Olympia Cremina Temperature Study, Part 1 - Page 5

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tekomino (original poster)
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#41: Post by tekomino (original poster) »

Yes:
tekomino wrote:If you have OE temp strip then keep first bar unlit at all times before pulling the shot or shot temperature will be too hot. Even if its unlit i.e. it just went out, it is too hot and you need to cool down some more.

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erics
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#42: Post by erics »

Do these wires end in a little probe that can be taped, and if they do, can you pull them out of the hollow thermometer tube?
Yes - see below pic - how many do you want? :) - probably about $13 delivered.

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bostonbuzz
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#43: Post by bostonbuzz »

Wow, THANKS!!! This would be great, the only question is where/how to mount the display. I wonder if, tekomino, you had such an accurate reading of the bottom of the bell, if you could see if the temperature of the bell directly relates to the temperature of the shot. So that if the bell is at 165, regardless of other variables (like the time that it's been on and ambient air temp), the brew temp would be 199. An then we could get figures for 198, 202 etc (i.e. 170 bell temp. = 202 brew temp)! This would really be some priceless info.

Erics, you will hear from me shortly about getting one of those disassembled thermometers. Does the conical back plate have to go back on? Otherwise, I could possible use some sort of adhesive to stick the flat bit onto the front of my machine.
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erics
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#44: Post by erics »

Does the conical back plate have to go back on?
No, but I would probably come up with some money losing :) scheme for this "one-off". To me, this is simply an inexpensive adventure for both of us.
Skål,

Eric S.
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E-mail: erics at rcn dot com

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tekomino (original poster)
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#45: Post by tekomino (original poster) »

The thermometer is interesting and I thought about it, problem is mounting it and I am not sure that having exact temperature would add value.

I think you'll have lot of trouble hitting the exact temperatures if that is what you are after. You could get into the range but getting exact temperatures will be very hard. That's why I like temp strip. It provides you with range and not exact values and thus by removing the exactness simplifies the process...

In any case I'd love to read about your findings :D

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erics
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#46: Post by erics »

I am not sure that having exact temperature would add value.
I certainly do not disagree. However, given the relative low cost and the non-permanent nature of this add-on, it fits like a glove into the adventure category.
Skål,

Eric S.
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tekomino (original poster)
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#47: Post by tekomino (original poster) »

erics wrote:However, given the relative low cost and the non-permanent nature of this add-on, it fits like a glove into the adventure category.
100% agree. I think by the end of this adventure we should know much more about Cremina temperature management and end up having some good tools to help us along the way both of which was my goal.

Eric, any ideas on how to attach the thermocouple to group head in non-permanent way?

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erics
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#48: Post by erics »

The 50K ohm negative temperature coefficient (NTC) thermistor is small - see pic below.



I would mount it on the rear of the group with a 1/4" x 1/4" piece of the high quality, aluminized ducting tape (not your normal duct tape) which I would be more than happy to send along.
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Eric S.
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E-mail: erics at rcn dot com

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peacecup
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#49: Post by peacecup »

A couple problems in precise replication of brew temperture are variation in boiler temperature and variation in water dwell time in the goup. Even if one were to fill the group at exactly the same time (e.g. when the pstat kicks on or off) the temperature in the boiler is likely to vary by a couple of degrees. And rememeber, this water needs to cool A LOT before its ready to brew. This is done in the group, and dwell time and group temp interact to do this. Simply, the longer in the group the cooler the water, but the speed at which it cools will vary based on the group temperature. So I agree with Dennis that a few-degree precision is the best to be hoped for.

It's still very information though, and something I've been waiting for for a long time. Fortunately, lever espresso is so good that a few degrees give or take doesn't matter that much.

Just for fun I've been leaving my Export run for hours the past few days, and just locking in a room-temp PF, waiting for it to warm, then pulling the shot. They taste great.
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bostonbuzz
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#50: Post by bostonbuzz »

I agree it would be very difficult to get a precise temperature on the group, bu I can imagine getting quite close by using "1/2" or "1/4" flushes to slowly raise the temperature and noting the lag time etc. Also, the boiler state would throw off the speed of the temperature change (I think it's only an 8F degree change in boiler water between .75 and .9 bars). The different rate of change could be negated, however, by a very slow flush, or simply by flushing at the same point in the heating cycle, like right when the light goes off.

Since we know so little about how easily the group makes small temperature changes, this technique is very much open to experimentation. Assuming a +/- 5 degree accuracy in getting the group to a specific temp, I'm curious how the brew temp relates. It could be a narrow band, or most likely quite wide: i.e. 155/165 group= 198/199 brew or something like that.

Given that I don't have a way to measure brew temp, and that I'm still struggling with my seals creating some channeling, I don't think my Cremina is the best candidate :oops: . This could be a lever machine breakthrough! However, as many here have said, it may not be necessarily needed (I need it though :wink: )
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