ECM Puristika temperature challenge

tompoland

One for @DavecUK I suspect. Thanking all contributors in advance.

I’m establishing a “grinder lab” to compare burr sets side by side. An important part

I have two Puristka’s equipped with Geisinger temperate probes in the group heads. I’ll upload a video in a new post below, but in the meantime my challenge is to how to complete simulatenous pours one the two macines and have the temperature to within one degree through the group head on each machine.

This is more challenging with a machine with a small boiler because the window of stable temperature is limied.

You’ll see in the video below and the temperature through the group head, as measured by the Geisinger probes, initially riases and then falls dramatically, presumably as the heated water in the boiler is replaced with water from the external resevoir.

My question is: whats the best method for having both machines pour the espresso as close as possible to thesame temperature? Note: I only need to do one pour per day simultaneoulsy on both bachines, not back to back pours.

tompoland

Here’s the video, in case that helps.

giampiero

Your video is a “frozen” photo 😊…edit…it was only a temporary issue with the video loading or else, anyway now is ok.

OPV at same setting, push the pump button without to move the lever until the OPV will discharge, so you will fill the boilers at almost the same level, of course all the PID parameters must be the same, wait at least 1 hour before the first shot so you are sure that the whole system has got a stabilized temp.

I did follow such simple method with my Carola, and for me was ok to reach a quite stable condition for subsequent test, but i never compared 2 of it, anyway the Carola has a different thermosyphon path, so maybe it could differ in the behaviors.

MediumRoastSteam

giampiero push the pump button without to move the lever until the OPV will discharge, so you will fill the boilers at almost the same level

The brew boiler is always full.

tompoland

giampiero oh that sounds promising. Nothing like the voice of experience Thank you!

PS I accidentally uploaded a photo instead of the video, I edited it quick smart but you may have been the victim of my initial e-tardness.

Cuprajake

What’s it like with coffee in the pf? Any slower to swing?

tompoland

Cuprajake temperature swing? good point. very good point. will check it tomorrow and reshoot the video. thanks for the idea. It could slow the fluctuation down.

giampiero

MediumRoastSteam yes and not, especially with a machine starting from a cold condition, i simply suggest this to be sure that both machine really start from a very similar conditions, no any “scientific” reason….maybe.

Cuprajake

Yeah possible., How much did you flush through in the vid?

I know it’s not an hx so not sure if a flush applies, on my old hx I would flush till the temp peaked. Then pull a shot,

Cuprajake

But really you shouldn’t have too.

@Beverast has one of these I’m sure

And @DavecUK maybe a better pid setting?

mobius

Would there be a difference when water is just free to run through, vs pressurised ?

In the former, the heat is being taken straight out, whereas in the latter (usual brew) there’s a much slower actual flow and added backpressure that could mean the heat loss is much less.

Beverast

mobius Yeah I would make that assumption as well. I have not done tests with external thermometers on my Puristika but under pressure the shots always come out nice and hot…usually have to let the brew cool for around minute or so before I can drink it. Would be good to see what the readings are with the pressure.

tompoland

mobius think you hit the nail on the head. Tx. Feeling kind of du’uh right now

Giphy - Feeling Dumb Jim Carrey GIF

tompoland

To your point Jake, I’ll load up the PFs tomorrow and run them and record. Dollars to donuts ECM will have it thoroughly well thoughtmout … with loaded baskets.

mobius

tompoland I mean, there will be a drop. I just pulled a shot on my classika (warmed for around an hour) and over the 36s the PID showed a 6 degree celsius drop (94 to 88).

I’d expect far less change in the group, and even the PID was back to 94 before I could finish writing this 😂

Much like Beverast, I don’t really worry about the accuracy of the temp to a scientific degree - I appreciate it’s important for your testing. I just know that my ECM gives me ‘great’ temperature shots, whereas the bambino didn’t, and everything that came out of it was almost cold within seconds (myself and my wife noticed a huge difference in both the temperature, and how long the drink stayed warm, on upgrading).

So it may be that such a drop, even in the head, is expected ? But that’s the way it brews. I think there’s absolutely value in the scientific method, but also maybe that you’d want something like the Decent for reproducible shots in that fashion 🤷🏻

MediumRoastSteam

giampiero yes and not, especially with a machine starting from a cold condition

Good point. 👍

tompoland

mobius right, makes sense tx.

And it’s probably common practice to compensate for the drop by increasing the boiler temp.

The main thing for me is to get the two machines pouring at a temperature as close to each other as possible.

And that of course is the reason for installing the Geisinger temperature probes. I’m glad I did because it’s giving me an insight that I wouldn’t have otherwise.

mobius

tompoland At times I wish that the flow control attachments could also measure temp (a two-in-one if you will). At the same time, I know I’d likely obsess over it, and not enjoy the espresso 😆

(It’s the main reason I didn’t go for a Decent, in the end. As an Engineer I figured it would be better to avoid too much analysis, although I still track/tweak the more analog aspects)

It’s great to see your experiments though, and will be interesting to follow the tests. My palette is nowhere near good enough to tell the difference in taste between even my Vario+ and my C40 (the latter I use now for consistent grind change), but I’m always intrigued when people talk about burrs, especially in relation to espresso.

Cuprajake

suppose though, if its repeatable its not a problem, its when its swinging uncontrollably,

tompoland

Cuprajake

Indeed, it’s not really about each machine hitting a specific temperature, it’s about them hitting the same temperature. Frankly, even if they both read 93 at the boiler and are pouting at 90, that’s fine because it’s not a cupping, it’s arout comparing two different burr sets

Therefore, so long as all variables are within a fraction of each other, it’s mission accomplised.

DavecUK

@tompoland You cannot measure brew temperatures running water through an open group, the flow rate has to be similar to coffee. If it’s not, you will get exactly the results you have. Flushing will also disturb things as cold water will enter the brew chamber and cause a potential change in temperature (which is a variable not a constant). This in itself introduces changes if a shot is pulled some 20s later.

The group head thermometers also have a variance against what’s shown in the basket for which I use 600 of SCACEII. I presume you checked at least the accuracy of the thermometers against themselves as well, in a container of near boiling water.

tompoland

DavecUK thanks Dave.

Yes calibration has been checked and I can confirm that both probes read teperature indentical to each other. And that’s the main thing I’m after.

Acheiving a similar temperature in the cup should be fine because the cups are identical, everything is in the one room, neither machine is next to a sunny window or anything like that. Beans will be the same and so on.

Don’t think I want to start using a Scace and I suspect that for the purposes of the grinder/burr comparision lab thingy, it’s not as important as it would be for say checking the accuracy or pressure/temperature on any given espresso machine.

As always, your input is noted and appreciated.

I’m off to dial in 2x Varia VS3s and video a simulataneous pour from the two (basket-filled this time) Puristakas. Will post the video here again.

Thank you to EVERYONE for your input. Your support in figuring this out is exceedingly helpful.

giampiero

@“tompoland” but if you want to compare the 2 Puristika temp behavior, making espresso, why you simply don’t make espresso, starting the machines at same conditions, and you check what temp you get at the group head thermometer during the shots?…or i missed something 🤔

tompoland

giampiero check what temp you get at the group head thermometer during the shots?…or i missed something

that would be too simple. 😀

seriously though, the reason is so that the temperature readings are visible, in real time as they pour, without having to manually measure them.

My OCD method is:

PID controlling the boiler temperature using the same make and model of high quality espresso machine to maximize the likelihood of consistency between the two machines
Measure the temperature of the water passing through the group head
Measure the in-cup temperature once the side by side pour has finished.

Once I’ve confirmed that the temperature is consistently similar across both the cups I can probably dispense with the last step.

Thanks for your help!