# How does the Londinium L1 actually work?



## JackBlackmore (Nov 1, 2015)

Ahead of the impending Londinium L1 purchase I thought I should do some research to find out how they actually work. So far all I've managed to find is reams of people quoting "smooth", "creamy" and "stable" but nothing on the actual internals (to be fair I haven't looked that hard)

I've finally got to the point where I understand how my E61 works but could anyone point me in the direction of any diagrams on how the internals / grouphead of the Londinium's function?


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## coffeechap (Apr 5, 2012)

https://www.google.co.uk/search?client=safari&hl=en-gb&ei=FpYhWLiFFsz_aZ27rYgP&q=+londinium+l1+diagram&oq=+londinium+l1+diagram&gs_l=mobile-gws-serp.3...57579.70208.0.71012.23.22.1.2.2.0.205.2761.3j16j1.20.0....0...1c.1.64.mobile-gws-serp..1.20.2346.3..0j35i39k1j0i131k1j0i10k1j0i22i30k1j33i21k1.nweeiopyHxM

You are right you don't look that hard


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## Split Shot (Sep 24, 2016)

I found this to be the clearest illustration of the Group cross section. You'll have to use 'Google Translate' as it's in German, but it works very well.

https://www.kaffeewiki.de/index.php?title=Handhebelbr%C3%BChgruppe

NB. I'm not convinced that 'Stroke Volume' or 'Mass in Cup' is a hard limit - it isn't in practice.


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## JackBlackmore (Nov 1, 2015)

Well I never! So there is a thermosyphon that circulates boilerwater around the grouphead to get it to the correct temperature and then when you pull the leaver it compresses the spring, pulls up the piston and opens the chamber that the cooled breadhead water enters into and then when you release the lever the spring pushes the piston down and the water is pushed through the puck?

Without having any idea it's easy to assume that when you pull the lever down you're pushing water through the puck rather than compressing the spring. Starting to get pretty excited


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## Thecatlinux (Mar 10, 2014)

When you pull lever down you are allowing water into the group (above your coffee) and compressing the spring . When you release the lever the spring then pushes the piston down forcing the water through the coffee.

Tried to keep it as simple as possible for you ,

although it it may look intimidating it's actually quite easy to use and matched with a good grinder and good beans you'll soon be able to produce amazing espresso at home .


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## mathof (Mar 24, 2012)

I don't understand something about this diagram. If you look inside the L1, you will see two pipes, one above the other, leading into the group neck. In this picture all we see is a blue blob from which one channel descends. The water then seems to rise in the centre of the neck and flow around a white disk and then descend to fill a small ring inside the group. From there, when the piston rises, it will enter the chamber (through the four holes in the sleeve). But there is no indication of a return path for the water that is circulating in the sleeve to the boiler. What am I missing? Thanks.

Matt


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## Split Shot (Sep 24, 2016)

Good eyes.

I'm a very recent lever owner, and I got confused by this also whilst doing my research.

If it helps...

You'll find that different machines implement virtually the same group - often referred to, but not actually made by, "Bosco" - but in different ways.

One common way is a "dipper" where the group is bolted directly onto the boiler and is heated by direct heat transfer (through the metal). This might have just one connecting pipe for brew water as per the drawing you refer to.

Londinium don't do this. The group isn't directly bolted onto the boiler. The group is heated by water circulating through a "thermosyphon". Hence two pipes connecting it to the boiler. You can see this on a hand drawn image found easily via the link @coffeechap provided above.

Try reading this:

http://www.home-barista.com/levers/salvatore-lever-vs-londinium-dipper-vs-thermosiphon-t34809.html#p394733

Actual Bosco machines are slightly different again...

I'll let others far more knowledgeable than me provide a better explanation if they want....


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## mathof (Mar 24, 2012)

Ah, thanks. The coffeechap diagram is different and very clear. It seems that the giant group is heated by a small ring of water within it at the level of the bottom of the neck and by conduction from the neck itself, transferring the heat generated within it by the thermosyphon. No wonder it takes forever to heat up the group sufficiently from room temperature.

Matt


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## Split Shot (Sep 24, 2016)

I wouldn't jump to that conclusion necessarily. You can heat an L1 up to temperature in 12 minutes, apparently, by using some big flushes. Because of the way the L1 is engineered you can flush large amounts of very hot water in one go. But this is essentially just dumping the boiler contents through the group, heating up again and then repeating...

Much better to use a Wemo and let it idle for an hour IMO. Flushing it hot doesn't sound like "thermal stability" to me!

What you want is a massive group, at the correct temperature, which is exactly what the Londinium has if you give it time.


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## mathof (Mar 24, 2012)

Yes, all that is true. In fact, I do use a Wemo but my kitchen is cold in the morning at this time of year, so I give it about three hours, just to be sure the group is heated through and through. I want that first cup to be good.

Matt


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## Thecatlinux (Mar 10, 2014)

Warm up time is not an issue


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## aaronb (Nov 16, 2012)

My kitchen can get cold overnight, L1 is easily up to temp in 45-60 mins.

As said you can get that down to 15 or so with a flush.


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## 4515 (Jan 30, 2013)

The quick answer to 'how does an L1 work' is

really well

Buy one - you'll love it !


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## Tewdric (Apr 20, 2014)

I can get a good cup 5 minutes from switch on, if I have to, from my L1.


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## JackBlackmore (Nov 1, 2015)

It's basically a saturated group head and a relatively small boiler so warm-up time should be super low


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## The Systemic Kid (Nov 23, 2012)

2.3ltrs capacity isn't relatively small.


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## Mrboots2u (May 10, 2013)

JackBlackmore said:


> It's basically a saturated group head and a relatively small boiler so warm-up time should be super low


It is not a saturated group or a small boiler. The large group is helping regulate the temp for instance .


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## JackBlackmore (Nov 1, 2015)

Mrboots2u said:


> It is not a saturated group or a small boiler. The large group is helping regulate the temp for instance .


From what I was reading I was (incorrectly it seems) under the impression that the thermosyphon water surrounded the piston / brewchamber inside the grouphead?


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## Dylan (Dec 5, 2011)

JackBlackmore said:


> From what I was reading I was (incorrectly it seems) under the impression that the thermosyphon water surrounded the piston / brewchamber inside the grouphead?


To be fair a saturated group has a lot of similarities to a dual boiler machine. Rather than have a pipe going to and from the group however it is more like the group is simply part of the whole brew boiler. It also gets its stability from being 'saturated' in the brew water, not from its metallic thermal mass like an e61.

If you take a look at this: http://www.home-barista.com/espresso-machines/cutaway-of-la-marzocco-saturated-grouphead-t700.html

It may give you a better idea of what a saturated group looks like.


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## JackBlackmore (Nov 1, 2015)

Aye I've seen that thread before it's just understanding the internals of the lever that seem to escape me. It's not mounted on the boiler and heats up mighty quick so not in the same principle as the e61 so I assumed it must be surrounded by the thermosiphon water, I understand it's not saturated in the LM sense but couldn't think of a better term for this.

What Id like is for someone to just chop their lever in half if there are any takers?


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## dsc (Jun 7, 2013)

mathof said:


> Yes, all that is true. In fact, I do use a Wemo but my kitchen is cold in the morning at this time of year, so I give it about three hours, just to be sure the group is heated through and through. I want that first cup to be good.
> 
> Matt


Leave it on 24/7, its then ready to go whenever you want a coffee.

T.


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## The Systemic Kid (Nov 23, 2012)

JackBlackmore said:


> It's not mounted on the boiler and heats up mighty quick so not in the same principle as the e61 so I assumed it must be surrounded by the thermosiphon water, I understand it's not saturated in the LM sense but couldn't think of a better term for this.
> 
> What Id like is for someone to just chop their lever in half if there are any takers?


Think you'll be waiting a long time for that!

Advantage of the group not being mounted directly on to the boiler is temp stability when pulling several shots in a row. Boiler mounted groups over-heat and need to be cooled down. Not so the Londinium - it's very temp stable thanks to the design, employment of a thermosyphon and grouphead mass of several kilos. You can happily leave it on all day and it won't overheat and need purging shots. The 2.3ltr boiler won't burn a pocket electricity bill-wise, either.


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## mathof (Mar 24, 2012)

JackBlackmore said:


> From what I was reading I was (incorrectly it seems) under the impression that the thermosyphon water surrounded the piston / brewchamber inside the grouphead?


The piston is surrounded by ring of water inside the grouphead, as can be seen in the images that coffeechap posed earlier in this thread: http://www.home-barista.com/forums/userpix/269_lon_gp1b.jpg

Matt


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## Dylan (Dec 5, 2011)

The Systemic Kid said:


> Think you'll be waiting a long time for that!
> 
> Advantage of the group not being mounted directly on to the boiler is temp stability when pulling several shots in a row. Boiler mounted groups over-heat and need to be cooled down. Not so the Londinium - it's very temp stable thanks to the design, employment of a thermosyphon and grouphead mass of several kilos. You can happily leave it on all day and it won't overheat and need purging shots. The 2.3ltr boiler won't burn a pocket electricity bill-wise, either.


Patrick - Is the boiler of an LM saturated group not mounted directly to the boiler? Is it not temp stable? Why would having a group not mounted to the boiler make it temp stable?


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## JackBlackmore (Nov 1, 2015)

I'm pretty sure it's on a dual boiler machine so you can easily control the temps without affecting steam performance whereas the Londinium is closer to a HX / Single boiler


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## The Systemic Kid (Nov 23, 2012)

Dylan said:


> Patrick - Is the boiler of an LM saturated group not mounted directly to the boiler? Is it not temp stable? Why would having a group not mounted to the boiler make it temp stable?


Was referring to other lever machines' design, Dylan not to, say, an LM design.


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## Dylan (Dec 5, 2011)

The Systemic Kid said:


> Was referring to other lever machines' design, Dylan not to, say, an LM design.


I see, easy to misinterpret I think, especially as with some designs being mounted directly to the boiler is the very reason they are stable!


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## lespresso (Aug 29, 2008)

mathof

if your L1 is taking 3 hours to get up to temperature the anti-vac valve is no longer performing its task and needs to be replaced

kind regards

reiss.

___________________________________________________________________________________________________________

general comment - some will scoff, but by definition it is a saturated group head... all the way from 1950. so not really new tech at all. annoying.


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