Why are HX espresso machines so popular?

[HeyMrBassman]

Hi,

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?

[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.

[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).

[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....?

[takeshi]

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.

[HB]

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.

[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.

Rich

[RapidCoffee]

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.

[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.

[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

dave

[keepitsimple]

IMHO, an HX is optimized to make steam and VERY hot water w/ coffee as an afterhought......

I share your views, having been in the same situation of owning a very well respected HX machine in the past.

I came to the conclusion that HX is probably a neat idea for commercial machines with large boilers which are in fairly constant use, but doesn't downsize well to the very much smaller boilers in the "prosumer" machines, and the relatively intermittent use they get in a domestic environment. A commercial machine with a big boiler will have steam to spare running at a lower temperature than is needed in the much smaller boilers in domestic machines. In addition, constant usage will keep the water flow through the HX's at a rate where overheating isn't going to be a problem. The combination of these 2 factors makes them much more easily usable than the situation home users are faced with.

Small HX machines are, of course, ideal for those who love to play around with flushes and practising their art of getting the temperature targetted to a fraction of a degree. I'm not sufficiently obsessive - see my username

I sold the HX machine, and bought a double boiler machine which is much much easier to use, and for me much more consistent in the end product it produces. It has electronic and adjustable temperature control of both boilers, insulated boilers, automatic or manual dosing, and is plumbed in and out.

I did toy with the idea of getting a good single boiler machine - Zaffiro type, and something like a silvia just to make steam. Decided that the space would be a problem...and aesthetics came into it a bit have to admit

Anyone who asks for my advice these days gets pointed towards a double boiler machine. It's a shame there are so few on the market, especially now the Reneka is no longer manufactured. If I had to buy again, I'd almost certainly get a La Spaziale S1 based on what's currently available.

[HB]

If one cannot afford a 'pid' HX, get a smaller machine and prep your milk, etc.

In the spirit of full disclosure, readers should be aware that Dave (edna713) is a vendor specializing in PID'd espresso equipment.

[Marshall]

I'm working on a theory that the demand for home HX machines is actually created by the mismatch of these machines with their home environments.

They sit idle for hours at a time, overheating. This makes their temperatures difficult to control, except for very experienced users. So, most owners wind up making bitter espresso with them, which they cannot enjoy, unless they drown it in foamed milk. HX machines are more efficient than single boilers for steaming milk, which leads the owners to believe they "need" an HX. Quod est demonstratum (or something like that). [Edit: corrected legal Latin to geometry Latin.]

On top of this they must also plumb in their water input and drain because of the long cooling flushes they require. Plumbing the input requires water treatment in most parts of the country, which adds more expense

That's my theory, and I'm sticking to it.

[perstare]

As I am relatively new to all of this and want to benefit from other people's experiences before I take my $ 2200 plunge,
I've been reading many of the topics and threads.

Specifically the confusion on HX machines is as follows: one of its salient features seems to be the ability to pull a shot
and froth/steam at the same time. However, a merchant on the internet suggests not to do this as it will adversely effect
the pressure or is it the temperature. Thus the confusion.

What is PID ?

Thanks.

[HB]

However, a merchant on the internet suggests not to do this as it will adversely effect the pressure or is it the temperature. Thus the confusion.

I assume the merchant refers to a potential brew temperature drop while steaming. I measured the difference awhile back and it was negligible, at least to mere mortals.

What is PID ?

Short answer as applied to espresso equipment: It's an electronic temperature controller. For the longer answer, see Good all round explanation of PID stuff.

BTW, lest you be led to believe that I'm a walking index given the speed with which I found this, it's actually in the FAQs and Favorites for this forum. The longer version of the site's "best of" is in the FAQs and Favorites Digest. Check it out.

[TimEggers]

Having used a vibe pump HX (that isn't plumbed in) I don't see the difficulties some describe. You flush a bit you pull the shot. I've had no problem making excellent espresso with my HX. I fill the tank at the beginning of each session and dump the drip tray at the end of the day.

I am of the opinion that an HX in the home can be a worthwhile tool for exceptional espresso or milk based drinks for almost anybody (hey if I can do it... ).

[jesawdy]

Specifically the confusion on HX machines is as follows: one of its salient features seems to be the ability to pull a shot and froth/steam at the same time. However, a merchant on the internet suggests not to do this as it will adversely effect the pressure or is it the temperature. Thus the confusion.

I have seen that stated as well. I suppose there are many home use machines that may not have what it takes to continuously steam while pulling a shot. I know this is one of the things stated about why the Fiorenzato Briccoleta requires a 20A outlet and uses a higher wattage element, because it can do this.

Truth be told, I wouldn't get hung up on this. You will likely be able to steam and pull at the same time (it may affect the shot temperature), but in practice you probably rarely would ever do this. You will however certainly be able to enjoy the convenience of steaming immedialty after (or prior to) pulling a shot.

What is PID ?

PID = Proportional Integral Derivative, it is a type of control that can be used for controlling process variables such as temperature. Search these forums for much more discussion. See Wikipedia for some background if you're interested, link.

[Marshall]

Having used a vibe pump HX (that isn't plumbed in) I don't see the difficulties some describe. You flush a bit you pull the shot. I've had no problem making excellent espresso with my HX. I fill the tank at the beginning of each session and dump the drip tray at the end of the day.

I think most users would consider unloading the warming tray, removing the tank (or filling a pitcher and carrying it over to the tank), filling the tank, replacing the warming tray and all the cups on it before each session to be a major nuisance. But, maybe I'm just lazy.

[HB]

I've had various types of espresso machines pass through our kitchen and the "nuisance factor" partially depends on the locale. For example, if the machine is located directly next to the sink, it's a minor inconvenience compared to when the sink is across the room (who hasn't done the full drip tray "challenge" walk?). Recently I'm testing the Quickmill Alexia, which isn't an HX and has a large driptray. I still refill the tank every other day, if only to keep the water fresh.

That said, I'm as lazy as the next guy and opted for a fully plumbed in unit. HX or not, I think it's worth the trouble.

[TimEggers]

I think most users would consider unloading the warming tray, removing the tank (or filling a pitcher and carrying it over to the tank), filling the tank, replacing the warming tray and all the cups on it before each session to be a major nuisance. But, maybe I'm just lazy.

Forgive me I simply felt compelled to point out that if push came to shove it's a manageable nuisance. I was forced to go pour over due to circumstances beyond my control so I suppose I have come to learn to live with what I must do to make espresso in my kitchen setup (not use the warming tray [preheat cups with cooling flush water], dump drip tray into sink and pour fresh water into tank via pitcher once a day). I do believe a plumbed in machine as you describe is the most convenient but if that's not an option one can get by as I do.