The Day Malachi Stopped Worrying and Learned to Love HXs

[HB]

(split from Fiorenzato Bricoletta - A Pro's Perspective by moderator...)

Honestly... I'm starting to get into HX machines. I like that I'm able to futz around with brew temp without having to change the brew temp setting, wait for it to stabilize, etc.

<insert sound of jaw hitting floor>

[malachi]

I know, I know...

I'm a bit frustrated with the lack of Intra-shot stability I'm seeing (as compared to the temp-stabilized Lineas Mistrals and Synessos). I don't know what's causing the lack of clarity in the shot - and it could well be inherent in the HX design (in which case I'll take back all I said about being into the machines).

But I really do like the fact that I can take an espresso and pull consecutive shots at slightly decreasing temps to determine effects on flavour - or that I can take a blend and experiment with the results of various combinations of brew temp and dose... all quite quickly and easily.

[Abe Carmeli]

But I really do like the fact that I can take an espresso and pull consecutive shots at slightly decreasing temps to determine effects on flavour.

This is true only to a point. Sooner or later you will hit the preimposed temp restriction of the boiler pressure stat. You cannot outrun it or bypass it. The range you will reach in temp control on a H/X machine is significantly smaller than you would with a dual boiler. When you are counting you Mississippi's on your way down the temp scale, you are more likely affecting the first 10 seconds of the shot, but not the tail of it. You will see a declining profile of brew temperature within a shot which is in sharp contrast to the temp controlled Linea or the Synesso. This may account for some of the differences in taste between your home H/X, and the commercial standard you used to work with.

[malachi]

This is true only to a point. Sooner or later you will hit the preimposed temp restriction of the boiler pressure stat. You cannot outrun it or bypass it. The range you will reach in temp control on a H/X machine is significantly smaller than you would with a dual boiler. When you are counting you Mississippi's on your way down the temp scale, you are more likely affecting the first 10 seconds of the shot, but not the tail of it. You will see a declining profile of brew temperature within a shot which is in sharp contrast to the temp controlled Linea or the Synesso. This may account for some of the differences in taste between your home H/X, and the commercial standard you used to work with.

I'm a bit frustrated with the lack of Intra-shot stability I'm seeing (as compared to the temp-stabilized Lineas Mistrals and Synessos). I don't know what's causing the lack of clarity in the shot - and it could well be inherent in the HX design (in which case I'll take back all I said about being into the machines).

[Abe Carmeli]

I'm a bit frustrated with the lack of Intra-shot stability I'm seeing (as compared to the temp-stabilized Lineas Mistrals and Synessos). I don't know what's causing the lack of clarity in the shot - and it could well be inherent in the HX design (in which case I'll take back all I said about being into the machines).

Yeah, I read it the first time. The point I'm trying to make is that there is no such thing as true range of temp control on a H/X machine, without adjusting the pressure stat. It's all an illusion. If you stayed within the targeted brew temperature of the pressure stat, you would not see such a declining temp profile within the shot. The temp variation will be ~1f from the end of preinfusion on. The reason you are seeing that monster intra-shot temp variation is because you are trying to operate outside that targeted brew temp.

[HB]

From the Brewtus thread...

As to my lazy man's flush chart, it will deliver 0.5c of dialed in Brew temp.

And now this thread...

The temp variation will be ~1f from the end of preinfusion on.

Do I detect selective hairsplitting (masked by Celsius to Fahrenheit conversion tables)?

[Abe Carmeli]

LOL, you are unduly confused my puzzled friend. I used f for the H/X comment because when testing H/X machines that was the scale I worked with. I used C for Brewtus because its temp control box uses that scale.

But the quotes you posted relate to two different things: One relates to intra shot temp variation (the f scale) and the other to hitting targeted brew temperature. They are not one and the same. You can hit your targeted brew Temp within 0.5c and yet your intra shot temp variation may be 0.

What else have you got?

[malachi]

Yeah, I read it the first time. The point I'm trying to make is that there is no such thing as true range of temp control on a H/X machine, without adjusting the pressure stat. It's all an illusion. If you stayed within the targeted brew temperature of the pressure stat, you would not see such a declining temp profile within the shot. The temp variation will be ~1f from the end of preinfusion on. The reason you are seeing that monster intra-shot temp variation is because you are trying to operate outside that targeted brew temp.

I'm actually not seeing "monster" variance. It's more like a 1F to 2F drop. I've experimented with various profiles per Dan and Jim's comments and have been able to reproduce their results - giving me this profile (which more closely mimics what I'm used to with a Mistral). Of course, my "gut" tells me that the odds are high that this decline may well be at the very least a contributing factor in the comparative lack of clarity in shots.

The total temp range I'm working within is only 6F (I've yet to find an espresso that tastes best at less than 198F or at more than 204F). So I'm not really going outside the target range in any meaningful way.

Your comment on the pressurestat on the other hand is quite valid and is one of the reasons why I would tend to suggest that the serious espresso freak consider upgrading to a commercial Sirai unit with this machine. It's one thing if you just want to pull a couple shots of your usual blend each morning but if you are going to be working with a large range of coffees and roast degrees and experimenting with interactions between these variables and dose and extraction temp then it would be worth the effort to swap to such a beast.

It's going to be interesting to (some day) test a home dual boiler after doing these HX machines. It's been a weird experience to go from the commercial dual boilers to home HX machines. I wonder if a home dual boiler is going to be one of those "thank god" moments or if I'm going to kind of shrug at the difference. I have no way to know. I think it's largely going to come down to a couple things. First - if they solve the shot clarity issues. Second - the logistical challenges of changing brew temps for experimentation purposes. Third - if they mimic the cup quality of a commercial dual boiler machine better than an HX machine like the Bricoletta.

[Abe Carmeli]

I wonder if a home dual boiler is going to be one of those "thank god" moments or if I'm going to kind of shrug at the difference. I have no way to know. I think it's largely going to come down to a couple things. First - if they solve the shot clarity issues. Second - the logistical challenges of changing brew temps for experimentation purposes. Third - if they mimic the cup quality of a commercial dual boiler machine better than an HX machine like the Bricoletta.

Taking the Brewtus as an example (it is the only home dual boiler I worked with):

1) Shot clarity - when compared with the Giotto Premium, there is improved clarity, but I am not familiar with the high benchmark - the Mistral to compare it to. It may not impress you.

2) Changing Brew Temperature: There is no challenge there, and it is easier than the stock Linea. It is two clicks on the control box, on the front panel, and a 5 minutes wait for the machine to adjust. However, the changes are in Celsius not Fahrenheit. Once it is PID'd, it will deliver Fahrenheit with the same ease.

3) Do they mimic the cup quality of a commercial dual boiler? I think that changing the pump to a rotary will bring it as close as possible to a commercial dual boiler.

[malachi]

I talked to David Schomer about the Brewtus just a week ago now. He was quite impressed and strongly suggested I take a look at it. He felt that it was a pretty ideal home machine. His comments mirrored yours quite accurately, though we did talk about replacing the pump and plumbing it in.

[malachi]

2) Changing Brew Temperature: There is no challenge there, and it is easier than the stock Linea.

I certainly hope it is easier than on a stock Linea!!!
(If you've never had the misfortune of trying to adjust brew temp on a stock Linea count yourself very lucky. To date I've burned myself multiple times, shocked myself badly twice and spent countless hours frustrated beyond belief trying to get to a specific brew temp. Infuriating.)

[HB]

Is there an unstated assumption that intrashot stability equals a slant-L temperature profile common to dual boilers? If so, does this really tell the whole story? Consider my hastily captured temperature profile below:

The temperature spectrum across the puck is huge until past the mid-way point. When we speak of the purported superiority of hyper-controlled brew temperature of water entering the grouphead, I wonder if it really matters except in terms of reproducibility of a given profile.

My nagging suspicious is that some blends simply perform better with one temperature profile versus another (e.g., "humped" or slant-L). On a related note, Peter Guiliano confirmed that his Toscano blend was sweeter on the Cimbali Junior during our group taste comparison. I asked him then why so many cafes prefer dual boiler espresso machines. He glibly responded, "I don't know. Maybe because they are easier for meathead baristas." This particular comment didn't make the final report though.

I talked to David Schomer about the Brewtus just a week ago now. He was quite impressed and strongly suggested I take a look at it.

I believe that can be arranged. BTW, I'll make sure you have more than an hour to check it out.

[Abe Carmeli]

I certainly hope it is easier than on a stock Linea!!!
(If you've never had the misfortune of trying to adjust brew temp on a stock Linea count yourself very lucky. To date I've burned myself multiple times, shocked myself badly twice and spent countless hours frustrated beyond belief trying to get to a specific brew temp. Infuriating.)

LOL, the sacrifices we have to put up with for a 1.5 oz of liquid. How about this for comfort: it is even easier than the Synesso. The control box is right on the front panel, in open view.

[malachi]

Hey Dan... I assume that's a stock Linea, right? How many groups?
Are you flushing the group right before pulling the shot? Keep in mind that Lineas are best under very heavy (constant or near constant) use. If the machine is not under load like that, you'll need to flush to heat the group and purge trapped water.

[malachi]

I believe that can be arranged. BTW, I'll make sure you have more than an hour to check it out. :wink:

Thank god - I'm fast but not in David's league clearly!

[Abe Carmeli]

Is there an unstated assumption that intrashot stability equals a slant-L temperature profile common to dual boilers? If so, does this really tell the whole story? Consider my hastily captured temperature profile below:

This is not a direct answer to your question but rather a side note: that temperature profile in your graph is a typical Brewtus profile in a flow rate of 2oz 25 seconds. Maybe to strengthen the claim that they do share the same temp profile. Here is a profile of 7 shots

But to answer your question, I think that the assumption is there. Whether is is justifiable, is a different issue.

[HB]

Hey Dan... I assume that's a stock Linea, right? How many groups? Are you flushing the group right before pulling the shot?

Yes. Two. Yes.

Peter and I collected this data on Counter Culture Coffee's espresso lab machine as a quick test, but the shape of the two curves is consistent with later measurements of the Cimbali Junior. Placement of the probes makes a big difference, so don't take particular values too seriously. It does however strongly suggest that the "holistic puck experience" is anything but uniform.

[malachi]

1 - it looks like the flush may have been "incomplete" or not performed immediately before extraction when comparing to my measurements.
2 - obviously you'll see a little more stability with the three group so that might account for some of the differences.
3 - the odds of a similar curve with the Linea and the Cimbali under "real world" use seem unlikely to say the least.

[HB]

1. Likely true.
2. Maybe.
3. Maybe.

I said earlier, this data was hastily recorded. Would you post your more carefully prepared charts? I expect there is a difference between top and bottom of puck temperatures (reports vary from a delta 4F to 10F), but I've only measured a few times.

[malachi]

I don't have a "top and bottom" chart - I was merely looking at the "top" portion and comparing it. I've never done any "top and bottom" evaluation as it seems to me it is so dependent upon coffee, dose, basket, distribution and tamp.