SB E61+PID, Episode 1: A rude awakening about temperature stability - Page 3

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Giampiero

#21: Post by Giampiero »

1 hour to stabilize the group head seems a bit a long time, are you discharging steam/hot water or flushing water from the group head before switch off the machine?

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HB
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#22: Post by HB »

boren wrote:I'll perform the test I described above, in comment #12, and will decide based on the results.
As a mentioned earlier, I don't think the grouphead thermometer will yield meaningful measurements, especially for singles. A simple foam cup measurement would. But if you want to try your steps above, some comments:
boren wrote:1. Let the machine warm up for 1 hour, with the PID set to 95c (as is my default preference).
2. Flush for 6 seconds (this is up from my regular 4 seconds, which seems to be too short)
3. Brew a single shot (11.5 gram, dialed in to produce 23 gram espresso in 30 seconds).
4. Finish by lowering the lever all the way down. Avoid releasing any excess pressure even if the pressure gauge shows abnormal numbers.
5. Wait 1 minute, then brew another shot (repeat 5x times).
Shorten the flush at #2 to clear the screen only, 1 or 2 seconds, after the first shot. More than that will only destabilize the brew temperature. As for #4, there's nothing abnormal about the pressure gauge reading when idle. See What is normal pump pressure at idle? for explanation. For #5, increase to 90 seconds; for single boiler E61s, I would expect 90 to 120 seconds to be its sweet spot temperature-wise.
Giampiero wrote:1 hour to stabilize the group head seems a bit a long time...
I've tested more than a dozen E61 models and thought the same thing.
Dan Kehn

JRising

#23: Post by JRising »

boren wrote:Then why do they even make non-HX machines with E61 groupheads,
People buy them. People see an E61 grouphead as an identifiable trait of a good machine.
It's like when car manufacturers put those ironing boards on the trunk lid of a car that doesn't have anywhere near the aerodynamics to develop lift and need a spoiler. It's just going to add a bit more drag, but it sparks a thought of "maybe it's fast, or at least not awfully slow" somewhere in the subconscious. People see a stainless steel box with an E61 grouphead on it and think "Ooooh, I'm getting a real machine for the price of the disposable things." and they buy it.

Bluenoser
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#24: Post by Bluenoser »

.. there are only two ways to know if your brew water is good..
a) you have a great palate and you can tell the difference between 2F differences in extraction
b) measure your brew water accurately..

A measurement way back at the boiler only hopes it can accurately approximate your brew water temp.. A group thermometer is closer, but still not at the screen.

Such is a hobby.. it forces you to do more work than you want to. Even as an engineer, the last thing I wanted to do was buy a group head thermometer for my HX because videos from a major vendors' video showed my HX to be as accurate as a Dual Boiler. (and that added $200 to my cost) When I got bad tasting espresso, I had to buy the thermometer as my only way of troubleshooting the problem.. Then I borrowed a scace from a very generous HB user because the group thermometer explains some problems I was having, but not all. Only then did I get data that I could use to explain how my particular HX works (which BTW was not as the vendors' video showed)..Once I had that, I could quickly develop a workflow that gave me the brew temps I needed for multiple shots. There was no shortcut in my case. Complain bitterly as I might.. such is the reality of those machines.

Those spikes you see in the group thermometer (as long as they are less than 5 seconds) get "eaten" up by the E61.. It is like a capacitor in electronics, smoothing fluctuations in voltage.

BTW, a simple measurement at the screen would allow any user to not have to go through the gyrations you are experiencing, be it HX, SB or DB.

boren (original poster)

#25: Post by boren (original poster) »

Giampiero wrote:1 hour to stabilize the group head seems a bit a long time, are you discharging steam/hot water or flushing water from the group head before switch off the machine?
I always flush water after each shot, to clean the screen. I don't flush again before turning off the machine.
HB wrote:As a mentioned earlier, I don't think the grouphead thermometer will yield meaningful measurements, especially for singles.
If measuring at the grouphead one shot is at 87c and another is at 95c, isn't that meaningful? Do you see any chance that such measurements could result in temperature at the coffee bed being similar to each other? I'd expect the second shot to still be far hotter than the first.
Shorten the flush at #2 to clear the screen only, 1 or 2 seconds, after the first shot. More than that will only destabilize the brew temperature.
Ok, will do. I actually prefer flushes to be short, as long as temperature is stable.
As for #4, there's nothing abnormal about the pressure gauge reading when idle. See What is normal pump pressure at idle? for explanation.
My machine is not plumbed in, but regardless, I'll just ignore these readings. The machine otherwise seems to behave correctly.
For #5, increase to 90 seconds; for single boiler E61s, I would expect 90 to 120 seconds to be its sweet spot temperature-wise.
I'll do as you suggest. If the machine can provide stable temperature in some very specific (ideal) workflow it's at least a place to start.
JRising wrote:People buy them. People see an E61 grouphead as an identifiable trait of a good machine.
I don't think that's the whole story. Machine like the Lelit Bianca and ECM Synchronika use an E61 grouphead without HX, yet they still manage to produce excellent coffee with an even better user experience compared to their HX counterparts. I don't think the Bianca and Synchronika are failed designs. There has to be more to this story than the thermosiphon being designed for use with HX.

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hankbates

#26: Post by hankbates »

Seems to me that we are trying to make a batch process into a continuous process here. Everything stops and starts when brewing coffee, driving down the expressway with your cruise control is pretty much steady state.
Sure, the E61 thermosyphon and PID both help to maintain stability, but an equilibrium really cannot be achieved when coffee grounds heat up from incoming water, group temperature goes up and down, pumps start and stop, etc.
Guess I'm pretty happy with getting things close to optimum with my Livia 90 after years of using a LaPavoni. We aren't going to find this holy grail, but it is fun to try.

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HB
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#27: Post by HB »

boren wrote:If measuring at the grouphead one shot is at 87c and another is at 95c, isn't that meaningful? Do you see any chance that such measurements could result in temperature at the coffee bed being similar to each other? I'd expect the second shot to still be far hotter than the first.
Bluenoser covered this already, but maybe a simple analogy will help those following along: If I measured the temperature a few inches from the heating vent, I would conclude the room temperature varies 30+ degrees throughout the day. Where I'm sitting, which is what really matters, it only varies by a degree or two.

OTOH, if you measured with the simple foam cup temperature method and saw a 8C variance, that'd be a problem. Based on what I've read here, I'm not convinced there's an equipment-related problem. :wink:
Dan Kehn

boren (original poster)

#28: Post by boren (original poster) »

Ok, I'll add a foam cup measurement. Can't go wrong with another data point :-)

Just to make sure I have the correct set up in mind, should it look like this?

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HB
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#29: Post by HB »

Yes. For ease of reference, here's a good photo from a recent discussion:
BaristaMcBob wrote:I measured the brew water temp by holding a styrofoam cup under the group. Exactly like this, except I used a faster responding digital kitchen thermometer:


<snip>
The shorter the cup, faster the thermometer response, and tighter the fit to the grouphead, the more accurate the temperature measurement.
Dan Kehn

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cafeIKE
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#30: Post by cafeIKE »

boren wrote:5. Wait 1 minute, then brew another shot (repeat 5x times).

Would this be a more realistic and useful test?
Few can grind & prep at that rate. More like 3 minutes.