# What is a saturated group?



## Obnic

I'm a bit embarrassed to say I don't know this but I've always had E61 machines. Please could someone explain what a saturated group is and what are the benefits? Cheers.


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## 4085

La Marzocco use them and from memory, it is a way of heating the group so that it is ready much faster than an E61......a bit like the Sage cartridge system, but, it also delivers water into the group head in a more controlled way. Interesting thread here

http://www.home-barista.com/espresso-machines/cutaway-of-la-marzocco-saturated-grouphead-t700.html


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## Obnic

Ha. Group head is integral to the boiler then rather than using a thermosyphon. Makes sense. Superior temperature stability would be the objective then.


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## hotmetal

I'm not the right person to explain really, but as I understand it the idea is to have the brew water circulating freely into the group almost as if it was part of the brew boiler. It's said to give better thermal stability, although personally I'd have thought the E61 (on a DB machine with a PID) would be better for that due to the thermal inertia of a huge lump of brass. Maybe what they mean is that it's more readily controlled by the PID as the water can change temp faster but should be almost identical to the temp of the rest of the brew boiler? I suppose it would heat up quicker and be faster to change temperature than e61. Also you have a solenoid instead of the lever cam gubbins. Here's a thread I saw that isn't strictly the answer to your question but does have a cutaway and diagram so you can get the idea. I dare say there must be cons as well as pros to this solution like everything.

That said, saturated group machines include serious kit such as KvdW, the GS/3, Synesso etc.

http://www.home-barista.com/espresso-machines/cutaway-of-la-marzocco-saturated-grouphead-t700.html


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## hotmetal

D'oh! Beaten to it while typing :-/


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## DavecUK

Saturated groups would be slightly more sensitive to overshoots, but have a smaller offset than that of an E61 group. The E61 group has a very large thermal mass, which makes it less efficient and possibly slightly more prone to undershoot. Either way, I can't taste the difference.


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## Mrboots2u

Then aren't there groups like the Sage and Bezerra which have a coil that keeps it at temp? Not saturated but not E61


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## MediumRoastSteam

And, what are the groups of a Rancilio Silvia and the one of a Gaggia Classic called? Are they also saturated?


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## Mrboots2u

pessutojr said:


> And, what are the groups of a Rancilio Silvia and the one of a Gaggia Classic called? Are they also saturated?


No they are not-


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## Xpenno

Sage is similar-ish. The brew boiler is pretty much integrated into the group so the water doesn't travel far so small offset applies. Water passes through the steam boiler on the way to brew boiler so arrives pre heated so less work for the brew boiler. Finally the group has electric heaters to get the block up to temp.

Real saturated groups are integrated with the boiler so they run at a similar temp for max stability. Also the path that the water takes from the brew boiler passes through a pipe immersed in this water so it doesn't cool, hence the low offset.


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## hotmetal

Well this has turned out to be quite informative and had certainly fleshed out my vague understanding of the pros, cons and idea behind the design. Especially the undershoot vs overshoot which I hadn't considered when thinking about PID and adjustability of each design.

Another saturated group could be a bus load of coffee nerds that turned up for a tour of the La Marzocco factory on the wrong day and had to stand out in the rain.

Sorry, that was specially for @grumpydaddy. Apologies for exposing the more sensible amongst you to my dodgy puns.


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## Zeak

Mrboots2u said:


> No they are not-


Sorry for resurrecting this thread, but I've started reading on E61/HX/DB etc etc and from what I've read Gaggia's grouphead can be classified as a saturated group. Otherwise what is it? Or am I wrong?



> A saturated group, on the other hand, pulls water from a dedicated and thermally controlled water source.


from Clive Coffee


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## Stanic

Gaggia, Silvia, Profitec 300 etc. use the so called ring group, chunk of metal bolted to the boiler, there is no room for water to circulate within the group, compared to the typical saturated ones

They have a fast warm-up and the thermal stability seems to be fine when controlled by a PID


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## Zeak

Stanic said:


> Gaggia, Silvia, Profitec 300 etc. use the so called ring group, chunk of metal bolted to the boiler, there is no room for water to circulate within the group, compared to the typical saturated ones
> 
> They have a fast warm-up and the thermal stability seems to be fine when controlled by a PID


Ah here you go! Thanks mate! I've Googled for a good hour in order to find any mention of the type to no luck.


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## Stanic

Just Google some parts diagrams and it'll be very clear


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## 4085

of course, the short answer, is bloody expensive


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## ajohn

The Piccino uses one so if anyone wants to see how it's arranged look at the parts listing. It also shows the tube. They also insulate the actual boiler so most heat loss is through the head







Probably would be anyway due to the heat from the steam boiler. It still takes circa 15min to get the grouphead hot, Better than thermosyphon but still slow. Having looked around at their commercial range they also seem to use the same arrangement as a group head heater on some multihead machines.

Ascaso seem to have a new model that uses a 2 thermoblock arrangement. One for steam and the other for brew. Not sure which gives hot water. The cup warmer is powered separately and the thermoblocks look to be insulated. Unlike Sage tt also seems to use an all metal group head very probably with the usual E61 arrangement. Of interest to me if I could find any hard information on it. Pictures yes but no one I can find around the UK actually has one. Might be the answer to quick heat up. On the other hand maybe no better than machines like the Piccino.

John

-


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## ajohn

Here's a screenshot of the one in the Piccino
















Hope it's big enough

John

-


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## J_Fo

Obnic said:


> I'm a bit embarrassed to say I don't know this but I've always had E61 machines. Please could someone explain what a saturated group is and what are the benefits? Cheers.


The most well known saturated group are Wet Wet Wet.

I'm so sorry.


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## Drewster

Jon_Foster said:


> The most well known saturated group are Wet Wet Wet.
> 
> I'm so sorry.


You should be!!!

Hang your head in shame...


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## Rhys

Drewster said:


> You should be!!!
> 
> Hang your head in shame...


I felt that comment in my fingers, and I felt it in my toes.....

...OK I'm getting my coat


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## Stanic

A picture is worth a thousand words







a quick grab from the manufacturer's video showing a schematic cross section of the KVdW Speedster's hydraulic system and their take on saturated group head









And for comparison the ring group of Rancilio Silvia, easily visible here:


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## Stanic

and just to add

this is the scheme of the LM gs3 saturated group and boiler









Synesso MVP Hydra









and from the Slayer's website


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## Stanic

I think I read somewhere the point is to have a good circulation of water within the whole system and the neck design is very important to facilitate the flow


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