Expected differences between dual boiler and HX?

[cappadoc]

(moved from News and Suggestion Box by moderator...)

I'd love to see Dan throw down with a Brewtus. Any chance of seeing this in the near future Dan? I'm struggling with the HX vs. Dual Boiler decision.
Jeff Johnson

[HB]

Indeed, I was thinking about starting a thread asking what espresso machine reviews readers would like to see -- and I expected the Expobar Brewtus would be near the top of the list. Whole Latte Love currently isn't a site sponsor, but I did meet Todd Salzmon in Seattle at the SCAA conference and we discussed the possibility. No firm commitment at present.

Hmm-m, a very interesting writeup would be a "dual boiler smackdown":

• Expobar Brewtus
• Quick Mill dual boiler demonstrated at the SCAA (currently unnamed)
• La Spaziale S1 (update of the existing guide)
• La Marzocco "consumer model" -- hey, a guy can dream, right? (currently unnamed)

Needless to say, that would be a very ambitious undertaking.

Back to your original point, I agree, the whole HX versus dual boiler question is intriguing. To some extent, the Group Taste Comparison: Cimbali Junior versus La Marzocco Linea addressed part of this debate:

What are my own thoughts? I was scratching my head as I watched one of the participants tally the results. I unconsciously accepted La Marzocco as the de-facto standard based on all the positive press that I had read. My expectation of a lopsided victory in favor of the Linea simply did not materialize. As anticlimactic as it is to say, all the shots were darn good and if there was a difference, it wasn't much to get excited about.

So where does this leave you, the home espresso lover? The last comment above states it best: "This test proves that you can get 90-95% of the way to god shots with just good solid fundamentals." And obviously it helps to have a great espresso machine, which the Cimbali Junior proved itself worthy of the title.

The fundamental question I would ask: What differences do you expect to find in a dual boiler versus an HX?

PS: There's a number of threads on CoffeeGeek about Brewtus, such as the meaty discussion Brewtus Temperature measurements and more broad discussion A Week with Brewtus.

[sheygetz]

Hmm-m, a very interesting writeup would be a "dual boiler smackdown":

• Expobar Brewtus
• Quick Mill dual boiler demonstrated at the SCAA (currently unnamed)
• La Spaziale S1 (update of the existing guide)
• La Marzocco "consumer model" -- hey, a guy can dream, right? (currently unnamed)

Shouldn't the Reneka Techno be on that list?

sheygetz

[HB]

Sure. It will also help the Reneka Techno's popularity now that Whole Latte Love sells it (link).

[Walter]

Hi all,

having followed the discussions here for some time, I reckon it's time for me to de-lurk, since I've been also struggling with the decision HX vs. Dual-boiler for a while now.

The fundamental question I would ask: What differences do you expect to find in a dual boiler versus an HX?

Well, I'd say I expect a more linear temperature profile from the Dual-boiler and a HX-Hump from the HX - go figure...

Being a n00b to espresso (got my first machine - a Butterfly - some six months ago, have developed some serious addiction since and am already pondering an upgrade to another machine - currently it looks like Cimbali Jr vs. Spaziale Vivaldi but still open for suggestions), two months ago I'd have said it's a no-brainer: "Schomer sez Dual-boiler and temperature-stability rulez and the guy knows his business"...

Alas - I am no longer sure about that. After having become familiar with the proper flushing technique, I managed to pull some quite good shots from my Butterfly (E61/vibe. pump) in the past two months. And unfortunately I lack such a positive experience from the commercial machines I occasionally get a ristretto from. Everything I got served within the past two months seems mediocre at best, when I compare it to my coffee at home.

To cut the long story short: Which produces the better coffee? Slant-L or HX-hump? (And - yes, I know, the one with the better guy at the handle side of the portafilter...).

Is there a clear unambiguous answer? Does it depend on the coffee/roast? Personal preferences? Anything else?

----
Great forum and website, btw...

[HB]

Thanks Walter for delurking! I think that you've summed up the HX versus dual boiler thinking of many people (i.e., "Schomer sez Dual-boiler and temperature-stability rulez and the guy knows his business"). David Schomer has forgotten more about espresso than I've yet to learn, but the exhortations of the late-comer contest entry "Challenge Authority" resonate with me. And yet I've not revealed publicly (until now) that I've been plotting to open the discussion of this point...

My plan came to full fruition The Day that Malachi Stopped Worrying and Learned to Love HXs. Soon thereafter, Chris' Bricoletta review advanced the argument that neither design is inherently superior if the criteria is solely the in-cup result. Abe's upcoming Brewtus review will be addressing this question too, i.e., what considerations should gravitate you towards one choice or another. But publication is still a few weeks off and I don't want to risk misrepresenting his opinion, so I yield the discussion to my esteemed colleagues...

[malachi]

Well, I'd say I expect a more linear temperature profile from the Dual-boiler and a HX-Hump from the HX - go figure... :D

Actually, you can "mimic" the brew temp profile of a dual boiler (or at least a Linea) with an HX machine.

"Schomer sez Dual-boiler and temperature-stability rulez and the guy knows his business"...

But.... he's talking about commercial situations.

And unfortunately I lack such a positive experience from the commercial machines I occasionally get a ristretto from. Everything I got served within the past two months seems mediocre at best, when I compare it to my coffee at home.

Which continues to illustrate the key points.
1 - the espresso machine is probably the least important of the 4Ms.
2 - espresso is fundamentally subjective and personal.

To cut the long story short: Which produces the better coffee? Slant-L or HX-hump? (And - yes, I know, the one with the better guy at the handle side of the portafilter...).

You answered your own question.
Seriously.

But seriously... it depends. Assuming equal and very high skill it will depend on the coffee, your barista style (technique choices) and your personal taste in espresso.

Is there a clear unambiguous answer? Does it depend on the coffee/roast? Personal preferences? Anything else?

No. Yes/Yes (but it's more complicated than that). Yes. Oh yeah (pump, water, grinder, barista skill, environment, etc etc).


Of course, to throw a spanner in the works... I think there are things as important as the HX/dual boiler decision like rotary/vibe, plumbed-in/reservoir, E61/saturated group, semi-auto/auto, style of pre-infusion....
And to make it all more confusing, my dream machine would be a dual-boiler (though a saturated group, external rotary pump, manual pre-infusion, plumbed-in, semi-auto one).

[Walter]

Thanks for the warm welcome Dan & Chris!

As I mentioned above I'm but an aspirant to the craft (or should I say lore? ) of coffeemaking and actually it was your articles ("How I ... learned to love Hxs" and the "Mia Cribsheet") that brought the next significant improvement to the quality - and even more so a certain consistency - of my shots (the first had been recognizing the importance of distributing and tamping and of machine cleanliness) and thus made me question my former opinion that a Dual-boiler must be the best choice, even for the ambitious Home-coffee-maker like myself.

While I was fully aware that Schomer (in his book) is addressing only commercial situations, my thinking kept going along the line: "What is the best solution for the professional must also be best solution for the Home-Barista". It was only later that I started to question this and thus to-date I find myself very much in agreement with what Bruce's contribution "Questioning Authority" points out.

Now, I still appreciate Schomer's efforts in the past to improve the quality of the coffee served in his coffeeshops (after all he has been a major trendsetter with this, IMO) but his statements often remind me more of dogmas than of working hypotheses.

And unfortunately I lack such a positive experience from the commercial machines I occasionally get a ristretto from. Everything I got served within the past two months seems mediocre at best, when I compare it to my coffee at home.

Which continues to illustrate the key points.
1 - the espresso machine is probably the least important of the 4Ms.
2 - espresso is fundamentally subjective and personal.

Agreed but still, it doesn't help me with my decision as to which machine I should upgrade. I mean my Butterfly is a neat machine, it makes quite good coffee and it's not really limiting the quality of my shots, but it is definitely not the machine I'll be happy with for - say - the next decade.

To cut the long story short: Which produces the better coffee? Slant-L or HX-hump? (And - yes, I know, the one with the better guy at the handle side of the portafilter...).

You answered your own question.
Seriously.

But seriously... it depends. Assuming equal and very high skill it will depend on the coffee, your barista style (technique choices) and your personal taste in espresso.

Again, I don't argue, but that doesn't help me either. My skill is probably rather low, but I'm willing to learn and destined to improve. And - unfortunately - I won't get the opportunity to work for some time with any of the machines that come into consideration before making my choice. And I'd venture to say that very few aficionados, like myself, ever get a chance to lay a hand on one of these fancy machines like a Mirage or a Mistral, let alone pull a shot from it and see whether or not it tastes very different from the coffee they make at home...

This all means that I - like many others - will probably have to make my decision based on theoretical considerations rather than practical experience.

Of course, to throw a spanner in the works... I think there are things as important as the HX/dual boiler decision like rotary/vibe, plumbed-in/reservoir, E61/saturated group, semi-auto/auto, style of pre-infusion....

As for the rest you mention, I have a much clearer "vision": rotary, plumbed-in (but not dependent on water pressure for boiler refill; which pretty much would rule out the Junior DT, I guess), wouldn't mind another E61 but would prefer manual pre-infusion, semi auto would suffice

And to make it all more confusing, my dream machine would be a dual-boiler (though a saturated group, external rotary pump, manual pre-infusion, plumbed-in, semi-auto one).

Now we're talking: Do you mean for home use? And if so, why dual boiler? Care to elaborate why your personal preference is a Dual-boiler rather than a HX?

Sorry for the longish post...

P.S. Dan, I shall be awaiting Abe's Brewtus review with bated breath

[malachi]

Why that set of attributes?
Well... I really want a saturated group, so that pretty much requires a dual boiler setup to be most effective.
If I had to rank the importance (to me) of the listed attributes they would go:

1) plumbed in
2) rotary pump
3) semi-auto
4) saturated group
5) manual pre-infusion
6) external pump
7) dual boiler

In other words, I'd be happy with a plumbed in, external rotary pump, semi-auto, manual pre-infusion HX machine but there would be some sacrifices in total quality due to the lack of a saturated group.

[lino]

This prompts a question (somewhat related):

Do the HX machines that are not E-61s (such as junior, pasquini, elektra,... it's a long list, no need to continue) have a thermosyphon, or just a "one path" HX thru the boiler to the group?

Chris, may I also ask, "Why your preference for an external pump?"

And finally, "What is manual pre infusion?" A setup where operator controls the pre-infuse time? Pressure? Both?

Thanks

lino

[malachi]

I would guess that each of the various other options has its own proprietery system, but you're going to have to ask the folks who have those machines I guess.

I prefer external pumps for two reasons. First - noise (particularly resonant and vibration). Second - ease of adjustment.

Manual pre-infusion would be operator controlled pre-infusion time. I, personally, prefer the LM GS style (or Synesso style) where this consists of an initial step that opens the solenoid but does not turn on the pump.

[Walter]

Thanks Chris, I think I understand.

But wishing for a saturated group doesn't leave one with many choices, does it?

I'm not really familiar with that league, but aside from the LM Linea, the Synesso Cyncra and the van der Westen's are there many other machines which have it? But neither one of those lot would be negotiable with this families ministra of finance, I'm afraid...

[malachi]

You could wait for the LM Home machine...
Or try to find one of the old LM GS1 machines...

I fear that the brand recognition of the E61 group has resulted in few home machines using the saturated group. This is too bad. There is a reason why so many high-end, modern commercial machines have gone to saturated groups....

[casper]

My skill is probably rather low, but I'm willing to learn and destined to improve. And - unfortunately - I won't get the opportunity to work for some time with any of the machines that come into consideration before making my choice

and

But wishing for a saturated group doesn't leave one with many choices, does it?

I'd be bit careful, it sounds like *maybe* you're waiting for a machine which really might make you coffee worse (tricky to use properly) or maybe, since it doesn't exist (at your price range), a machine that you'll never get.

I feel Chris's top ten equipment features list is very personal. (Rotary pumps for instance are #2 on his list, is largely a noise issue for most people.) Anyway full respect to the list, I just don't think you should apply it to you without a lot of thought.

For me when Schomer talks about Dual-boiler temperature stability, I think he's dead on. Schomer's endorsement of a specific dual-boiler machine as "the best machine for the home user" supports the idea that he feels this is important for home users too. Yeah it's good to challenge authority..sure..but that includes some of the regular HB and CG posters too.

What is a machine? - an overly expensive water delivery device - controlling, amount, pressure, temp (and x-section - but that's fixed). [note to flamers: yeah it's an engineering marvel, it's a work of art...whatever]

I support thinking about the ideal machine being one that would remove any difficultly in controlling those variables to a noticeable level in the cup. (noticeable as is "for real" double blind with a panel noticeable)

Assuming you've got great water, beans, grind, pressure, distribution, etc. etc. and that temperature accuracy is a huge factor. Dialing in a consistent grind/temperature setting for a particular roast is, for me, huge, at the cafe or at home. HX machines frankly are not so friendly in this regard. This link is a well written description of the issue. Wouldn't HX owners would all be happier if they didn't have to surf? Surfing right takes some concentration to hone and while you're playing with that (if you're doing things right) it means that you aren't getting to improve your knowledge by playing with the other variables. It also means that once you've got it down, it's still another part of the dance you have to pay attention to or it will go wrong..

Of course maybe having it be extra-challenging is part of the fun for some people? Maybe the HX hump profiles are better than LM's slant...or maybe the emperor has no clothes.

Just an opinion. Buy what will make you happy.

[malachi]

I feel Chris's top ten equipment features list is very personal. (Rotary pumps for instance are #2 on his list, is largely a noise issue for most people.) Anyway full respect to the list, I just don't think you should apply it to you without a lot of thought.

Oh.. it's very personal. Absolutely.

But, that being said, for me the rotary pump is not about noise (okay, so noise is a tertiary factor, but you get the idea). For me it's about:
- cup quality (and clarity), and
- reliability and adjustability.

Wouldn't HX owners would all be happier if they didn't have to surf? Surfing right takes some concentration to hone and while you're playing with that (if you're doing things right) it means that you aren't getting to improve your knowledge by playing with the other variables. It also means that once you've got it down, it's still another part of the dance you have to pay attention to or it will go wrong..

I would disagree with this statement.
There are pros and cons of the surf issue.
The big pro is that it allows you to easily and quickly experiment with different brew temps and temp profiles for a single espresso. Doing so with a dual boiler machine is far harder and more time consuming. This is a not insignificant issue. It's one thing if you are always using one single espresso and know how you like it, but if you're using different coffees and trying to get to a better understanding of those coffee... temp surfing can then have its advantages.

I also would dispute that having to pay attention to your temp surfing means you cannot pay attention to other things. You have to be mindful of each thing as you do it and not when you don't. Adding one more thing to the chain increases your odds of screwing up - but doesn't result in you actually paying less attention to other attributes (and shouldn't result in you developing less understanding).

Of course maybe having it be extra-challenging is part of the fun for some people? Maybe the HX hump profiles are better than LM's slant...or maybe the emperor has no clothes.

For some coffees especially when combined with some barista techniques, the declining brew temp profile does, in fact, result in better coffee (to my taste). Of course, for me these are the rare exceptions to the rule.

That being said... sooner or later people will learn/accept that you can nearly exactly mimic the brew temp profile of a Linea on an HX machine. Dan has some great charts covering this in his article on HX machines.

This, in fact, is part of the one advantage of the HX machine - flexibility of brew temp and temp profile.

You have to pay for this with additional required barista skill. For a skilled barista, however, it seems like it would be a good trade-off.


Both are good.

[casper]

But, that being said, for me the rotary pump is not about noise

ok, I really do understand and believe that you find there is a noticeable difference in clarity between the two (without an accumulation tank or some other buffer for the vibe). Ok. But I find it very hard to think that most people, even mortal aficionados would would notice this as a standout factor in quality given all the other variables.

[As an aside: If it's clarity you're after don't you think you get the best in coffee (ie. most range, aroma, clarity and distinction) from normal hot water over grounds brewing..not espresso?? ]

The big pro [of HX machines] is that it allows you to easily and quickly experiment with different brew temps and temp profiles for a single espresso. Doing so with a dual boiler machine is far harder and more time consuming.

Wellllllll... I've always liked your point about being able to quickly try different temps.. (I take it to mean that you more or less set the boiler for a highish point and surf down?? Actually what are all the HX tricks here??)

But c'mon..it's not "far harder" for *most people* than a dual boiler with a visible temp control and monitor. I think you should get some sort of trophy if you could say take your HX machine and say I want this pull to be at 198 and this other one at 202 and hit it more accurately than someone that would push an up or down button on something like a Brewtus. Not that it can't be done, but you know...you were the guy complaining about intra-shot stability on HX, so there are hurdles to overcome, that's all I'm trying to say.

I also would dispute that having to pay attention to your temp surfing means you cannot pay attention to other things.

Sure, good point. But whatever time to do it (accurately) for someone with my limited capacities is gonna take away from something else. If you can remove one distraction, all the better.

Both are good

Yeah, exactly.
Make coffee. Mmmmmm.

[Walter]

I'd be bit careful, it sounds like *maybe* you're waiting for a machine which really might make you coffee worse (tricky to use properly) or maybe, since it doesn't exist (at your price range), a machine that you'll never get.

A brief tale: At the age of 35 I decided to learn playing classical guitar, without having so much as played one single chord on a guitar or any other instrument ever before. I bought me a 200$ guitar and started practicing. My progress was as slow as expected, but at a certain point I made a crazy decision: to buy me a better guitar. I bought me a 4000$ guitar which is rather unforgiving when played lazily, but produces a wonderful sound when played properly. Within a few months I made greater progress than in some 3 years before. The guitar simply forced me to do it right or not at all. Now I'm still nowhere close to Pepe Romero or Manuel Barrueco, but I enjoy myself every time I listen to my Kohno and my wife also tells me I play wonderful (she really must love me dearly to say something like this ). After more than a decade I couldn't be any happier with a classical guitar like my Kohno. Currently I am looking for an espresso-machine like that. One that simply forces me to pay attention and helps me developing my skills. Crazy, I know...

Now I'm not the kind of guy to lean back and ask from others to tell me what to do or what to buy, but I'm willing to listen to good counsel. And the reason why I am bugging skilled baristi with my questions is simply this: I have no chance of playing with this or that machine for a given time. I will have to make my decision based on the information I gather plus the experiences I make on my own current machine.

I feel Chris's top ten equipment features list is very personal. (Rotary pumps for instance are #2 on his list, is largely a noise issue for most people.) Anyway full respect to the list, I just don't think you should apply it to you without a lot of thought.

I chose a rotary for my next machine not because it is on any list, but because I am unhappy with the vibe/tank situation of my current machine and I also feel it makes it harder to pull consistently good shots with the E61 (and yes I know of the Junior comparison of Ken Fox and Jim Schulman).

For me when Schomer talks about Dual-boiler temperature stability, I think he's dead on. Schomer's endorsement of a specific dual-boiler machine as "the best machine for the home user" supports the idea that he feels this is important for home users too. Yeah it's good to challenge authority..sure..but that includes some of the regular HB and CG posters too.

I'm not challenging authorities per se or just for the fun of doing it. But I also don't buy anything just because an authority says so. It must make sense to me and/or be congruent to my own experiences. And I also consider the possible motives behind statements of authorities. And if I already knew what is best for a home aficionado like myself, I wouldn't bother asking questions here.

Temperature stability can be a good thing insofar as it prevents the shot from being bitter or sour, but - I am not sure Schomer's right when he says his roast e.g. tastes best when extracted at exactly 203.5F. What if his roast yielded even better coffee with a HX-hump temperature profile? Having been a learned chemist in one of my former lives, I should like to think that extraction of a complex mixture of flavours from a roasted bean is more likely to happen with a certain bandwidth of temperature, than when the temperature is stable to - say - 1/10 of a degree.

I support thinking about the ideal machine being one that would remove any difficultly in controlling those variables to a noticeable level in the cup. (noticeable as is "for real" double blind with a panel noticeable)

The ideal machine for me would be the one that enables me to get the best out of my beans and doesn't limit me. And I'm willing to do temperature surfing - just like almost anything short of some rain-dance accompanied by certain prayers in front of the machine - if if I am rewarded with a better coffee. I would mind it only if it were a waste of time and nothing to gain.

Of course maybe having it be extra-challenging is part of the fun for some people? Maybe the HX hump profiles are better than LM's slant...or maybe the emperor has no clothes.

I'm not looking for an extra challenge. Not if there's nothing to gain. But somehow I don't like the idea I could realize at a certain point in the distant future, that I have missed the better for the good I have had, due to my own laziness...

Just an opinion. Buy what will make you happy.

Thanks for that, now, if I only knew what will make me happy....

Cheers

[malachi]

Temperature stability can be a good thing insofar as it prevents the shot from being bitter or sour, but - I am not sure Schomer's right when he says his roast e.g. tastes best when extracted at exactly 203.5F. What if his roast yielded even better coffee with a HX-hump temperature profile?

Actually, his particular blend really does taste best with a very flat and very stable brew temp.
When there is inter-shot instability you tend to get the periodic very sour shot.
When there is intra-shot instability, you see a significant decline in sweetness and caramel in the finish and a significant increase in the "wet cardboard" note you can get from Malabar.

I think this is an excellent example of how the relationship between bean choice, roast choice, blend choice, machine choice, drink style choice and barista technique choice can create a closed loop type system for a roaster retailer. In the end, the results can become so interdependent that they lose all relevance to other people.

[casper]

I bought me a 4000$ guitar which is rather unforgiving when played lazily, but produces a wonderful sound when played properly. Within a few months I made greater progress than in some 3 years before. The guitar simply forced me to do it right or not at all.

Well the analogy of using something like a professional device to hone your craft is good. As you know the best commercial quality machines are double boiler machines which are a lot less finicky in practice (albeit after what could be a painful fixing/tuning stage) than these home machines.

Happiness? Maybe you ought to really seriously consider Chris's used-LM suggestions, in this case and steer even further away from HX.

[Walter]

As you know the best commercial quality machines are double boiler machines which are a lot less finicky in practice (albeit after what could be a painful fixing/tuning stage) than these home machines.

Happiness? Maybe you ought to really seriously consider Chris's used-LM suggestions, in this case and steer even further away from HX.

Well, there aren't many 2-, 3- or 4-group commercial HX machines out there I suppose? Thus that statement can be somewhat misleading in various ways, since the environment and the context are quite different for the home-user (as I mentioned in a previous post) than in a commercial situation. At home I probably won't ever pull a hundred shots in a row, but I often use half a dozen different roasts a week, and different roasts for Cappu/Latte and for Espresso most of the time. A closed loop system - as Chris mentions it above - is nothing I would wish for at home.

A used LM GS1 would sure be an interesting thing, something I'd be willing to give at least a try for some time, but those are hard to come by in our neck of the woods.