Hi there,

Long time lurker but decided to register and starts asking question, hope it is ok

Coming from down under, I tend to lurk more often in our local forum. One thing has been bothering me for so long: It's often claimed by the sponsors/sellers here that we Australian have properly configured HX machine (grey import excluded) and there's no need for cooling flush (so the inference is you have to buy from them - the official importer - to get a properly calibrated machine ). Some even said that it is as consistent as a DB.....that aside.... My understanding is they have their machines installed with a properly sized thermosiphon restrictor so that there is no flash boiling/overheating as in conventional HXs, and they're consistent shot after shot(a question mark as I have not seen any solid evidence)

If the key is finding the optimized/calibrated restrictor in the thermosiphon, why isn't this the standard for the US market? If it is a matter of finding the right orifice size for a particular machine, why won't US vendors start making that standard (so consumers don't have to bother with all that cooling flushes)? Why are manufacturers still producing machine that burns coffee (and make the properly configured machine exclusive to Oz)? Or maybe I should ask it this way : is there any coffee that actually benefits from boiling water?

I did do my own research before posting. I have a general idea how restrictor works on affecting E61 HX idle/brew temperature. And from gathering info, seems that the latest ECM Technika and Rocket Evo, and the older VBM have restrictors installed. Are these restrictors optimized/'calibrated' properly to give +/-93deg C in the group head? I see that cooling flush is still needed? Does that affect the recovery time, by how long?

Appreciate the wealth of knowledge on this forum.


Cheers

Australia suspended the laws of thermodynamics.

Or perhaps the distributors and resellers are offering misguided advice, for whatever reason.

Which do you think it is?

Australia is pretty special...

nuketopia wrote:Australia suspended the laws of thermodynamics.

Or perhaps the distributors and resellers are offering misguided advice, for whatever reason.

Which do you think it is?

Espresso machine retailers can be like politicians; something is "true/false" if they say it is. The laws of physics are a complete mystery to most of them. Depending on the machine and the version of the E-61 group used, it is possible to minimize the cooling flush at the expense of some of the steam pressure. The only way to eliminate it altogether would be to hold the boiler at slightly above brew temperature (so no steam) in a climate controlled room, with perfect insulation for all pipes.

Alan

MadBarista wrote:(and make the properly configured machine exclusive to Oz)?

They don't. It's just a trick to make you buy from a particular reseller. I think I now understand why so many cafes in AUS and NZ make such a terrible coffee - baristas (or rather cafe owners) here were convinced by salespeople that they operate equipment that was "properly calibrated exclusively for them". Those sales people probably also convinced owners that they will save $$ (on water and electricity) if:
- baristas do not do the cooling flushes before shots, as needed
- baristas do not backflush after each shot
- baristas do not clean the shower screen after each shot
It's all lie. You would never do that at home. Because you will immediately notice the difference - burnt, acrid-sour combination, reminiscent of a stuff from a nearby cafe.
It is one of the reasons why bother with coffee preparation at home - you can do it properly, your way, you can take time weighting the dose, preparing each shot, do WDT, throwing it into sink if you do not like it - things that cafes just cannot afford.

MadBarista wrote:Or maybe I should ask it this way : is there any coffee that actually benefits from boiling water?

Sure there is
Here is what you do: because the boiling point of water drops with elevation, one just has to climb a mountain high enough, where water boils at 92-96C. There you can just pour boiling water onto coffee without any harm to the resulting beverage.

MadBarista wrote:If the key is finding the optimized/calibrated restrictor in the thermosiphon, why isn't this the standard for the US market?

If a flow restrictor in the thermosiphon could solve all the problems, we all would have one Since they sell equipment to people who might live in different conditions, at different elevation over the sea level, different room temperatures, different water temperatures, etc., etc., there is no one restrictor that would satisfy everyone's needs. Besides, the restrictor will be one of the first things that would block with scale if water is too hard...

For reference, Ideal brew temperature management by HX espresso machine type covers my understanding of the impact of HX design on temperature management. Specifically to your question:

MadBarista wrote:Are these restrictors optimized/'calibrated' properly to give +/-93deg C in the group head? I see that cooling flush is still needed? Does that affect the recovery time, by how long?

The short answer is yes, even well-tuned E61 HX espresso machines require that the barista is aware of temperature management. What I believe has happened over the years is more manufacturers have adapted their single group E61 models to the slower production pace of a home barista, which means less need to flush. The ECM Technika IV Profi Review touched on this point:

HB wrote:The Technika is tuned to reduce the need to flush (hence the "short" and "mini" flush described in the video), but this increases its shot-to-shot recovery time to a minimum of 2 minutes. The temperature reproducibility is best with recovery time around 3 minutes.

The above is typical behavior of a Mixer type of HX espresso machine, i.e., modest flush, medium to slow recovery, initial rising then falling brew profile. Over the years, I believe the desire to simplify temperature management for slow paced environments has resulted in more models tuned as Mixers rather than Dragons.

The so-called "uncalibrated" E61 HX espresso machines perform better under heavy load; my assumption is that they were originally designed with small cafes in mind where (a) the operator knows what they're doing, and (b) they occasionally have the need to make back-to-back drinks. When these unruly espresso machines found their way into consumer kitchens, the assumptions (a) and (b) no longer applied. As the latter group grew, more manufacturers recalibrated their E61 HX designs for the expected slower pace. Some of the early adopters of this strategy touted it as an advantage to potential buyers, but nowadays most E61 HX espresso machines are tuned this way, so it's really more of a marketing claim than a genuine distinction.

Wow, what a completely different response/perspective here (over there it almost felt like you'd be hushed if you try to question the sponsors/authorities).

Sounds like it is impossible to calibrate the machine to every situation - fair enough. But let's say if the operating condition is predictable (for 90% of the consumers, that would make 90% happy customer and the 10% can buy a DB ), what would be the expected performance of an E61 HX with an optimized restrictor?

One of the gold standards for temp stability is NS Aurelia - it's an HX with a properly tuned thermosiphon. So there is a sliver of possibility. However, it is not E61 and the Aurelia has probably been engineered intensively. So why it has not been done on E61 - is it physically impossible due to the exposed group head, or not enough effort has been put in, or has it been done but not widely spread? With the many talents here, I would think it must have been explored at one point...

It'd be awesome to have an E61 HX with the temp stability of Aurelia.

The scale is a valid point and could very well be the reason. However, if we are feeding the machine with hard water, restrictor or not, probably doesn't make much of a difference - problem is bound to happen, just a matter of time.

Cheers

p/s: just saw HB's post above as I was composing my post. Awesome info, thanks!

If every home had the exact same air circulation and same ambient temperature, and every user turned on the machine and let it idle for the same amount of time before pulling the first shot, and then every subsequent shot was executed at the same, predetermined interval, then maybe they could make that claim. I suggest looking up the definition of "puffery."

I suppose, looking at it from a sellers standpoint, it is true. You do not need to do a flush with an E-61 in Australia. All you really need to do is get accustomed to inconsistent results and poor espresso on a massive scale. If there are folks there who don't get it, have them read the story of "Goldilocks and the Three Bears," and tell them to ignore all the third choices that she makes throughout the story.

SCENE FIVE: Goldilocks and the Two Espresso
"Ooo. This espresso is too bitter and over extracted!"
"Ucky.This espresso has no body and is under extracted!"
"I think I'll have tea."
[from offstage we hear] "SOMEONE CUE THE WOLF! LET'S GET THIS THING OVER WITH!"

For the past hour, I've been digging links - from HB's review to god-know-where. Then I found there's this one graph from erics.

Looks pretty impressive for a no-flush routine. The downside is of course the attenuated steam power at 0.8 bar.

Vibiemme temperature too high during extraction?


But bottom line is (from what I read so far), a flush is still needed to manage the brew temp. If you have a 'calibrated' hx, you can get pretty consistent and the pain/flush is much shorter - as HB had shown in the ECM review. And now I know it's not just an Australian thing - more like model and brand specific.