SPRING Lever Espresso Machine types - defined

December 29th, 2022, 10:32 pm

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

#2: Post by **daveyb** » December 30th, 2022, 4:04 am

Greetings, the three things you refer to are not limited to spring levers. They actually refer to the method used of heating the hot water and delivering it to the group head.
Dippers in a non technical explanation, are where the boiler bolts directly onto the group head, making the control of water temperature all but impossible. This means you need a cooling flush. once warmed up if you draw water out the boiler has it at steam temperature and it 'fizzes'.
A thermo syphon kind of sits between the boiler and group and is a way of regulating the water temperature. It is successful to a degree but you need the intervention of a pid or other electronics to accurately control it.
A saturated head I am not really able to explain so someone else can chip in! I think that your choice would be made easier if you did the following. Set a budget, then decide if you want a single boiler machine or a dual boiler. A dual boiler has 2 boilers, one for producing steam and one for producing water for the espresso. A machine like the ACS Evo Leva is a dual boiler sprung lever machine wiht electronics to control temperature of both boilers and the group head , the latter using heat cartridges.
Everyone will have their own favourite system of course! Personally, I would steer clear of the dipper arrangement unless you like to guess! The thermosyphon is old technology, but read as much as you can!

#3: Post by **Primacog** » December 30th, 2022, 4:58 am

RistrettoCapp wrote:I'm just entering the world of spring lever machines, and haven't found any clear definition of the three types: Dipper, Thermosyphon 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?

I assume you are referring to single group spring levers that home enthusiasts would be interested in.

Those classifications you have proposed seem to me to be ways in which an espresso machine's temperature is regulated or controlled (or not) and as daveyb mentioned, are not specific to lever machines but can be applicable to pump machines as well. Thus they wouldn't be as useful as a means to classify different types of spring levers in my opinion.

It seems to me that one useful way to differentiate between different kinds of home spring levers can be to divide them into traditional non-grouphead temperature and/or preinfusion pressure adjustable designs, and on the other hand, more contemporary grouphead temperature adjustable and/or preinfusion adjustable designs. Those parameters enable the machines to be able to be adjusted more easily to suit lighter roasts.

Within the first category are the vast majority of spring levers such as vintage levers and such modern machines as izzo pompei and Alex, profited pro 800 (its PID can only control the temperature of the boiler and not the groiphead directly and separately) etc.

In the second category can be divided into two sub categories- the first where only the preinfusion pressure can be directly manipulated and the second where both the preinfusion pressure and the grouphead temperature xan be independently manipulated. As far as i can recall, the Londinium R24 may be the only representative of the first subcategory thta I am aware of, while the second sub category has the LM LEVA X single group machine, the acs vesuvius evo, and the Nurri L-type SA Machine. There is also an upcoming commercial oriented machine from acs called the vostok that will also be available in single group format. While the LM LEVA X controls the grouphead temp through having a saturated grouphead, both the vesuvius evo (and vostok) and the Nurri use cartridge heaters to independently heat up the grouphead which can be controlled through the PID. The vesuvius evo uses a gear pump to control the preinfusion pressure while the nurri uses a rotary pump to do so.

#4: Post by **Cuprajake** » December 30th, 2022, 7:10 am

Vostok 1 group will be for home use.

Believe near same dimensions as the nurri, bigger than the Evo leva and bigger again than the lr24, which I think may be the smallest of the bunch, not sure on the profitecs size

#5: Post by **JohnB.** » December 30th, 2022, 8:25 am

daveyb wrote: Dippers in a non technical explanation, are where the boiler bolts directly onto the group head, making the control of water temperature all but impossible. This means you need a cooling flush. once warmed up if you draw water out the boiler has it at steam temperature and it 'fizzes'.

There's no such thing as a "cooling flush" with a dipper. A flush will only raise the group head temp from it's idle temp as you are flushing with boiler temp water. A well designed dipper spring lever will allow you to easily select the shot temp you desire with a simple & quick warming flush.

#6: Post by **Cuprajake** » December 30th, 2022, 10:02 am

How do you know what temp that is?

December 30th, 2022, 10:16 am

Like a number of other traditional spring lever users I have a thermocouple on the side of the group which plugs into my Fluke temp meter. Having done extensive Scace testing when I got the machine I know what shot temps various group temps will produce. My Bosco's group idle temp is 171-172°F in a 72°F room with a 1.2 bar p'stat setting which produces a 198° shot temp. A 2 second flush will bump up group temp to 174-175°F which gives you a 200°F shot temp.

#8: Post by **Satchmo780** » December 30th, 2022, 10:35 am

daveyb wrote: A thermo syphon kind of sits between the boiler and group and is a way of regulating the water temperature. It is successful to a degree but you need the intervention of a pid or other electronics to accurately control it.

Not entirely correct. Thermospyhons are when the boiler is connected to the group by at least two pipes, set at different heights, thus enabling the grouphead to maintain a steady temperature as the water cycles through (cooler water sinking and all that), which makes the grouphead stay at a constant temperature ready for shots without warming flushes. They're not terribly hard to control, my Salvatore runs hot, but is set it and forget it. Very simple machine. Occasionally you could have a thermospyhons stall where the movement of water stops and the grouphead cools, in which case a split second flush is enough to get it going again.

#9: Post by **Cuprajake** » December 30th, 2022, 11:10 am

It's quite hard to stall them though isn't it

December 30th, 2022, 11:24 am

daveyb wrote:Greetings, the three things you refer to are not limited to spring levers. They actually refer to the method used of heating the hot water and delivering it to the group head.

Very true, I was just trying to understand these terms as applied to spring levers, the type I'm interested in, although they may apply to manual levers as well. And I wasn't sure that these were the only types that existed LOL!

Dippers in a non technical explanation, are where the boiler bolts directly onto the group head, making the control of water temperature all but impossible. This means you need a cooling flush. once warmed up if you draw water out the boiler has it at steam temperature and it 'fizzes'.

So, I've seen some DB levers described as having dippers, is that correct? 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?

A thermo syphon kind of sits between the boiler and group and is a way of regulating the water temperature. It is successful to a degree but you need the intervention of a pid or other electronics to accurately control it.

Understood, this was the only term that I'm very familiar, from HX machines.

Set a budget, then decide if you want a single boiler machine or a dual boiler. A dual boiler has 2 boilers, one for producing steam and one for producing water for the espresso.

Agreed. Doing that now, but I don't have a money tree out back, so I want to make sure that I get the machine features I'd like to have, for the best value AND understand how it works, which will be why I choose a specific machine.

A machine like the ACS Evo Leva is a dual boiler sprung lever machine wiht electronics to control temperature of both boilers and the group head , the latter using heat cartridges.

This thing is gorgeous AND compact... wow. Very nicely done.

Everyone will have their own favourite system of course! Personally, I would steer clear of the dipper arrangement unless you like to guess! The thermosyphon is old technology, but read as much as you can!

So very true... and that's ok with me. I'd love to hear others experiences and feedback on these machines.

Thank you daveyb for taking the time to chime in and offer your input on this, it's greatly appreciated.