Why are HX espresso machines so popular?

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#1: Post by HeyMrBassman »


I think I'm up to upgrading my espresso gear.

At this moment I own a Saeco Aroma and use it with an non-pressurized portafilter.

My interest goes to an E-61-equipped machine.

But what I don't understand is that HX-machines seem to be the standard.
The E-61 head is all about temperature stability where you need to give a HX-machine a cooling flush to get it at the right temperature. This makes no sense to me.

When I buy myself a new machine , I don't want to still need to bother about the right temperature.

So why is it that the HX seems to be the standard for the better equipped home barista?

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#2: Post by jesawdy »

Hello and welcome to HB.

The E61-based machines are great, and while they help temperature stability with 8 lbs of brass, the E61's patents claim to fame is for preinfusion.

First, read Dan's HX Love article and the other recommended reading. The cooling flush isn't as hard to learn as reading these forums may lead you to believe, it is A LOT easier than temp surfing a single boiler machine like Silvia, et al. The reason the HX is more prevalent is for building milk-based drinks and maybe (just maybe) for hitting different brew temps based on shorter or longer flushes. A double boiler might be the way to go, but at considerably more cost and less choice.

Check out the current Vibiemme Domobar Super bench review, it looks to be very consistent and stable given some of Dave's recent temperature plots.

Also, check out the QuickMill Alexia bench review that is a single boiler (non HX) E61-design with available PID control.
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#3: Post by TimEggers »

Hello and welcome.

Recently (about 5 months ago) I went from a single dual use boiler Gaggia Coffee to the HX Quickmill Anita and it was like night and day. First every espresso machine is going to require some degree of cooling/temperature adjusting flush pre-shot. Its not a big deal at all and on Anita its super easy.

I've also come to appreciate the HX advantage for straight shot pulling. Yes HX are touted for steaming and the Anita is great for that, but straight shots are easier and better on the HX then on my old Gaggia. The e61 is also definitely the way to go. After having my HX for this length of time I wonder how I ever did it on a non-HX machine.

In my opinion HX (or dual boiler) is the way to go if you are making milk based drinks and HX is also beneficial for the straight shot drinker (then you wont have to worry about friends/family wanting drinks).
Tim Eggers

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#4: Post by Randy G. »

I will add my personal experience- For over 6 years I used a Rancilio Silvia- a superior machine, IMO, to the Saeco you have. For the last three or fours years my Silvia has been PID'd, first with a dual setpoint unit and later with an MLG kit. In all that time I have been home roasting. I now have the Vibiemme Domobar Super.

Remember that the PID added to a machine does not change the design of the machine, and if designed poorly and because of that mixes cold water with the hot in the boiler when brewing it still will do the same after adding the PID. The PID does overcome the problem with machines that are equipped with click thermostats which have a very wide deadband, and the PID gives easy adjustability, but a poor design that does not give thermal stability on its own will remain so after adding a PID.

An obvious benefit of going to a HX machine is that it affords the ability to steam and brew not only consecutively but concurrently. Have friends over? Pull two singles using the double basket, and while that is going on stretch some milk. If you are well organized you can make two cappas in about two minutes or a bit less.

HX machines have larger boilers than single boiler machines. In most all cases, much larger. A larger mass of water means greater temperature stability. It also gives more room and stored heat energy for steam.

The E-61 design is found on a lot of machines because it works. it works quite well. How well? It depends on a lot of other factors. If you look HERE at the review of the Vibiemme Domobar Super you will see Dave Stephens's graph of consecutive shots which is a most impressive demonstration of what a quality machine can do:

Read the article, not so much to sell you on that machine but to demonstrate the stability and shot-to-shot performance of a well-designed machine.

The espresso? It was superior right away and as I become more accustomed to the machine it gets better. Be sure to budget for a high-quality grinder as well. Something with infinite (stepless) adjustment will help get the best out of any machine. That should be the initial investment. And of course, a source of fresh coffee- silk purses and sow's ears and such....

if you want to avoid all the hassle and details involved with temperature stability, maybe a La Marzocco GS-3 is a better choice....? :wink:
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#5: Post by takeshi »

jesawdy wrote:The cooling flush isn't as hard to learn as reading these forums may lead you to believe, it is A LOT easier than temp surfing a single boiler machhine like Silvia, et al.
Precisely -- the HX machines are an ideal compromise for many between the single boiler and double boiler machines. Just keep in mind that the method used to heat the water doesn't tell you everything about a machine's temperature-related performance.

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#6: Post by HB »

HeyMrBassman wrote:But what I don't understand is that HX-machines seem to be the standard.
The E-61 head is all about temperature stability where you need to give a HX-machine a cooling flush to get it at the right temperature. This makes no sense to me.
It's true, figuring out flushing regimes for HX brew temperature management does increase the barista's learning curve. Someday some enterprising espresso equipment vendor is going to offer Eric's E61 thermocouple adapter or E61 thermometer adapter out of the box, thereby reducing articles like HX Love to interesting historical footnotes. In the meantime, E61 HX espresso machines earn their reputation because they're a good compromise on many factors (price, simultaneous brew/steam, reliability/maintenance, capacity).

It's interesting to note that double boilers are not as common overseas as in the US. I believe that's because so many Americans love "big gulp" lattes. Churning out dozens of 20 ounce "venti" lattes requires some serious steaming capacity. I don't know if it's really true, but Starbucks lore has it that La Marzocco got the contract not on the merits of their temperature stability, but their machines' boundless steam output.
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#7: Post by boar_d_laze »

Why are HX machines so popular?
Not to answer a question with a question but, "compared to what?"

If I read your post correctly you're asking "Why, after a certain price point, does the HX design drive the "switch to steam" design out of the market?" The answer is contained in the question, and Dan got it right away. The answer is steam. Instant steam in (small) commercially viable quantities. No back and forth between brew and steam. No two minute wait.

If you look at ad copy for some of the first HXs on the popular market, like the Pasquini Livia 90, you'll see that the copy writers set great store to the machine's ability to brew and steam simultaneously. There's also a certain amount of snob appeal in play. As the popularity of espresso spread in the US, you actually saw prosumer HX machines in small restaurants and bars (still do, too!), they seemed more professional, and hence more desirable. Do I sound disapproving? I don't mean to. That's part of my decision making process as well. When you're spending more than $1500 on a glorified coffee pot it's nice to have some validation from the big boys.

Double boiler machines, fairly new on the market, start at close to $2K, go north from there, and solve the steam problem more elegantly than HXs. The design also promises (and I stress the word promises) to reduce some of the problems with inconvenient temperature control. But they're expensive, and except for the Reneka, which is poorly distributed in the US, haven't had time to develop a following yet.
[Well paraphrase really.] What's up with the E-61?
The E-61 group was originally designed by Faema for commercial use. Driven hard, it's got a great thermal stability. Because of mass and design, you can bring it back to appropriate temp quickly after a resting period, and the pre-infusion feature is a wonderful thing. The kind of temperature accuracy that the gentlepeople of this forum talk about was unknown until fairly recently. The E-61 wasn't designed to hit brew targets with 1/2 deg C accuracy. That it can, even though requiring an elaborate "water dance" or a humongous boiler, testifies to the strength of the design. [Can I get an Amen?]

Other important pre-purchase considerations besides the group include boiler size, thermal mass, pump type, quality of other components like the pressure stat, availability of parts and service, etc. Things bing what they are, we're going to have to add energy efficiency to the list.

Back to the group, there are other designs which perform as well as the E-61.


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#8: Post by RapidCoffee »

boar_d_laze wrote:Double boiler machines, fairly new on the market, start at close to $2K, go north from there, and solve the steam problem more elegantly than HXs.
Not to quibble, but I consider the single boiler heat exchanger to be a very elegant solution to the problem of delivering both water for brewing and steam for frothing. As a software engineer, I would call the double boiler more of a brute force solution, not an elegant one. There's nothing wrong with brute force, as long as you have the resources for it.

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#9: Post by mrgnomer »

Much of the e61 group HX popularity, I imagine, is availability as well. The next step up from a single boiler thermostat control price wise and quality wise is either an HX or double boiler. There's only a few double boilers designed for home use I can think of. There are many more HX's and for the same quality of machine they're less expensive than the double boilers.

From what I've seen the HX design is pretty common to all. Designs differ with regards to flow restrictors, internal plumbing and probably in other ways I don't know but the major parts are common to all and stock. Most HX's are e61 groups. The group has been around since 1961 and it's tried and true. A stock part that not's particular to any one machine as far as I know. So for servicing not only are all HX's similar the parts are common and widely available making it easier and less expensive. You can maintain and service one yourself if you're reasonably handy.

For the price you're getting a good machine with an e61 group HX, I think. Temperature stability is very good, flushing is easy and very flexible for temperature control, preinfusion offers easier and more consistent extraction (whether the espresso is better than no preinfusion is undetermined, I think), brew pressure and boiler pressure/temp is adjustable, parts are robust and commercial grade... I upgraded from a Silvia to a Vetrano in less than a year and since the upgrade I've got no regrets nor a desire to upgrade further.
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#10: Post by edna713 »

I do not know WHY stock HX machines are popular. IMHO, an HX is optimized to make steam and VERY hot water w/ coffee as an afterthought.

It monitors boiler pressure! NOT temp. thus one COULD infer that it is basically a steam generator.

Ah, the flushing! the guess work and retraining, the sink shots, etc. etc. the constant refilling of the water tank -- if not plumbed in that is. The constant emptying of the drain tray -- if not plumbed in. The LOUD clicking of the 'high-end' Sirai pressure stat.

(If clicking every 20 seconds or so at idle bothers you or your S.O. -- beware!)

The energy waste, and on and on.

I owned a superb, brand new machine -- made in California -- and despised it.

Could not wait to unload it.

If one cannot afford a 'pid' HX, get a smaller machine and prep your milk, etc.
when you want it with a simple milk frother appliance = $75.00