Salvatore Lever vs Londinium - Dipper vs Thermosiphon

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CoffeeMan9000
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#1: Post by CoffeeMan9000 »

As I read and learn more, and narrow the search criteria, I came across a thread on the Londinium forum where Reiss was rather dismissive of the Salvatore spring lever, because it is a dipper. He claimed it would overheat. The machines use the same (other than this feature) group head.

I am hoping to gather insight into the veracity of the Reiss claim and to assist in choosing.

Thanks

John

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another_jim
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#2: Post by another_jim »

CoffeeMan9000 wrote:Reiss was rather dismissive
It's one of his character traits
the Salvatore spring lever, because it is a dipper ... would overheat.
A dipper machine draws hot water from the boiler, as for instance, the Londinium does. The Londnium has a little extra tubing on its dipper, so it's a dipper with a pike and half twist.

Dipper machines have been around since 1948; they don't overheat if they can sink enough heat to the air. This is very simply accomplished by making the group's thermal connection to the boiler slightly smaller than on an HX group, so it idles at a lower temperature. Reiss's curlicue dipper is another way of accomplishing the same effect.

HX machines fill the group at line pressure, around 3 bar, whereas dippers fill it at 1 bar. This changes how far the group fills. This in turn affects both the thermal characteristics (more water); and the pressure profile (the spring pressures the shot through a slightly more compressed range). This difference does not matter to the Londinium since like all dippers it fills to 1 bar boiler pressure.

Finally, using a thermosyphon rather than a direct flange connection to the boiler for any group, lever or pump, requires a lot more tuning and a lot less blogging than Reiss originally anticipated.
Jim Schulman

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nickw
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#3: Post by nickw »

There has been a lot written on dippers vs thermosiphons. Both are good and each require a little knowledge of how they are made/designed to get the best out of them. Personally for home use I like a good thermosyphon design.

In a nutshell:

Commercial dippers group heating and water temp:
With a dipper, the group is heated via thermal transfer from being bolted to the boiler. Often the group idles a little cold, and requires a shot or two to reach ideal temp, as most groups are tuned for cafe's and more continuous use. Water for the shot comes from the boiler via the dipper (thus it's name), and is superheated* to some degree based on boiler pressure/temp.
*Note: The newer Bosco's adjust for the super heated water with a little tank to cool the water before it hits. A nice touch. I believe they are the only dippers to do this.

Thermosyphons heating and water temp:
A thermosyphon is different in that the group is heated by circulating hot water from the boiler (via thermosyphon). When pulling a shot, water is feed to the group via the TS, so it first takes the "colder" water from the TS first before the superheated water form the boiler. They often requirer a short flush after each shot to restart the TS, which I do anyways to clear the group screen (and many dipper owners do as well to clear the screen).

For group heating, both designs require tuning:
- With a dipper: Since the group is bolted to the boiler for heating, it's a balancing between heat transferred at idle temp (so distance), vs ability to cool between shots. The hotter the group idles, the longer time needed between shots. Thus most are tuned to cafe and continuous use.
- Thermosyphon: Since the group is heated via the TS, it requires tuning of the TS to maintain proper group heating. To ensure TS restarts it requires a flush.

For cooling and continuous use:
During continuous use both require thermal mass and natural heat dissipation from the group for cooling and will be similar.

If shots are longer than 3-4 minutes apart, the TS should be flushed to ensures the TS will restart (often will restart without flush). But imho both groups should be flushed after shots anyways to keep the shower screen clear. In heavy cafe use both groups are pulling shots every 2-3minutes, so if you're to busy to flush, the TS will still be fine since it's exhausting the heat from previous shot.

To recap, both are good. Each as it's quirks.
In a home environment I like the TS. It's pretty much walk up and pull.
In a cafe, I could go either way, but would still prefer a TS (as to not deal with cool groups).

Final note:
Most levers cousins in some way, shape or form. Many share the same group, but configured differently (Bosco, Kees, QM, Salvatore, Londinium). I would still take any of the levers mentioned over almost any pump machine.

Séb
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#4: Post by Séb »

There are two Salvatore spring lever machine. The Compact spring lever is not a dipper, it use a thermosyphon just like the L1. I believe Reiss was comparing with the full size Salvatore spring lever machine which is probably a dipper (i don't know).

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JohnB.
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#5: Post by JohnB. »

nickw wrote: Commercial dippers group heating and water temp:
With a dipper, the group is heated via thermal transfer from being bolted to the boiler. Often the group idles a little cold, and requires a shot or two to reach ideal temp, as most groups are tuned for cafe's and more continuous use. Water for the shot comes from the boiler via the dipper (thus it's name), and is superheated* to some degree based on boiler pressure/temp.


*Note: The newer Bosco's adjust for the super heated water with a little tank to cool the water before it hits. A nice touch. I believe they are the only dippers to do this.
Are any of the currently available levers that use commercial groups true dippers? A Cremina is a true dipper as the group is bolted directly to the boiler. The Bosco, Izzo Leva, Pompei (if it's the same as the Leva) all mount the group to the front upright frame & connect the group to the boiler with a large tube. Couldn't find any photos of the full size Salvatore lever's boiler arrangement. My understanding is that this makes them a hybrid dipper design. This design seems to be far less prone to overheating then a true dipper design.

The reservoir on the Bosco stores the water for the next shot allowing it to cool some as opposed to pulling the shot water directly from the boiler. Once fully warmed up a 2 second flush before shot prep is all that's required with my 1.25b p'stat setting to get the group up to a 201°F peak shot temp after a long idle period. If you were aiming for a cooler shot temp you'd use a shorter flush or no flush at all.
LMWDP 267

HBfencing
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#6: Post by HBfencing »

CoffeeMan9000 wrote:As I read and learn more, and narrow the search criteria, I cam across a thread on the Londinium form where Reiss was rather dismissive of the Salvatore spring lever, because it is a dipper. He claimed it would overheat. The machines use the same (other than this feature) group head.

I am hoping to gather insight into the veracity of the Reiss claim and to assist in choosing.

Thanks

John
John can you provide a link where Reiss stated that? In my correspondence with Reiss never did he attempt to sway me to purchase his machine and I did tell him I was considering the Compact Spring Lever. As far as why I chose to go with Salvatore it came down to a slightly shorter depth on the counter, the option to have the case powder coated and in the color of my choosing, a different variation of the group 2 springs versus 1 spring with the Londinium and the hand made intangible factor. I'm sure you can't go wrong with either machine. Boils down to personal preference. The Compact Spring Lever is a thermosyphon design. When I get my machine I will post pics here as well as provide observations. I don't have any fancy equipment to measure thermal observations but I have been corresponding with Erics and if he makes it up to my neck of the woods perhaps he can take some readings.

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Bob_McBob
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#7: Post by Bob_McBob »

http://londiniumespresso.com/forum/pre- ... lever#3079
Reiss Gunson wrote: one group is dipper fed

one group is thermosiphon fed

one of these designs over heats

one doesn't
Chris

HBfencing
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#8: Post by HBfencing »

Thanks Bob I missed that. Time to take out my distance contacts when searching.

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hankua
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#9: Post by hankua »

Here's the top and bottom Salvatore thermosyphon tubes; group left, boiler right. Brass block feed the lower port on the group. I've got bare K type thermocouples running to a Fluke 54II and can watch the hot vs cold side. If it's not a thermosyphon, then how does it work?


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pizzaman383
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#10: Post by pizzaman383 »

hankua wrote:Here's the top and bottom Salvatore thermosyphon tubes; group left, boiler right. Brass block feed the lower port on the group. I've got bare K type thermocouples running to a Fluke 54II and can watch the hot vs cold side. If it's not a thermosyphon, then how does it work?
That does look a lot like a thermosyphon would look (it looks like a duck). Do you see a temperature differential between the two tubes (it quacks like a duck)?
Curtis
LMWDP #551
“Taste every shot before adding milk!”

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