°F +/- 2-3°F its good. But here is kicker really that has be surprised, for some coffee which were lightly roasted I had some killer shots when first bar was in blue so they were brewed way too hot at about 208°F. They did not taste burnt at all. That little nugget has me stumped.
Refuse to wing it! http://10000shots.com

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tekomino (original poster)

#16: Post by tekomino (original poster) »

summer wrote: Just for reference Dennis, is your Cremina a 2011?
Its 2011.
Refuse to wing it! http://10000shots.com

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tekomino (original poster)

#17: Post by tekomino (original poster) »

orphanespresso wrote: You did not mention that you broke your Mater pstat during this experiment....hope the new one gets things back in service so you can keep working on these temp experiments....why Olympia would go to the trouble of removing the pstat set screw and adding thread lock is beyond me!
Thank you Doug. You and Barb rock and I'll have something for you guys in the mail :wink:
Refuse to wing it! http://10000shots.com

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tekomino (original poster)

#18: Post by tekomino (original poster) »

erics wrote:Sure, no charge :) , especially for all the work you did in creating this study - http://www.omega.com/ppt/pptsc.asp?ref= ... Nav=temf01

The part number for your desired range would be RLC-50-60/90-10 .
Wow, Eric comes to save the day. Thank you so much Eric. You are THE master of Omega site. Not in million years would I have found that. Ordered!

Now I am excited to do another round of tests with these new strips so I can devise good method that we can use to pull shots at right temp range. Thanks again Eric.
Refuse to wing it! http://10000shots.com

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tekomino (original poster)

#19: Post by tekomino (original poster) »

peacecup wrote: They also show that by the time the group gets to 90C when the temp strip lights up, its more or less too hot to brew with. I have the same issue with the Sama. In fact, the group never gets hot enough to even show 90C. But since I like to brew at 90C, its obvious that the group needs to be be much cooler than that to act as a heat sink for the boiler water.
I observed exactly same with PVL I had. I think PVL and Sama work little differently. The group might be more massive?
peacecup wrote: These tests are done with a relatively low p-stat setting - how is the milk steaming with the Cremina at this setting?
So mine hovers at 0.75-0.9 bars. Steams fantastic.
Refuse to wing it! http://10000shots.com

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peacecup

#20: Post by peacecup »

The 60-90 strips indeed look very promising. I'm going to need some of those also.

PC
LMWDP #049
Hand-ground, hand-pulled: "hands down.."