Monitoring Brew Temperature - E61 Groups - Page 2

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HB
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#11: Post by HB »

RapidCoffee wrote:For comparison, how well did the water dance method fare? I.e., were you able to improve brew temp reproducibility with the E61 TC adaptor, or did it simply provide verification that you could perform a "good" flush by ear?
For the first week, I pretty much ignored the adapter readout while flushing. That's how I arrived at 206F as the "right" temperature to stop flushing. When I did peek at the numbers, I was usually within 0.5F if it was one of the later shots and the pace was not faster than one every three minutes (i.e., leisurely weekend mode). For the first shot, the adapter readout confirmed what I had long suspected - the temperature spikes higher than normal - and had already compensated by subtracting a few seconds from the rebound time.

So yes, I was able to improve on brew temperature reproducibility, especially for the situations where the water dance method is tricky (e.g., a shot pulled between 1m30-2m30 after the last). Bob Yellin's simple rule of "flush two ounces if it's less than three minutes" works reasonably well for that situation, but the adapter enabled me to improve on it.

In summary, those who worry about the complexity of HX temperature management have a solution that a half-blind one-armed barista suffering from a mild case of AADD could not screw up.
Dan Kehn

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HB
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#12: Post by HB »

The prior chart only showed thermofilter readings. Below is an example of the two location readings shown together. To demonstrate the attenuating effect of the group, the adapter reading was taken from the bottom of the well (nearer the HX exit), not turn "D" as Eric's instructions suggest.

Image
Temperature within the valve chamber exit (blue) versus thermofilter (red)
Dan Kehn

BobY

#13: Post by BobY »

This is really interesting stuff! I've received my adaptor but haven't had time to install it yet. I plan to run a series of data-logged simultaneous comparisons between Greg's and Eric's device on my Andreja Premium with many different "starting temperatures" (time between shots) etc., as soon as I get a little time.

Dan or Eric (or any other adaptor owners with experience): Can you comment on the position of the probe tip and its effect on the results, beyond what is stated above. IOW, before I go ahead and install the probe, given the experience to date, is the best place to position the tip still the one described in Eric's "04" instructions? Eric's instructions are very precise as to where the tip should be positioned.

I know you (Eric) don't own an HX machine.

BobY

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another_jim
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#14: Post by another_jim »

Thanks for the data, Dan.

This is good news. I was sceptical about how well a thermocouple sealed into a tube would work, since an experiment Andy and I did 2 years ago using a hollowed out 5mm screw to house the TC failed due to the lag between the leading and the actual temperature (that speed up of the flush temperature drop after it gets to around 96C or 205F is a killer for any slow temperature reading setup). Obviously, the 1/16th tube insulated by the nylon ferrule is a very different animal from a hollowed out brass screw losing heat to the rest of the grouphead!

... And this certainly beats getting a bare TC under the screen and gasket, since those get chewed up every few weeks.
Jim Schulman

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erics
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#15: Post by erics »

Hi BobY -

Certainly I believe installing the probe as specified in the installation manual is the "correct" position. I even went so far as to inquire about a CFD (computational fluid dynamics) program to optimize probe position but the fact that average fluid velocities are so low (0.953 fps) in this area rendered that idea moot.

The heat transfer antics in the water flow path within the grouphead of ANY machine are complex and the closer you can get to the actual point of delivery, the better off you are from an information standpoint. The best, to date, is certainly Greg's Thermofilter. Next would be his (and Sean Strugnell's) drilling/tapping the grouphead in the dispersion screw area.

Omega HTTC thermocouples are different from their TJC or TJ series in that the HTTC's are a hollow tube (low cost) while the TJ and TJC are filled tubes. Omega felt there was no difference in response and the benny is that the HTTC lets the wire do the bending. I have a 1.5" HTTC here (specifically for Silvia) that I hope to install today and run some simple tests as in the FAQ section of the manual.

Hi Jim - the nylon ferrules are just there for ease of thermocouple replacement and movement - not for insulation. The thermocouple junction itself is located within the tip of the probe. Yes, I too remember Andy's screw modifications.

Eric S.

BobY

#16: Post by BobY »

Thanks Eric. I'll be very interested in your impressions of the difference(s) between the TJ and HTTC series after you do your testing because I have both options.

BobY

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another_jim
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#17: Post by another_jim »

erics wrote:Hi Jim - the nylon ferrules are just there for ease of thermocouple replacement and movement - not for insulation. The thermocouple junction itself is located within the tip of the probe. Yes, I too remember Andy's screw modifications.

Eric S.
Hi Eric,

I realize the ferrule is a seal; I was just speculating about its thermal properties. In Dan's graph, your sensor leads the Scace device's attenuated response by about 3 seconds, which seems about right (since the Scace device is affected by the baffling material in the basket). When I compared the hollow screw with a Schomer device (somewhat more attenuated than the Scace device), the graphs were reversed, with the screw slowing down the TC response to the point of uselessness.

The tube for the TC you're using may be more conductive than the brass screw, but I was speculating the nylon insulated it from the rest of the group, allowing the whole assembly to change temperature much more rapidly.
Jim Schulman

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erics
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#18: Post by erics »

Lots to reveal -

First, I had my old thermocouple (Omega TJC, Type T, 2.0 inches) positioned about 1/4" deeper than I should have. This is great, right? I write the instructions and can't even follow my own advice.

I replaced the TJC with the 1.5" HTTC, positioned correctly this time as per the instructions and I am a "happy camper". The HTTC, being a hollow tube, cools off quicker than the TJC, but responds beautifully to temperature changes. I had both the HTTC and the Thermofilter plugged into my meter but had the reading interval set to 10 seconds versus 1 second because of another project. It's a shame because that was a good shot, starting with the adaptor reading 190.2 and the thermofilter reading 183.7. The "my fault" 10 seconds readings were: Adaptor 190.2, 202.1, 204.6, 205.0, Thermofilter 183.7, 198.4, 199.4, 200.9.

I like the HTTC from a performance standpoint but the itty bitty wire would maybe bug me if it were exposed. I remain convinced that the proper probe location is as per the instructions but hey - that's what makes this a great forum.

The only way to get a SS braid is with the TJ series if you're big on looks.

The TJC offers wire size and Teflon covering identical to the Thermofilter.

The HTTC offers small wires but no bending necessary.

I think I'll order another TJC tomorrow and position it properly this time around. I am obviously interested to see how it does from a performance standpoint.

Maybe I post some graphs tomorrow.

Eric S.

BobY

#19: Post by BobY »

FWIW I did some measuring today with just the two TC types to check out response times and hands down, the HTTC responds faster; in fact it's an almost instantaneous response. That's the one I'll be installing with 1 measurement per second set up on my Extech.

BobY

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erics
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#20: Post by erics »

At least you could have signed your response with "Bob (I'll give the other guy a chance)Y" :)

I agree with your comments on response, Omega seemed to think they were comparable. I'm also going to see if I can get the HTTC with fat wires.

Take this kindly as I know you will and as I believe you know - it takes a lot of playing around before you draw conclusions.

Eric S. (still set up to do measuring so I will suffer in the AM for the sake of science)