Olympia Cremina Temperature Study Part 3 - Page 2

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SpaceTime

#11: Post by SpaceTime »

Do you have a heat break installed between the group and boiler? (aka "Teflon" type gasket available as OEM replacement seal, or similar one supplied as an aftermarket material). The stock part when your Cremina was made is the group to boiler o-ring, of course, but many have either rebuilt / replaced their gaskets with the newer OEM seals, others have not. Others still have used aftermarket solutions for the same effect.... (like ULTEM, Virgin Teflon, etc).

The reason I ask is I have two Creminas currently (an '83 and an '89) that were both rebuilt from the ground up by me, with all new seals and gaskets. One has the OE full gasket kit, and one has the OEM full gasket kit from Cerini's with the heat break. My "testing" has found completely different characteristics in how hot the group gets on start up, how many "pulls" it takes to bring the group up to temperature, how well the group stays at a consistent temperature as the machine sits idling, and how fast the group cools down - and how easily you can cool it down with a cold portafilter reinserted.

I also ask because, of course, it will have a different result / curve on your tests, and it would be interesting to compare the results side by side. My "testing" is only done with a Thermapen and temperature strips, and I am not logging any data, nothing scientific, but the differences are noticeable.

I find myself starting to opt for the Cremina with the heat break, as I find it more "manageable" from the standpoint of a more easily controlled warmup, and cool down. The heat break minimizes the effect of direct boiler contact with the group obviously.

Anyway, just curious what you had installed, and if you were planning on doing any comparative analysis.... it would be interesting to see the effect of this difference on your results.... :wink:
If I could just like crappy coffee again, it would sure save a lot of time and money!

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naked-portafilter (original poster)

#12: Post by naked-portafilter (original poster) »

Hi Tim,

Thankx for your remarks/questions! I replaced all gaskets/seals except the one between the group and boiler. No question I'm going to do it soon. Cooling down the group just to lock a cold portafilter at leat 9 (!!!) times is more than enough. I know there are other ways but I was curious (see below).



But actually I have another question/problem. The Cremina idles now between 260 and 270 Fahrenheit (made no changes) reasonably higher as at the first measure (230-240). Something's wrong. Don't get it.... But no time to play with it now.

EDIT: !!!THE HIGH TEMPERATURE MEASURES WERE CAUSED BY A FAULTY THERMOCOUPLE!!! 04.04.2014

I'll buy the oem thermal break gasket for sure a make new measures. It'll take time though :-).

SpaceTime

#13: Post by SpaceTime »

It would be interesting to see....

BTW, this is outstanding to see these tests, as a Cremina owner more data is helpful in making the best possible shot!!

One note - thank you for bumping up the font size on the graphs, I was having trouble reading the text... was going to note that, but it seems you caught it... still having a wee bit of trouble on the first couple of graphs. Probably just my old eyes.... 8)
If I could just like crappy coffee again, it would sure save a lot of time and money!

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drgary
Team HB

#14: Post by drgary »

If your Cremina is suddenly idling at high temp it's probably because your PSTAT has gotten clogged with scale. You may have seen the rpavlis recommendation to descale that with vinegar instead of citric acid to avoid clogging it with a different precipitant than what's already there.

BTW we've all seen the bell curve but now you've mastered the umbrella curve. :D
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!

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naked-portafilter (original poster)

#15: Post by naked-portafilter (original poster) »

Hi Gary,

Thanks for your hint. I haven't read rpavlis recommendations regarding this. I will look into it asap and make a new measure. Now it idles again between 230-239 Fahrenheit :-). I hope I can descale it at the week end.

Kind Regards

Gabor

SpaceTime

#16: Post by SpaceTime »

Hi Gabor,

Good news on the thermal break - Johnny at Cerini's just listed this as a standalone part in the last hour (nothing to do with my prodding him LOL), so you can get one without buying the whole kit!

I am going out to buy one for my second machine now!

Tim
If I could just like crappy coffee again, it would sure save a lot of time and money!

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JohnB.
Supporter ♡

#17: Post by JohnB. »

It's nice to see the gasket available separately again. I tried it stock & with that extra hole below the pipe hole closed off. I preferred the temp profile with the hole closed off but try it both ways & see what you think.
LMWDP 267

SpaceTime

#18: Post by SpaceTime »

I agree John - I have been trying to find a good priced alternative (partly combing through old threads that I saw you participated in too ;-)), and did find ULTEM remnants, etc... but for $15 at Cerini's for the pre-cut, right sized gasket, it is a no-brainer.

Johnny (at Cerini's) is breaking out lots of parts, VERY nice to see.

Tim

EDIT: I will try the "hole closed" option - thanks for the tip. One of my Cremina's that does have the heat break installed does have the hole open currently, so I will retrofit that one too!
If I could just like crappy coffee again, it would sure save a lot of time and money!

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naked-portafilter (original poster)

#19: Post by naked-portafilter (original poster) »

Thanks Tim! Bought two of them (just for sure :-))

SpaceTime

#20: Post by SpaceTime »

You are welcome Gabor!

One thing - I thought about this earlier after posting - the gaskets measure about 1/8th inch thick before installation and compressed in the 3/32nd to 1/16th range (they are semi spongy) depending on how much you tighten... and this is enough to justify slightly longer stainless bolts on your group. Many have done this, some don't, but I most definitely did... by the way, you don't have to over-tighten with these gaskets, there is no need to compress them down too far....

These longer screws in stainless can be hard to find, but I went back out to Cerini's, and voila - there they were! I pinged Johnny and he said these were slightly longer to accommodate the thicker gasket... about 4mm longer which is perfect.

http://www.cerinicoffee.com/stainless-s ... hines.html

Highly Recommended. I have an set on the way for my second machine!
If I could just like crappy coffee again, it would sure save a lot of time and money!