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Cutaway of La Marzocco saturated grouphead

Postby HB on Thu Nov 03, 2005 9:11 am

Often you'll hear the term "saturated group" bandied about, usually in the context of explaining the advantages of dual-boiler designs like La Marzocco's. But a picture is worth a thousand words:

Image
"Gooseneck" extends the grouphead away from the boiler to the service area

Image
Closeup of the grouphead itself; notice the copper water inlet

Thanks go to the folks at Counter Culture Coffee who use this cutaway as part of their barista training course.
Dan Kehn
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Postby malachi on Thu Nov 03, 2005 12:37 pm

Fantastic photos.

Keep in mind that this is the semi-auto version...
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Postby barry on Thu Nov 03, 2005 4:20 pm

malachi wrote:Fantastic photos.

Keep in mind that this is the semi-auto version...



what's the difference between the one shown and the full-auto version?


--barry "btw, it's missing the diffuser"
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Postby malachi on Thu Nov 03, 2005 4:52 pm

Hunh
Actually... now that I look at the picture more carefully I don't think there is any difference.
The differences are all independent of the group I guess.
I stand corrected.

Are there any differences between the old, bolt on and the new, welded on groups?
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Postby malachi on Thu Nov 03, 2005 4:53 pm

Does the diffusion block just screw into those threads?
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Postby malachi on Thu Nov 03, 2005 4:55 pm

Oh... and I think now folks can see why:

1 - I prefer this design to the E61,
2 - Why I loved (in theory) the Hybrid group,
3 - and why that Hybrid group was (as Barry says) a total PITA to service.
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Postby barry on Thu Nov 03, 2005 5:13 pm

malachi wrote:Actually... now that I look at the picture more carefully I don't think there is any difference.
The differences are all independent of the group I guess.
I stand corrected.


i just wanted to be sure i wasn't missing anything. ;)


Are there any differences between the old, bolt on and the new, welded on groups?


apart from the stainless? i don't think so. i had someone tell me there was a change in the banjo tube/bolt interface, but they weren't able to describe it as anything other than "a change" and no one i've talked to who has a welded group has been able to verify that change. ask bill c. ;)
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Postby HB on Thu Nov 03, 2005 6:27 pm

malachi wrote:Oh... and I think now folks can see why... I prefer this design to the E61.

For those who joined late in the discussion, below is an excerpt from Lino's E61 Group Espresso Machine: Detailed Interior Schematics:

Image

Cross Section, lever and valves in brew position (courtesy Verna Design Inc., please do not copy)

Comparing the two, you can see that the grouphead and indeed the backside of the La Marzocco dispersion block works as a direct extension of the boiler (hence why they call it "saturated"). In contrast, the E61 relies on circulation tubes leading to/from the boiler to bring water heated by the steam boiler to the grouphead and return cooler water (hence why it's called a "thermosyphon" and forms part of the HX circuit). The low-level details were covered in E61 Group Espresso Machine: Is its reputation justified?

That said, Chris will readily admit the La Marzocco design isn't without its own compromises. Ask him about the flowmeters on the automatics. Go ahead. I dare you.
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Postby barry on Thu Nov 03, 2005 6:36 pm

HB wrote:That said, Chris will readily admit the La Marzocco design isn't without its own compromises. Ask him about the flowmeters on the automatics. Go ahead. I dare you.


or the solenoids on either.


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Postby barry on Thu Nov 03, 2005 6:37 pm

malachi wrote:Does the diffusion block just screw into those threads?


yes, with a gasket between.
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