La Pavoni Europiccola 2021 - Bypassing the pressurestat

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soer9459

#1: Post by soer9459 »

Hi all

Id like to do an experiment with my La Pavoni which requires me to disconnect the p stat entirely.

I saw this video: http://www.youtube.com/watch?v=kKM8kgyqUQY
In it, he has two configurations:
1. A setup with 2 separate p stats set differently
2. A schematic where the dual switch can select either going through, or entirely bypassing the p-stat. (which I believe is how the old EPs worked?)

Now, I currently have a single switch europiccola, but want to try bypassing the p stat, and simply riding the on/off switch (which I'm doing currently anyway).

The schematic for my machine is shown in this image. I just don't know how exactly to bypass it, as I know absolutely zero about electrical circuits.



Bonus question: Is there any resource that goes through explaining how the machine actually works, and what the different parts are?


Thank you

baldheadracing
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#2: Post by baldheadracing »

soer9459 wrote:Hi all

Id like to do an experiment with my La Pavoni which requires me to disconnect the p stat entirely.

I saw this video: video
In it, he has two configurations:
1. A setup with 2 separate p stats set differently
2. A schematic where the dual switch can select either going through, or entirely bypassing the p-stat. (which I believe is how the old EPs worked?)

Now, I currently have a single switch europiccola, but want to try bypassing the p stat, and simply riding the on/off switch (which I'm doing currently anyway).

The schematic for my machine is shown in this image. I just don't know how exactly to bypass it, as I know absolutely zero about electrical circuits.
image


Bonus question: Is there any resource that goes through explaining how the machine actually works, and what the different parts are?


Thank you
Sorry, I don't mean to offend, but "I know absolutely zero about electrical circuits." means that I am very uncomfortable.

To be blunt, just bypassing the pressurestat is not a good thing and would only be needed if you want to have the boiler pressure higher than what the pressurestat is set at - in which case the thing to do is adjust the pressurestat. However, the safe maximum pressurestat setting for a Pavoni boiler is about 1.1bar, and I can't imagine needing a higher pressure than that. (Yes, I've seen 1.5 bar used. No comment.)

One can wire in a second circuit that cuts in at a lower pressure. I used a PID controller to set a pressure lower than the pressurestat setting for experiments. Bong used two pressurestats in the video, and switches between the two. There is always one of the pressurestats controlling the maximum possible boiler pressure. He gave the wiring diagram in the video and, again, if you can't read that wiring diagram, then I am uncomfortable.

(I think that the first diagram is unsound, and note Bong doesn't recommend it. If you don't understand how dangerous it would be, then ...)

Note the two switch Pavoni's that do not have a pressurestat have a different mechanical safety valve setup which you would have to retrofit to your pressurestat machine, along with changing to the two element boiler base - depending on what you want to do.

What are you trying to accomplish? I honestly can't think of any situation where removing the pressurestat from the control circuit makes sense.

For the bonus question on how the machine works, have a look at John Michael Hauck's channel: http://www.youtube.com/c/JohnMichaelHauck
- My espresso: Swirled, not stirred. My pourover: Stirred, not swirled.
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soer9459 (original poster)

#3: Post by soer9459 (original poster) »

No offence taken :) I realise I'm a dummy

I'm contemplating installing a PID or doing the second p stat config somewhere down the line, because the steam pressure at 0.7-0.8 bar simply isn't enough.

I currently have the pressure stat maxed at 1.2 bar for steaming, and I simply turn the machine on/off for espresso making, to keep the pressure at about 0.8 bar, before letting it heat all the way up to 1.2 for steaming. Works ok, but is kinda annoying

From what I've been able to see online, people are running their EPs at way higher pressures (I saw one example of someone running at 2 bar), but I was only ever going to run it at 1.5 to see the steam improvement at that pressure. I believe the safety valve opens at about that pressure anyway

I realise that I'll never achieve pro-level steaming performance, but even at 1.2 it seems weak to me. I'll also have some other things in the mail to experiment, like different smaller jugs etc.

baldheadracing
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#4: Post by baldheadracing »

Okay, that makes good sense :D.

Switching to a one-hole steam tip seems to help (with the one hole at the "right" size). That makes steaming better, but slower. There's only so much steaming time available given the Europiccola's boiler size. :oops: One thing that you can do is keep the water level in the boiler fairly low - but not too low! That gives more internal volume for the steam to be in, and thus, more steam immediately available - but, regardless, once the boiler pressure falls, you run out of steam. :oops:

I only pull one (split) double out of my Europiccola so I run the boiler at 1.1bar and the water level about 4cm from the bottom of the sight glass to get things up to temperature faster. That means I have to pull that shot within a relatively small window of time before my gen1 group gets too hot ... but I can go from turning the machine on to drinking/serving two Italian-sized cappuccinos within ten minutes.

The other thing people do is add a heat break between the group and the boiler, like a Teflon gasket. I can't fit one on my gen1, but you might want to consider something like this: http://www.youtube.com/watch?v=Ch3FZgOLIno
- My espresso: Swirled, not stirred. My pourover: Stirred, not swirled.

jpender

#5: Post by jpender »

baldheadracing wrote:One thing that you can do is keep the water level in the boiler fairly low - but not too low! That gives more internal volume for the steam to be in, and thus, more steam immediately available...
Does that really work?

It's not like you have a balloon full of steam. Any steam that comes out has to be replaced by new steam and that takes a certain amount of energy, which will cool the water down. For a given amount of steam a smaller volume of water will cool down more than a larger volume.

At the same time, the heating element can heat up a smaller volume of water more quickly than a larger volume. So perhaps you're right... but for a different reason?

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Jeff
Team HB

#6: Post by Jeff »

In short, a tiny boiler and a small heating element isn't going to be a steaming monster.

Your short-term "power" will be limited by the volume of the boiler. Your long-term power by the power into the element. Neither are "big" on a lightweight, kitchen-table unit.

A steam tip with the "right" size hole may help in matching what it available from the unit effectively into foam in your jug. That's something I'd try myself.

I'd recommend reading carefully about concerns around the use of heat breaks on La Pavoni units. I've read enough to be concerned about failure modes that could involve some pretty nasty boiling-water burns. It comes down to a personal risk/reward benefit, but at least make it an informed one. I'm not really confident that a heat break would significantly improve the steaming capabilities.

Increasing the pressure is a really bad idea. If you're lucky, all you'll get is impaled with sharp pieces of metal. Less lucky and you'll have nasty boiling-water burns over a significant portion of your body. It's not like accidentally waving your finger through the steam wand or over a pot of boiling water, clothing does a great job of holding that scalding water against your skin.

redpig
Supporter ❤

#7: Post by redpig »

Fwiw, I added a "turbo" switch to a la pav I had. I don't recommend doing anything that makes you uncomfortable - 120v is dangerous!! I just traced the wire from the element to the pstat and forked it and forked the wire leading on, and put an appropriately rated switch.

Unfortunately, I can't find a wiring picture :/

I just added the white button (from a different similarly aged machine). I kept it idling at brew friendly temps then held "turbo" to heat for steam.
LMWDP #411

baldheadracing
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#8: Post by baldheadracing »

jpender wrote:Does that really work?
:oops: Compare 200ml of steam vs. 500ml of steam, both at the same pressure. To make the math much simpler, assume that there is no air nor water in the boiler, and forget about the element. That means there's a 200ml vessel and a 500ml vessel. The outlet is severely restricted relative to the available steam, and, as the pressure is the same, the mass of steam moved over time through the outlet is the same. Which vessel will send more steam out as the vessel's pressure falls to atmospheric?
:oops:
Jeff wrote:... I'd recommend reading carefully about concerns around the use of heat breaks on La Pavoni units. I've read enough to be concerned about failure modes that could involve some pretty nasty boiling-water burns. It comes down to a personal risk/reward benefit, but at least make it an informed one. I'm not really confident that a heat break would significantly improve the steaming capabilities. ...
A heat break gasket can enable more steam as it allows the boiler pressure to be higher for a given group idle temperature, i.e., a greater temperature differential between the group and the boiler. Note this is for gen 1's and post-milleniums, which are conventional sleeved-group dipper designs. Gen 2's are a different story.

I did not recommend the rather thick Bong isolator. Early ones had some issues with deformation, but the manufacturer did change the material and replace the old isolators. However, I have neither seen nor used one. I linked to a video of a 2mm thick PTFE gasket that comes in a kit with 2mm longer bolts which is made by the La Pavoni distributor for Taiwan, a.k.a. BPlus. BPlus have had a strong relationship with the La Pavoni factory, although I don't know about now since SMEG bought La Pavoni. Parts that BPlus have developed have become available as La Pavoni factory parts, albeit not the PTFE gasket. Perhaps mistakenly, this gives me confidence to link that particular product, as does the quality of other BPlus parts that I have purchased. However, they do have a warning on their website: A kind of Experimental products. It has not been verified for long-term durability.

I have used a 6.4mm thick Teflon heat break on my MCaL. (Teflon with glass fibre to help counteract cold flow.) I wouldn't use one that thick on a Pavoni as the Pavoni only has two group mounting bolts arranged horizontally instead of the four bolts in the MCaL. The break allowed the MCaL to be walk-up-and-pull all day long, albeit at the cost of a long warm-up time. The long warm-up time is why I removed the heat break after six years of regular use.
- My espresso: Swirled, not stirred. My pourover: Stirred, not swirled.

LObin

#9: Post by LObin »

I've done it on my Professional.
I absolutely love it!

Here's a picture of the wiring on a millennium LP:



Here's my machine in action. I usually wait till the boiler hits 1.5 bar and start steaming. I'm currently using a 1.2mm single hole steam tip so steaming time can be improved with the stock 3 hole tip. I just LOVE the results with that single hole tip.
* My wife has left the switch on II twice already. Both times, the safety thermostat tripped around 2-2.5 bar. I'm still working on getting a spring that'll open the pressure relief valve before that happens.

Cheers!
LMWDP #592

jpender

#10: Post by jpender »

baldheadracing wrote:Compare 200ml of steam vs. 500ml of steam, both at the same pressure. To make the math much simpler, assume that there is no air nor water in the boiler, and forget about the element. That means there's a 200ml vessel and a 500ml vessel. The outlet is severely restricted relative to the available steam, and, as the pressure is the same, the mass of steam moved over time through the outlet is the same. Which vessel will send more steam out as the vessel's pressure falls to atmospheric?
When I asked "Does that really work?" I meant have you tried it?

Your simpler example is too simplified. Sure, the bigger one will expel more steam. To first approximation a vessel with steam at 1 bar gauge would expel half the mass of steam. Steam at that pressure and saturation temperature is roughly 1g/L density so about 0.25g of steam for the bigger vessel and 0.10g of steam for the smaller one.

Consider an alternative example: Two 500ml vessels, the first filled with steam at 1 bar gauge, the second with 200ml of steam and 300ml of 120°C water. The first vessel will still emit about 0.25g before it peters out. The second one will emit about 10g of steam.