PID possible for Olympia Cremina?

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sbrussell

#1: Post by sbrussell » Apr 20, 2012, 12:06 pm

We're visiting our son's family in Wawatosa WI where they just opened a great bakery. I discovered he had a 1983 Cremina, non-functioning he says, but looks to be in good condition. He offered it to me so I have a new project (He has a big Synesso in the bakery).
My question is this: if I want better temperature control is it possible to monitor and control boiler temperature with a PID ? The newer models have a pressure gauge but since pressure correlates with temperature why not a PID? Is this technically unsound or it aesthetics? And if I do use a PID where would the J or K thermocouple read the temperature from? Inside (how deep)? On the metal exterior (top, upper side, lower side?)
Russell

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Possepat

#2: Post by Possepat » Apr 20, 2012, 12:28 pm

PID'ing the Olympia Cremina is a very nice thread outlining one persons Cremina PID goal.

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TomC
Team HB

#3: Post by TomC » Apr 20, 2012, 2:06 pm

Yes, you could PID it, but if the results in the cup are consistent and fantastic, why mess with a well designed instrument?

Mine is just starting to get used after the rebuild, and it already pulls finer shots than anything I've had in cafe's in san francisco or from my pump machine.

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bostonbuzz

#4: Post by bostonbuzz » Apr 20, 2012, 2:31 pm

A ~20$ modded taylor thermometer from erics and a piece of aluminum tape will get you WAY closer to thermal consistency than a PID will.

I would love to PID my cremina, although this would only get you a short way to total temp control. The boiler only changes temp 8 degrees at the top and bottom of the cycle (affecting the brew temp. less than 8 degrees), and the bell temp is FAR FAR FAR FAR more important than the boiler temp.

I, however, would not PID my cremina if it involved a big ugly box, or anything at all protruding from the case. I will totally drill a hole in the bottom plate for a k-type or j-type thermocouple. I don't see a need to view the pid all the time or ever adjust it ever, since the group temp is how I adjust hotter or cooler temps. I also assume that we must have a vacuum breaker to have a pid, which is easy to order on the Orphan website.

If you could figure out how to do a totally reversible and non-visible PID (except for the plate hole), I would be forever in your debt.
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uscfroadie

#5: Post by uscfroadie » Apr 20, 2012, 2:50 pm

Russell,

You are confusing the benefits of a PID'd double boiler with a lever machine. Regulating the temp to within 1 degree inside a sigle boiler that is used for both steaming and pulling shots is pretty much pointless. This has been done, and the results were never spectacular. Not to mention you will have a box with the brain sitting outside the machine, which will do nothing for the cool factor.
Merle

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KurtAugust

#6: Post by KurtAugust » Apr 20, 2012, 3:03 pm

Did you read this: La Pavoni + PID = better temperature control?
I guess it is pretty similar and Jay is very happy with the result!
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vberch

#7: Post by vberch » Apr 20, 2012, 5:48 pm

Russel,

I just sent you a PM.
sbrussell wrote:We're visiting our son's family in Wawatosa WI where they just opened a great bakery. I discovered he had a 1983 Cremina, non-functioning he says, but looks to be in good condition. He offered it to me so I have a new project (He has a big Synesso in the bakery).
My question is this: if I want better temperature control is it possible to monitor and control boiler temperature with a PID ? The newer models have a pressure gauge but since pressure correlates with temperature why not a PID? Is this technically unsound or it aesthetics? And if I do use a PID where would the J or K thermocouple read the temperature from? Inside (how deep)? On the metal exterior (top, upper side, lower side?)
Russell

sbrussell

#8: Post by sbrussell » Apr 20, 2012, 6:11 pm

A ~20$ modded taylor thermometer from erics and a piece of aluminum tape will get you WAY closer to thermal consistency than a PID will.

I may see what you have in mind, but I'm not sure. Is the point that regulating the high boiler temperature is largely pointless, but that measuring the brew head temperature provides good guidance to time a shot?
I would like to get the details.
The newer Creminas have a pressure gauge which is measuring boiler pressure which correlates with boiler pressure. If boiler temperature (and hence pressure) is more or less irrelevant, what the point of a gauge?
I've never used a level machine, so my questions are based on ignorance of actual practice. But Olympia (and users who pay a lot more new machines or who pay to retrofit a pressure gauge on older models, must think the information is useful in some way--even if actually measuring the brew-head temperature is even more useful.

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RayJohns

#9: Post by RayJohns » Apr 20, 2012, 9:05 pm

KurtAugust wrote:Did you read this: La Pavoni + PID = better temperature control?
I guess it is pretty similar and Jay is very happy with the result!
Yeah, the La Pavoni is amazing now. In fact, I was just having coffee with my neighbor and he didn't even realize the machine didn't come with the PID controller - that's how factory it looks. He kept saying, "you put that in there?"

Ray

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bostonbuzz

#10: Post by bostonbuzz » Apr 21, 2012, 11:07 am

Check these two threads out to find the importance of the grouphead temperature. Olympia Cremina Temperature Study, Part 2, Olympia Cremina Temperature Study, Part 1
The newer Creminas have a pressure gauge which is measuring boiler pressure which correlates with boiler pressure. If boiler temperature (and hence pressure) is more or less irrelevant, what the point of a gauge?
The boiler pressure (and therefore temp) is not irrelevant. I always pull my shots at the bottom of the cycle, around .75 bar to keep it consistent. Consistency is the key. Higher pressures are only helpful for steaming milk. Having a PID would help me and you because you wouldn't have to fuss with what end of the cycle you were on, so you could gain that extra ~10% accuracy.

Having the boiler at .7 bar or .9 bar (the operating ends of my boiler cycle) is only a difference of about 8 degrees, and I think it has even less of a diference when it gets to the coffee. Contrast this to the grouphead temperature.

Bled of false pressure and up to temp, my grouphead is about 100 degrees Fahrenheit. I have to flush it a bunch of times to get the group to 180 where I pull my shots. If I didn't have a way to know the group temp, I might not flush enough and the temp would only be 150. (note, you can raise the temp by pumping, and not actually flushing any water as well) The shots would be awfully sour (trust me I went through years of this). After you pull a shot at that temp, the group will then be at 190 for your next shot, which will be scorched and bitter. After that, it will be at 200, and you have to cool it down again.

See where I'm going? You simply have no idea what is happening if you don't know the group temp. Notice that the exact boiler pressure is secondary to the group temp. In the above example if you pulled all the shots at the top or bottom of the cycle consistently (i.e. had a PID), it would make no difference, you would still be in the dark. Ideally, you would have a measurement of group temperature, AND a PID, but the PID wouldn't be the key to getting great shots.

Currently, I can get shots within .5 degrees Fahrenheit of what I'm shooting for with erics' taylor thermometer and pulling at the bottom of the cycle (note that I don't actually know the exact brew temp, but I know what a good shot grouphead temp is during the shot, and what a hot one is, and a cold one etc.) A pid would simply allow me to not have to "surf" my machine to pull a shot, and is therefore desirable, but not the way to shot temp stability absent a grouphead temp. measuring device.

This all being said, I know there are many (almost all) Cremina owners not using a temp strip or thermometer on the group and going by feel. After years of experience, this method may work out well, but I cannot personally recommend it, and if you're going the route of a PID, you probably want more control anyway. Lately I've been putting my hand on the group briefly, and trying to guess the temp, and I'm always 10-15 degrees off, so I'm sticking with my thermometer which is fast and accurate.
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