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Monitoring Brew Temperature - E61 Groups

Postby erics on Fri Mar 24, 2006 11:25 pm

Hi -

I have "designed" and have manufactured (for me) a custom fitting to take the place of the M6 x 8 allen-head screw found on E61 groupheads. I have termed this fitting the "Thermocouple Adaptor", but it is also a "Thermometer Adaptor". The adaptor for E-61 machines is available only in stainless steel and will accept ONLY a 1/8" thermocouple (of your choice) or the modified digital thermometer I offer. It replaces the M6 allen-head screw by screwing into the grouphead and sealing with a copper washer exactly as the existing M6 screw in your grouphead. The 1/8" thermocouple or digital thermometer stem is sealed to the adaptor by means of replaceable nylon ferrules. No drilling, tapping, soldering, brazing, cutting, teflon tape, or epoxy are required. Installation instructions for the adaptor can be found on my FTP "website" in the file entitled "DigThermAdptr7.pdf": http://users.rcn.com/erics/. Click on the file and save it to your computer. Please read these files carefully as they are designed to answer most questions concerning installation and use and even include a "quickie" install pictorial at the end. You might also want to read the file entitled http://users.rcn.com/erics/Digital%20Thermometer%20Build.pdf as it gives a pretty good pictorial of the build process of the thermometer kit - if I do say so myself. :)

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The thermocouple/thermometer adaptor kit consists of the adaptor with copper washer, a spare copper washer, a spare nylon ferrule set, and a plug to seal the adaptor should you wish to or need to suspend temperature measurements. After inserting your thermocouple and attaching it to your appropriate meter, you can easily observe and/or record brew and/or flush water temperatures approximately 1.25" upstream of the espresso puck/empty basket using your normal espresso brewing/flushing practice. EQUALLY IMPORTANT, you will be measuring a temperature that is very representative of grouphead temperature.

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OK, I want one, what do I do now? - Read the installation instructions, then read the installation instructions and finally read the installation instructions again appropriate for the adaptor kit you desire. Complete ordering, inventory, and pricing information can be found on my FTP site in the document entitled "Pricing_Inventory_Ordering". You need to be somewhat mechanically inclined and understand the use of thermocouples and appropriate temperature meters OR have a good friend who is. The adaptor kit prices which include shipping via USPS 1st Class are: E-61 Thermocouple Adaptor - $72, Digital Thermometer Adaptor Kit with user switchable degrees F/degrees C - $104.00. Shipping outside of the US via USPS Priority Mail (small flat rate box - partially trackable) is $32 additional. Paypal is accepted and is the preferred method of payment as described in the Pricing_Inventory_Ordering pdf document available here: http://users.rcn.com/erics/ .

COMMENTS/SUGGESTIONS on the instructions or questions of a general nature that could be included in the FAQ section of the install manuals would be GREATLY appreciated. Thus far, a total of two thousand, two hundred and thirty-seven (2237) thermocouple adaptors and digital thermometer adaptors have been shipped to users of varying ability in 36 countries which include Australia (64), Austria (3), Belgium (4), Brazil (1), Canada (68), Chile (1), Czech Republic (3), Denmark (22), Dubai (1), England (24), Estonia (1), Finland (10), France (3), Germany (7), Greece (1), Guam (1), Hong Kong (7), Ireland (2), Israel (4), Japan (2), Korea (1), Malaysia (1), Mexico (1), Netherlands (48), New Zealand (13), Norway (7), Poland (11), Puerto Rico (1), Romania (2), Russia (21), Saudi Arabia (2), Singapore (6), South Africa (1), Spain (1), Sweden (7), Switzerland (1), Ukraine (2) and, of course, the United States (1882).

Stock Status: Digital Thermometer Adaptor Kit in F/C - 129. Replacement thermometers are always available. (calibrated exchange service).

THE 2200th ADAPTOR WAS SHIPPED TO THE UNITED KINGDOM

It is always best to check stock status BEFORE you place an order as this post is, maybe, edited on a monthly basis. Edited 09/13/2014 to reflect improved text, adaptors shipped, and current stock status. Thermometer construction has been vastly improved. New thermometers are assembled without the use of any hot melt glue as the thermistor wiring (and thus the thermistor itself) is held in place with a wedged small brass or aluminum tapered tack. The lower housing of the thermometer has been machined slightly to allow for much easier assembly or user repair and the latest units include soft-touch buttons and auto-shutoff to extend battery life. The depth adjustment is no longer necessary as the depth is now fixed at the proper dimension with the newly designed probe housing. All improvements are easily retrofittable.

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Acknowledgements:

Thanks to Andy S. for suggesting I go with an E61 adaptor vice just one for Silvia after my original post on AC and to Sean L. for suggesting nylon ferrules and to Greg S., Sean S., and Dave S. for devising all sorts of innovative methods of measuring brew water temps. I also thank Lino V. for his unselfish OK to use several of his E61 group drawings contained in the thermocouple adaptor, digital thermometer, and adaptor tidbits documents.

The original posting in March of 2006 was cross-posted in its entirety to AC and CG.

Eric S.
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Postby Strugs on Mon Apr 10, 2006 1:40 am

I just wanted to weigh in on what Eric has done here. If you have an E61 machine, I have only one piece of advice for you....run out and get one of these bolt temp probes. While it is true that some espresso blends can be brewed within a range of ± 5 degrees, these blends are the exception, not the rule. In my opinion, the ONLY way to get the best out of your Spro is to ensure that your brew temps are (a) stable; and (b) consistent. As some of you know, the temperature monitoring mod on my machine is located further down the brew path than the one Eric has produced. However, I also made a similar version of Eric's probe a short while before doing my current mod, and there is not a whole lot of difference at the end of the day.

After using my probe for several months now, I would never dream of using an E61 without a temperature probe. Think of it as driving a car without a speedometer. Sure you can get a feel for how fast you are going, but try to explain that to a cop when he pulls you over.

So - major props to Eric and kudos for his insistence of the donation to CoffeeKids as part of the price. I spent well over $300 on the trial and error method of my current temp monitor rig. Eric has done all the hard work on this - his price is a steal for what is probably the most useful mod you can make on an E61 machine.
Sean
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Postby Ozark_61 on Thu Apr 20, 2006 10:00 am

I just posted a long reply at CG - but a very hearty second to what Strugs said. You'll not be able to live without this once you try it!
Cheers,
Geoff
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Postby HB on Wed Apr 26, 2006 10:14 pm

Greg milled his Astra to insert a temperature probe (discussion), Dave detailed a low-cost alternative in No More Guesswork! Naked Truth of E61 Temperature Revealed, Sean fabricated his own adapter as documented in Thermal Obsession...

... and now Eric has kindly done all the legwork to bring us a ready-made package:

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E61 adapter with 1/16" sheathed thermocouple

Although I've been on respite from "gadgets" as part of my study of holistic barista techniques, the attraction of his offer was irresistable - I e-mailed Eric the same hour that I read his post. The adapter arrived last week and I installed it over the weekend:

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Eric's instructions are thorough and packed with well-drawn diagrams. However, in my excitement to get it installed, I initially didn't insert the probe at the depth shown above, but rather near the bottom of the hole, directly into the valve chamber. Needless to say, the temperature measurements fluctuate dramatically in that location. Moving it closer to the location Eric suggests does produce more steady readings, but I'm intrigued by how accurately the sound of the "water dance" predicts the chamber temperature.

For HX owners who want to end their uncertainty about the proper cooling flush, this adapter / thermocouple combo looks very, very promising.
Dan Kehn
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Postby RapidCoffee on Wed Apr 26, 2006 11:32 pm

HB wrote:... and now Eric has kindly done all the legwork to bring us a ready-made package:

Although I've been on respite from "gadgets" as part of my study of holistic barista techniques, the attraction of his offer was irresistable...

I'm intrigued by how accurately the sound of the "water dance" predicts the chamber temperature.

For HX owners who want to end their uncertainty about the proper cooling flush, this adapter / thermocouple combo looks very, very promising.


Dan, is that a Vetrano install? Please continue to post your results. I've also been very interested in this device, just haven't had the time to follow up lately.

Thanks - John
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Postby HB on Thu Apr 27, 2006 1:00 pm

Yes, the adapter is installed on the Vetrano.

I plan to post temperature graphs reported by the thermofilter and adapter at different depths. For now, I'm evaluating it purely as an aid to managing the cooling flush. As my first test, I positioned the probe at the bottom in the valve chamber and followed my usual routine to see (a) what it read, and (b) if the end-of-dance technique was consistent shot-to-shot. The readings confirmed what we've said all along - nailing the temperature accurately based on sound is easy, especially if the shot interval is a few minutes minutes apart. At shorter, irregular intervals, it's difficult to judge with precision. That's where I am assuming the adapter's readings will prove most helpful.
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Postby erics on Thu Apr 27, 2006 8:18 pm

Hello Everybody -

I operate a PID'ed Silvia and observe "grouphead" temperatures via a Type T thermocouple and the thermocouple adaptor. I read the temps on an Omega HH506RA and am continually amazed at the grouphead's behavior from a temperature standpoint.

Silvia's performance is documented here: http://users.rcn.com/erics/ under temperature graphs and also in the FAQ section of the installation manual available in the folder entitled "thermocouple adaptor".

For now I make only Cappy's but they approach and, if I am patient, meet the quality of those served at Murky here in DC. For me, that's saying a lot because Murky is truly top quality.

Eric S.
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Quotable Quote
"If there's one thing I've learned after many in-depth espresso machine evaluations, it's that attempting to predict espresso performance from a spec sheet is utter folly" --Dan Kehn, Commercial non-saturated, non-E61 group heads


Postby HB on Sat May 06, 2006 12:45 am

The wife was out for the evening, so I ran a series of thermofilter tests using the TC adapter to judge the correct flush. In other words, I want to answer the question: Assuming one forgets about observing the water dance or listening for HX sputtering, how consistent are the brew temperatures if one just flushes until the meter says temperature X followed by rebound Y?

I had already determined that the proper temperature at the well depth for my routine (flush... rebound 30 seconds... pull) was 206F. Keep in mind that for the purposes of this test, I don't worry about what the adapter temperature relative to the brew temperature might be, as long as it indicates the same readings every time. I postulated that since we're really tuning the flush, it's better to read the temperature BEFORE it's attenuated too much by the group, so I placed the probe at the bottom of the well. As I reported earlier, the reading is changing quickly at the bottom, but that's reality. I see a very distinct "knee" right around 205F. The temperature moves slowly prior to that and then plummets just past it. For this particular machine, my assumption is that it marks the end of the HX over-temp water exiting.

The series was proceeded by a "warm up" flush (flush... wait a couple minutes... begin series). Preamble out of the way, below is my Friday evening results:

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Irregular pulls (3m, 1m30, 3m, 15m, in no particular order)

Some observations:
  • Grouphead is definitely cooler and the HX hotter after the machine is idle for a long period (see line in red; rises more slowly at first, spikes higher)
  • "Warm up" flush would spike well above the target brew range then settle down (this "high hump" profile was not recorded)
  • Adapter feedback made it easy to stay within 1F, although occasional outliers still occur, especially if interval was short (see blue dashed line with 200.4F peak temperature)
  • The adapter reading and thermofilter reading converge about midway into the shot; the thermofilter indicates a very slow decent towards the end and the adapter is reporting near flatline temperature from the HX (I did not show both readings on the chart above for simplicity).

The utility of Eric's adapter is plainly evident to me: By tuning the flush amount based on the adapter's TC reading, reproducible temperatures are easily obtained within ~1F. I wonder how well this holds up with the lowest-cost setup (approx. $20 digital thermometer + type K thermocouple) in place of my pricey rig (Fluke 54-II + special limits of error type T thermocouple).
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Postby RapidCoffee on Sat May 06, 2006 12:41 pm

Thanks for posting your observations! Very impressive brew temp stability and reproducibility, especially from an oft-maligned HX.

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?

Gonna have get me one of these thangs.8) Any chance my TM-125 ("cheapest thermocouple and meter on the planet") is adequate? If not, any suggestions for a more sophisticated TC/meter?

- John
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Postby erics on Sat May 06, 2006 7:48 pm

Hi John -

These thangs require a thermocouple other than what (I believe) you have with the TM-125 and I suspect that the read rate of the TM-125 may be highly filtered and not readily adjustable. Does the TM have a standard thermocouple connection or a miniature one? Another good choice for a meter is one of the inexpensive Ebay 1/32 DIN PID's from Auber or ColdFusion, i.e. SYL1512 or TET-7100 - essentially identical.

Eric S.
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