Brew Temperature Testing with Thermocouple

Need help with equipment usage or want to share your latest discovery?
RyanJE
Posts: 1519
Joined: 9 years ago

#1: Post by RyanJE »

Hello All,

In another thread, Jim S suggested testing brew water temp with a thermo couple wire in balled up foil (in the PF with no basket I assume).

I tried this and it seemed to give results, close to my PID temp. I am not sure if I was supposed to use an average of some sort, but the peak temp was matching or 1F above the PID setting. However, would the ball of tinfoil affect the temp reading? Also, i had to do it in my spouted PF which seems to retain heat MUCH better than my naked PF i brew with. Would that matter?

I am trying to get as close to a realistic number for brew temp, without a $600 scace!
I drink two shots before I drink two shots, then I drink two more....

hkeiner
Posts: 1
Joined: 9 years ago

#2: Post by hkeiner »

Hi,

I'll share my experience and conclusions on using a thermo couple to measure brew temps, which may or may not help you.

I made my own cheapo (scace type) tester by attaching a pressure gauge and thermo couple to a sealed off basket in a spare portafilter. I used a pin valve to control the flow of water through my tester to approximate the flow rate of a normal espresso shot. I was able to reliably test pressure at different flow rates controled by the pin valve, but I was not able to get reliable results measuring temps. The temp readings varied a lot, depending on the flow rate controlled by the pin valve, how I tweaked the placement/mounting of the thermocouple inside the basket, and what I put in the basket to substitute for coffee. I soon I realized I was just manipulating the tester to get a temp I wanted to see rather that really getting an accurate temp measurement. I gave up.

What I did find effective was to pull shots at a wide range of different temps (as shown on the PID display when starting a pull) and taste test to identify where the starting temp is clearly too low (sour) or too high (bitter) and then conclude on a the range of OK temps. I then split the difference and used it as my desired starting temp. I have since tweaked it up a few degrees but this got me started.

In the end, I concluded that whether the actual temp in the basket is exactly the same shown on the PID does not really matter. Setting the PID at an optimal starting temp (as determined by the taste tests) is what helps to get consistent results. At least it did for me.

Just my thoughts...

JonF
Posts: 240
Joined: 15 years ago

#3: Post by JonF »

I took an even more basic approach. Before I had ever heard of a scace, I just drilled a small hole in an extra portafilter basket and then measured temp while I brewed. Here the only trick is to make sure to plug any space around the thermocouple wire--I would use a fragment of toothpick. (If you don't you might have a bit of a mess . . .. :wink: )

User avatar
CoffeeBar
Posts: 644
Joined: 10 years ago

#4: Post by CoffeeBar »


samuellaw178
Supporter ♡
Posts: 2483
Joined: 13 years ago

#5: Post by samuellaw178 replying to CoffeeBar »

There's an easier way, but you have to be ready to sacrifice a probe. A responsive bead thermocouple snaked into the basket will work pretty well. I've used it for probably over 30 shots and still counting. It gives you the actual temp reading(including preinfusion) when making a real shot, rather than with a 'coffee-like' puck material and espresso-like flow rate. I felt it does fluctuate slightly(~<1C), but is representative and repeatable enough for tuning. The potential downside for this is, it is not a standard tool like Scace-II to allow comparison with other users.


The pressure may work, but the analog thermometer will most likely be too slow for a good reading. And no flow?

User avatar
CoffeeBar
Posts: 644
Joined: 10 years ago

#6: Post by CoffeeBar »

samuellaw178 wrote:There's an easier way, but you have to be ready to sacrifice a probe. A responsive bead thermocouple snaked into the basket will work pretty well. I've used it for probably over 30 shots and still counting. It gives you the actual temp reading(including preinfusion) when making a real shot, rather than with a 'coffee-like' puck material and espresso-like flow rate. I felt it does fluctuate slightly(~<1C), but is representative and repeatable enough for tuning. The potential downside for this is, it is not a standard tool like Scace-II to allow comparison with other users.

<image>



The pressure may work, but the analog thermometer will most likely be too slow for a good reading. And no flow?
Thank you brother Samuel for sharing. Yes I shall try your Suggestion( your method ) by sacrifice a probe. I also agree with you that the Analog should be less or slow in reading.

hope to learn more from you next time. Thank you again Brother Samuel :D

User avatar
AZRich
Posts: 207
Joined: 11 years ago

#7: Post by AZRich »

Ebay has very cheap multi-packs of bare wire thermocouples from China that are fast and reasonably accurate. If you are a roaster like me with a phidget, just connect the TC and use Artisan to record the temp from start to end of the pull as if it was a roast.
Rich

samuellaw178
Supporter ♡
Posts: 2483
Joined: 13 years ago

#8: Post by samuellaw178 »

CoffeeBar wrote:Thank you brother Samuel for sharing. Yes I shall try your Suggestion( your method ) by sacrifice a probe. I also agree with you that the Analog should be less or slow in reading.

hope to learn more from you next time. Thank you again Brother Samuel :D
Hi Wong,

Thank you for the kind words, but it's not a novel idea from me. I've merely read it somewhere on this forum and tried it. It's pretty useful! Also, note that it does leak slightly sometimes but not enough to affect the flow, probably less than 5ml throughout the entire shot.

Ideally, I want to get a Scace too but it's hard to get a seller here and for the price, I can almost get me a good machine(or another big conical grinder). Pretty hard to justify for home barista like us, but an indispensable tool for technicians/professionals. :(

SJM
Posts: 1819
Joined: 17 years ago

#9: Post by SJM »

I can email you a PDF with directions for building a thermofilter if you want.
I don't think I can attach or upload it here.
PM me if you are interested.

User avatar
CoffeeBar
Posts: 644
Joined: 10 years ago

#10: Post by CoffeeBar replying to SJM »


Thank you SJM @Susan :D

Post Reply