How to predict LP Europiccola brewing temperature from grouphead temp ?

[arcticroaster1]

Hi all,

I wonder if there are any resources about how to predict LP Europiccola brewing temperature from grouphead temp ?

I mean, it's easy finding of stories how badly the thing behaves, how it heats up, how you always shoot into the dark etc, but has anybody ever measured this machine in more detail and come up with some grouphead "temp surfing" type of rules ?

What I mean is correlating grouphead temperatures (at some tbd location) to the brewing water temperatures in the PF you would then subsequently get during either the initial warming-up phase or after deliberate cooling of the grouphead in case of multiple shots ?

For any given selected boiler temp and water level there must be a certain grouphead temp during the heat-up phase, at which the brewing water would just end up to be at appr. 90 deg and it would be nice to know at which exactly so speed up the dial-in times ?

Any pointers appreciated,

Cheers Peter

[timo888]

Hi all,

I wonder if there are any resources about how to predict LP Europiccola brewing temperature from grouphead temp ?
...
For any given selected boiler temp and water level there must be a certain grouphead temp during the heat-up phase, at which the brewing water would just end up to be at appr. 90 deg and it would be nice to know at which exactly so speed up the dial-in times ?
...

It is not as simple as a direct correlation of grouphead temperature to the temperature of the brew-water hitting the puck. You would also have to know the temperature of the water as it leaves the boiler, and that temperature can vary. Think of the group as an input-output function: even if you could determine the group's degree of heat saturation by taking a single temperature-index measurement at a location to-be-determined, and then arrive at a factor representing the group's remaining heat-sinking capacity, you would still need to know the input water temperature before you could determine the output water temperature. How are you going to "select" the boiler water temperature on a Europiccola?

Regards
Timo

[hbuchtel]

It is not as simple as a direct correlation of grouphead temperature to the temperature of the brew-water hitting the puck. You would also have to know the temperature of the water as it leaves the boiler, ( . . .) you would still need to know the input water temperature before you could determine the output water temperature.

Regards
Timo

No problem, just look at the pressure gauge! (does the Europiccola have a pressure gauge?) Wait, what do you mean by "as it leaves the boiler" ? Knowing boiler temp and 'grouphead temp' should be enough, I think.

The problem would be finding the most representative place to measure grouphead temperature... it's a cool idea!

Remember that as the machine is warming up the pressure building up will slowly push water out of the boiler all the way to the 'valve' (also known as piston!), so the water for your first shot has already been outside of the boiler for a couple minutes...

Peter, why do you think the water level would be important?

Henry

EDIT: perhaps Boiler Temp + temp of water in the inlet tube just before the piston?

[espressme]

Hi Henry,

No problem, just look at the pressure gauge! (does the Europiccola have a pressure gauge?)

snip
Most of the early LaPav had no pressure gauges. IIRC I think the Professional was the first home model to do so. Here is one of many threads on the subject. And, many were made without pressurestats.
http://www.home-barista.com/forums/post20482.html#20482
Just put one on my old 8 cup Europiccola with a fancier adapter.
There is a big difference and with the hi/low element switches I can call shot and head temp with flushes. It is nice to steam like a banshee and make more than one or two cups of espresso to a reasonable level of quality. Maybe 3 to 5 before a boiler refill is necessary.

Wait, what do you mean by "as it leaves the boiler" ? Knowing boiler temp and 'grouphead temp' should be enough, I think.
snip

IMO The problem as I see it it that the boiler brass can transfer heat to the group very quickly because it is bolted directly to it. So, if the boiler temp is high for steaming, then about two shots will overheat the group. I believe that controlled boiler temp is the key and all other variables can work around that. Boiler temp soon = group temp.

Henry EDIT: perhaps Boiler Temp + temp of water in the inlet tube just before the piston?

Sincerely
Richard

[timo888]

No problem, just look at the pressure gauge! (does the Europiccola have a pressure gauge?) Wait, what do you mean by "as it leaves the boiler" ? Knowing boiler temp and 'grouphead temp' should be enough, I think.

The problem would be finding the most representative place to measure grouphead temperature... it's a cool idea!

Remember that as the machine is warming up the pressure building up will slowly push water out of the boiler all the way to the 'valve' (also known as piston!), so the water for your first shot has already been outside of the boiler for a couple minutes...

Peter, why do you think the water level would be important?

Henry

EDIT: perhaps Boiler Temp + temp of water in the inlet tube just before the piston?

As it leaves the boiler, as it leaves a tube leading from the boiler... the principle remains the same. You cannot determine the temperature of the water leaving the group and hitting the puck if all you know is how heat-saturated the group is before the water reaches it. If the machine had a pressure gauge (Europiccolas don't) you could derive the needed input value for the function.

Regards
Timo

[arcticroaster1]

It is not as simple as a direct correlation of grouphead temperature to the temperature of the brew-water hitting the puck. You would also have to know the temperature of the water as it leaves the boiler, and that temperature can vary. Think of the group as an input-output function: even if you could determine the group's degree of heat saturation by taking a single temperature-index measurement at a location to-be-determined, and then arrive at a factor representing the group's remaining heat-sinking capacity, you would still need to know the input water temperature before you could determine the output water temperature. How are you going to "select" the boiler water temperature on a Europiccola?

Regards
Timo

Hi Timo,

yes certainly. What I had in mind is to start the shot always at a certain boiler water temp + then this correctly matched grouphead temp. The pressurestat on my machine is going on/off in quite short intervals, so could you use here boiler temp surfing like the guys on Silvias, ie you count x seconds after the heater goes off and that gives always then a fixed temp (may depend on water levels?)

In the meantime the grouphead (GH) will heat up all the time and could it be possible then to obtain a "matching" boiler+grouphead temp ?

I am in process of ordering 6 surface and couple of wire k-type thermocouples + 4 channel datalogging and 2-channel non logging thermometers which should allow one to investigate in detail if this could fly.

First thing would be to measure the boiler temp "roller-coaster" (due to pressurestat), perhaps at a location near the pipe which feeds the GH and additionally temps on some GH locations (to get a feel of the GH temp spread) and also the slope of the GH temp rise.

Then one would start trying to find the "matching" boiler+grouphead temps by additionally measuring the resulting brewing temp (another TC going into PF). There may be also several solutions of this (cooler boiler water, hotter GH or vice versa).

Then to stabilize the Europiccocla in case of multiple shots I was thinking to cool the GH down and then have its temp rise again until it matches the "surfed" boiler temp again.

I was just wondering if devising such scheme would stand a chance of working and saving myself some troubles if you can see right away it won't

Unfortunately there are delays with my TC orders, so it will take a while before I can report some progress back here.

BR Peter

[arcticroaster1]

1) No problem, just look at the pressure gauge! (does the Europiccola have a pressure gauge?) Wait, what do you mean by "as it leaves the boiler" ? Knowing boiler temp and 'grouphead temp' should be enough, I think.

2) The problem would be finding the most representative place to measure grouphead temperature... it's a cool idea!

3) Remember that as the machine is warming up the pressure building up will slowly push water out of the boiler all the way to the 'valve' (also known as piston!), so the water for your first shot has already been outside of the boiler for a couple minutes...

4) Peter, why do you think the water level would be important?

Hi Henry,

thanks for reply. Couple of thoughts to your points (I numbered them):

1) No, Europiccola doesnt have pressure gauge, so I thought to use a surface-mount thermocouple on the boiler, perhaps on the level of the GH water pipe inlet. If my understanding is correct, then measuring either pressure or temp is equivalent, as you can determine one from the other via the steam-tables. What I am not sure is how accurate & fast these outside boiler temp measurements will be

2) yes, I would expect a complicated temp distribution on the GH, actually you can feel it already during warmup. The heat comes via the "bridge" from the boiler and you get quite large differences. I was thinking to put couple of surface-mount thermocouples on the GH to get a better picture and check possibility for some "average" temp. And this GH temp distribution may look quite different at initial warmup compared to warmup after cooling (after multiple shots). So, this may be a long shot...

3) hmm, that's interesting (complicating matters even further...), I didnt know that. What happens if you push the piston up for the 1st shot, I mean you must be displacing then parts of this water back into the boiler again (through these large gaps on top of the sleeve) ?

4) I was thinkig that the rate of heat tarnsfer to the GH may depend on the boiler water level (better heat conduction near the GH "bridge") and therefore may play some role. I am not sure about it, have to measure it.

BR Peter

[arcticroaster1]

I believe that controlled boiler temp is the key and all other variables can work around that. Boiler temp soon = group temp.

Hi Richard,

but isnt the problem here, that the boiler temp will always be > 100 C (due to the required presssure for the feedwater) and group head (GH) temp must cool the water, so has (on average) to be less, however, keeps rising towards near the boiler temp (at least near the connecting bridge).

So even we control the boiler temp accurately with, say, some PID or whatever, we still got that moving target of (rising) GH temp which complicates everything.

I dont know how the HX Gaggia Achille has solved this problem (or has it?), it seems to require cooling shots as well to keep the GH at some defined temp relative to the water temp coming out of the HX ?

BR Peter

[arcticroaster1]

If the machine had a pressure gauge (Europiccolas don't) you could derive the needed input value for the function.

Hi Timo again,
so this sounds to me then that perhaps this would be worth investigating a bit further (in my case using TC instead of pressure gauge for the boiler temps as it would be more straightforward to implement).

OK, I keep in touch then on this subject once I got my setup operational.

BR Peter

[Ritske]

Espressme (Richard),

You mention that you've just added a gauge to your two-switch Europiccola. I've just done the same for my millenium model, and am experimenting with different boiler-pressures by switching the machine off, waiting for the pressure to drop to a certain pressure and then pulling a shot (single pulls). I've done some measurements of the brew water temperature as well by using a digital thermometer and a styrofoam cup, and it seems that pulling at a lower pressure definitely influences the brew water. Shots pulled at 0.9 bar are generally appear to be 1-2 degrees higher in temperature then shots pulled at 0.75 bar. At what pressure do you get good results?

Ritske

[ulrikmo]

HI Guys

Interesting post, have never seen anyone playing with the idea of inserting TC at their Pavonis!

Have owned quite a few pavonis, first a europiccola, then a professional and now a newly restored 60ies model ( see the thread waking up a vintage pavoni in this forum).
This oldie doesn't feature a pressuregauge, but I am planning on installing one, ordered the stuff needed from expressoxxl. de, this model has however the advantage of a minimo-massimo switch, which I believe with the information from a pressure-gauge would allow you, both to keep it at low pressure with just the minimo switch on ( meaning lower temp) and switching it to massimo for steaming. It's how I'm running it now just using experience from earlier shots.
The only limit for the temp-build up at the massimo is the pressure-relief valve, I believe, judging the hiss which can grow quite aggressive that it builds up to almost 1,7, making steaming on this machine a lot better, than on the pavonis I've owned before. There is however a great risk of getting burnt shots, if you're not catious about pulling you shot quickly, and a higher tendendy of overheating Grouphead as well, when the massimo mode is selected. But the two switch model, should theoretically allow you to have temperatures of maybe 105 degrees in boiler (probably dropping to 95 at puck) and to kick it up to 125-130 for steaming. This could enable you for more shots before overheating became a problem.

Don't know why they abandoned the two-switch.. Any clues?

Cheers And good luck with the project!
Ulrikmo

PS: Outside boilertemp in pavonis are nearly evquivalent to inside, since there is no insulation of boiler and the brass is an effective heat-transmitter, so think you will get quite exact measures on the outside of the boiler, it will probably be more of a challenge with the grouphead vs puck-temp, maybe the styrofoam method would do?

[timo888]

Hi Timo again,
so this sounds to me then that perhaps this would be worth investigating a bit further (in my case using TC instead of pressure gauge for the boiler temps as it would be more straightforward to implement).

OK, I keep in touch then on this subject once I got my setup operational.

BR Peter

The usefulness of the boiler outside surface temperature as an index to water temperature will depend on the extent of the time lag. How long does it take for the surface to reflect a change in the internal water temperature? To estimate this lag, drop the boiler pressure by letting out a lot of steam, and note how long it takes for the surface temperature of the boiler to reflect a change--you won't know exactly how much change occurred, and so without a pressure gauge and steam tables, you may be flying by the seat of your pants, despite the thermocouples.
Regards
Timo

[hbuchtel]

A few more thoughts about the temp measurement-

Some (how much?) of the water for your shot will have been sitting in the tube in the group neck, some of it will come from the portion of the tube reaching into the boiler, and (maybe) some of it will actually come from inside the boiler.

With the piston down (valve closed) the group neck will be drawing heat from the water in the tube, when you raise the piston/lever water will rush into the piston chamber and the group head will absorb some of the water's heat.

Peter, I think with the piston down the body of the piston blocks the end of the inlet tube. Water never goes above the piston. I think the Cremina piston is 'saturated' ie water fills the area above the piston and is forced out as the piston is raised.

Onward and upward!

Henry