La Marzocco GS3 - material of the brew group? - Page 2

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EspressoForge
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#11: Post by EspressoForge »

omega1848 wrote:May I ask one more question about the principles of the saturated group? If I understood correct, there is water flooding the "goose neck" up to the shower cap, correct? Hence saturated group. But I am struggling to understand how that works? Because if the boiler is not filled completely with water, how is it possible that the water from the brew boiler is travelling to the "goose neck" itself? Please note I am talking about the "saturated part", not the final water being pressed through the shower cap/ portafilter.
Or is the brew boiler always be filled 100% with water, but even then? Because the "goose neck" is higher from a physical location that the boiler...
Sorry I am confused!
Hope someone will be able to help!
Thanks!!!
The whole area (for the most part) in the picture above is flooded (saturated) with water up to about the threaded connections. More parts go in there, so not quite everything.

As Dan mentioned, a picture is worth way more than I will type:
Cutaway of La Marzocco saturated grouphead

Basic idea: more water contacts the group directly than previous designs which generally ran hotter boilers (for steam) and cooler groups.

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erics
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#12: Post by erics »

how is it possible that the water from the brew boiler is travelling to the "goose neck" itself?
Because, in the instructions, you are directed to bleed the small amount of air from the brew group via the M6 screw located on the top of the grouphead at first filling and any subsequent refilling. The brew boiler is thus filled to the "brink" with water. See P/N L120/2 below.

Skål,

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

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AssafL
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#13: Post by AssafL »

Bleeding the group at the very top (the bleed screw & copper washer/seal) is important not just so that the saturated group is heated appropriately - but since air is highly compressible it will change the pressure that the pump is trying to create in the system.

Once the area is saturated with water thermal gradients cause water to circulate to the group and back. It isn't as effective as a thermal syphon but it works pretty well since the ratio of water to steel is high (unlike an E61 which is huge and needs the syphon to try to keep it warm enough).
Scraping away (slowly) at the tyranny of biases and dogma.

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VeniaCoffee
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#14: Post by VeniaCoffee »

omega1848 wrote:May I ask one more question about the principles of the saturated group? If I understood correct, there is water flooding the "goose neck" up to the shower cap, correct? Hence saturated group. But I am struggling to understand how that works? Because if the boiler is not filled completely with water, how is it possible that the water from the brew boiler is travelling to the "goose neck" itself? Please note I am talking about the "saturated part", not the final water being pressed through the shower cap/ portafilter.
Or is the brew boiler always be filled 100% with water, but even then? Because the "goose neck" is higher from a physical location that the boiler...
Sorry I am confused!
Hope someone will be able to help!
Thanks!!!
These are dedicated brew boilers, no steam space and are filled 100% with water. When the machine is set up, there are bleed screws on top of each group that allow any air to escape.

omega1848 (original poster)
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#15: Post by omega1848 (original poster) »

Guys! Thanks so much! You rock!

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