Londinium Compact. - Page 25

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mathof

#241: Post by mathof »

espressotime wrote:Tried that .Never noticed a difference.

That's interesting. It's the main point of the LR models.

Cuprajake

#242: Post by Cuprajake »

i thought the increased pi suited the lighter roast on a lr24 due to the temp increase the pressure increase caused?

baldheadracing
Team HB

#243: Post by baldheadracing »

RyanP wrote:The LR24 is made to keep on for long periods of time as a temp stable walk up and pull machine. The vectis is smaller with a quick 15 minute heat up meant for a couple of espressos before turning off. ...
pcdawson wrote:Regarding the 15 minute heat up......The Lever magazine's evaluation of the Cremina SL showed that it takes 1 hour for the group to stabilize at temp. This is the same as my experience with the SL group. As the Vectis has a similar if not larger group, I think 15 min is not enough time.
RyanP wrote:I was just quoting Reiss on that point.
To clarify, what was stated was, "15 minutes with flushing."
-"Good quality brings happiness as you use it" - Nobuho Miya, Kamasada

mathof

#244: Post by mathof »

Cuprajake wrote:i thought the increased pi suited the lighter roast on a lr24 due to the temp increase the pressure increase caused?
I believe there is meant to be a double effect from raising the PI pressure:
(1) from the higher pressure itself
(2) from the higher brew water temperature

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espressotime

#245: Post by espressotime »

mathof wrote: That's interesting. It's the main point of the LR models.
I don't have a Londinium.But you can apply every preinfusion pressure. you like with any lever.But maybe it's just me.
Could be the kind of beans I like.

Cuprajake

#246: Post by Cuprajake »

mathof wrote:I believe there is meant to be a double effect from raising the PI pressure:
(1) from the higher pressure itself
(2) from the higher brew water temperature
How though?

So the l1, LR and lr24 share the same boiler ,

If the boiler is set at 1.3 bar they would all infuse the same, but then you add the pump in the LR and lr24, does the pump take hot boiler water and push it at chosen bar say 3 or 4 and what does the pump pushing that pressure for 3-10s do to the water?

mathof

#247: Post by mathof replying to Cuprajake »

I can do my best to answer that from having read many discussions on this topic, but someone who understands these matters better is welcome to correct me.

The boiler on the LR and LR24 is set around 1 bar maximum. Unlike with the earlier L1, the boiler water is driven through the heat exchanger tube at the chosen pressure (up to 6 bar, I believe) and from there into the cylinder of the group, and on to the puck, which is pressurised/compressed accordingly. This procedure also compresses any air between the puck and the piston, causing a proportionately lower catch of the lever, leading to consequent higher initial spring pressure. As you say, without the pump, the earlier model infuses only at boiler pressure, which is accomplished by having the thermosyphon fed directly by the pressurised boiler water (rather than via an adjustable pump).

Rees maintains that the variable temperature of the brew water is influenced by the high pressure circuit: the lower the pressure driving the water through the mechanism, the longer it takes to reach the puck and the more heat it loses on the way. (Dave C has commented to my relating this in another forum that "this makes no sense at all". Probably I'm misrepresenting Reiss's explanation.)

mathof

#248: Post by mathof »

espressotime wrote:I don't have a Londinium.But you can apply every preinfusion pressure. you like with any lever.But maybe it's just me.
Could be the kind of beans I like.
The method is only intended for light and ultra-light beans. In addition, the flavours it is said to highlight would only be noticeable in straight espressos. If you were to add milk to espresso extracted from a very light bean with relatively high PI pressure, the subtle differences between it and espresso from the same bean pre-infused at lower pressures would probably not be apparent.

I should add that my Londinium is an early model that pre-infuses only at boiler pressure. I was never able to extract much from very light beans until I put Shuriken burrs in my Kafatek flat. Now that there is no problem obtaining quite high extraction yields from the lightest beans, I don't see how I would benefit from moving on to an LR model.

jamesz

#249: Post by jamesz »

pcdawson wrote: I think 15 min is not enough time.
You are right, Reiss said "15 minutes with a slow flush".

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espressotime

#250: Post by espressotime »

mathof wrote:The method is only intended for light and ultra-light beans. In addition, the flavours it is said to highlight would only be noticeable in straight espressos. If you were to add milk to espresso extracted from a very light bean with relatively high PI pressure, the subtle differences between it and espresso from the same bean pre-infused at lower pressures would probably not be apparent.

I should add that my Londinium is an early model that pre-infuses only at boiler pressure. I was never able to extract much from very light beans until I put Shuriken burrs in my Kafatek flat. Now that there is no problem obtaining quite high extraction yields from the lightest beans, I don't see how I would benefit from moving on to an LR model.
Exactly what I tried to say with my limited english knowledge.