SPRING Lever Espresso Machine types - defined - Page 3

#21: Post by **JB90068** » January 28th, 2023, 8:01 pm

Great thread especially for those of us who are researching endgame levers. Thank you.

#22: Post by **FotonDrv** » February 5th, 2023, 1:01 pm

RistrettoCapp wrote:I'm just entering the world of spring lever machines, and haven't found any clear definition of the three types: Dipper, Thermosiphon and saturated (are there others?)

I've searched the forums but search doesn't return anything related to defining these types.

Can you spring lever gurus, and users, chime in and define each one of these types, along with their pros and cons?

ADDING DEFINITIONS AND INFO UPDATES HERE FOR FUTURE READERS:
Dipper groups:
Bolted directly to steam boiler, draws in steam boiler water that is hotter than needed and cools, by way of the group-head absorbing/radiating heat, to the correct brew temp.
Subsequent 'flushes' will INCREASE the brew temp, by increasing the group temp.
Video here showing a Dipper Group-head: https://www.baristahustle.com/lesson/em ... -machines/
EXAMPLES:
Profitec pro 800 - with added PID and vibe pump to fill the boiler from the pour over tank
Pompei or Nuova Pompei by Izzo
Alex Leva by Izzo
Bosco Sorrento
Salvatorre machines (CMA group?)

Thermosiphon groups:
Thermosiphon groups use two thermosiphon pipes (a feed pipe and a return pipe) to circulate water from one end of the heat exchanger, around the group with a water jacket behind the sleeve, and back to the heat exchanger via the return pipe of the thermosiphon to be heated up again. It is a passive method of heat exchange, based on natural convection, without the necessity of a mechanical pump. Thermosiphon groups can be mounted away from the steam boiler because they are only 'connected' hydraulically via the Thermosiphon loop pipes.
Subsequent 'flushes' on a Thermosiphon or HX group, will DECREASE the brew temp as fresh, cooler water is drawn into the HX tube AND/OR the group absorbs/radiates heat from the water
EXAMPLES:
Londinium R24
Quick Mill Veloce
Salvatorre machines (VBM group?)

Saturated groups:
Saturated lever groups, like their pump counterparts, are connected directly to a brew boiler and have brew water encasing the group to maintain thermal stability. The main differences between Saturated and Thermosiphon group types is that Saturated groups use Brew Boiler water (Thermosiphon groups run water from the Steam Boiler through the group-head) and Saturated groups are always connected directly to the brew boiler - they are typically PID controlled as well.
Subsequent 'flushes' have no effect on the temp of shots, as the boiler water, group-head and brew water are all maintained closely to the same temp.
EXAMPLES:
Kees van der Westen Slim Jim Idrocompresso

Actively Heated groups:
A newer technology that replaces previous methods of heating the lever group with cartridge or other active heating elements. These are usually used on Dual Boiler, PID controlled machines that maintain the brew boiler temp accurately. Actively heating the group-head allows for even finer control of brew temps as the user can, usually, control the brew boiler temp via PID AND the group-head temp separately.
Subsequent 'flushes' have no effect on the temp of shots, as the boiler water, group-head and brew water are all maintained closely to the same temp.
EXAMPLES:
Nurri L-type Leva (PID controlled dual boiler leva with an actively heated group)
Bezzera Strega

Where does the Lapera fit into this array of Lever Machines? To me it appears to be a hybrid between HX and Saturated.

February 5th, 2023, 1:25 pm

It's uses a HX, like the Bezzera Strega or Victoria Arduino Athena Leva. (The Victoria Arduino White Eagle Leva is, I believe, a multi-boiler.)

The taxonomy conflates how the group is heated with how the brew water is heated.

February 5th, 2023, 2:14 pm

Being that the Lapera has the Group bolted directly to the boiler had me asking the question. The HX tube through the boiler speaks for itself.
Is it a thermosyphon heat through the HX tube?

February 5th, 2023, 2:42 pm

No thermosyphon for the Lapera/Brugnetti or VA Athena or Strega, etc. The HX is only fed by cold line-pressure water.

#26: Post by **FotonDrv** » February 5th, 2023, 6:46 pm

is the PID monitoring the Group temperature or the boiler temp?

February 5th, 2023, 9:10 pm

Boiler, with a pressurestat in-line as a fail-safe.

February 5th, 2023, 9:47 pm

Thank you.

#29: Post by **Jake_G** » February 6th, 2023, 7:23 am

Craig,

Doesn't the Lapera also have a small reservoir at the top of the HX that the brew water is drawn from?

I recall Thomas doing lots of thermometry getting the HX design and the cold water injector tuned correctly so that as the group warmed up after a shot, the reservoir cooled down so that the second shot would have the same temperature profile as the first. Am I remembering that correctly?

Given the range of HX machines, I think the taxonomy in the first post could use a bit of a refresher.

You have two major groupings:

Boiler (Steam Pressure) Fed
Mains or Pump Fed (HX or DB)

Within group 1, you have the following machine types:

Dipper:
-Bosco, Pro 800, Clubs, etc
Thermosyphon:
-Lambro, Londinium L1, etc
Saturated:
-Faemina, etc

And within group 2:

Direct HX:
-VA Athena, Lapera, LSM
Inderect HX:
-Bezzera Strega
Thermosyphon HX:
-Londinium Compressa/R/R24
Double Boiler Saturated:
-LM Leva X, KVdW Slim Jim
Double Boiler Dipper:
-ACS Vostock/Evo Leva, Nurri Leva, Curtis' Double Dipper

RistrettoCapp wrote:If so, with the brew boiler PID controlled wouldn't that turn this con into a pro - in that the grouphead would be at the same temp as the boiler?

Youd think so, but in practice, the double boiler and indirect HX machines are the ones that tend to use heated groups, with the Strega, Leva X, ACS machines for sure employing it. Double boiler gives you a steady supply of brew water, but lever groups are big and shed heat, so active heating plays a role of you have cooler water feeding them.

Cheers!

- Jake

February 6th, 2023, 12:56 pm

Jake_G wrote:Craig,

Doesn't the Lapera also have a small reservoir at the top of the HX that the brew water is drawn from?

I recall Thomas doing lots of thermometry getting the HX design and the cold water injector tuned correctly so that as the group warmed up after a shot, the reservoir cooled down so that the second shot would have the same temperature profile as the first. Am I remembering that correctly?

Yes. The Brugnetti used either a horizontal "horseshoe" HX or a diagonal HX tube. Thomas experimented with quite a bit with the horseshoe before switching to the diagonal.

The horizontal HX had to run its output back to the group. The Brugnetti's group is mounted to the boiler and so looks like a dipper from the outside. However, in this case the inside of the mount is only open to the back of the group. There is no opening to the boiler; the space inside forms a reservoir that receives the water from the horseshoe HX. The horseshoe HX was abandoned in favour of the diagonal HX (by both Brugnetti and Lapera).

Like the horseshoe HX, from the outside the group mount for the diagonal HX looks like the group is mounted to the boiler like a dipper. However, the inside of the boiler neck is not connected to the boiler water - the neck is an extension of the diagonal HX tube. Thomas calls this neck area a "reservoir" - which it definitely was with the horizontal HX.