The Best Heat Exchanger Espresso Machines

BY BORIS POVOLOTSKY - 2024-01-01T21:20:13.035Z

Greetings, fellow coffee enthusiasts and home baristas! As we enter the caffeinated realm of 2024, the quest for the perfect cup of espresso never ends. Today, we’re exploring a rather sensitive category of espresso machines, the heat exchangers! It’s a sensitive area because there’s always the question of whether one should bother buying a heat exchanger when there are plenty of dual boilers for various budget ranges. In this post, I’ll try to inform the best I can on who should buy a heat exchanger, what model specifically, and who should settle for a dual boiler.

Those seeking to join the great hobby of brewing espresso at home, or those interested in upgrading their single-boiler, will enjoy any of the HX machines I’ll review here today. Every machine listed here will provide the user the ability to brew and steam simultaneously, which is in my opinion, the number one reason to get a heat exchanger machine or a dual boiler in the first place. However, there’s a reason HX machines aren’t the ultimate treat and there are some major nuances that you must be aware of before buying one. Don’t worry, I’ll go over those and touch on whether or not it should concern YOU.

What Is A Heat Exchanger Espresso Machine?

Heat exchanger (HX) machines are essentially single boiler machines with a tube passing through the boiler which functions as a dampener, either cools down water if it’s too hot or raises its temperature if it’s too cool. It does so very quickly. You can read Dan’s love of HX for a more in-depth explanation. The HX machines are considered more manual and involve more guesswork as opposed to using a dual boiler with a PID, this isn’t to say it’s inferior, it’s just different. It can be more enjoyable to use an HX machine, but it sort of adds another variable to worry about, so you should consider this aspect of the heat exchanger machines.

If you’re into an experience that’ll involve hands-on experience, and don’t worry too much about perfect consistencies of brewing temperature, you’ll be very satisfied with a heat exchanger machine for good. 

Temperature Control in Heat Exchanger Machines

I’d like to yet again refer you to HB article on this topic. Additionally, I’ll try my best to summarize and simplify. The single boiler of the HX keeps the water at steam temperature, which is very hot and not suitable for making espresso, thus, we need to manipulate the temperature by performing a couple of simple steps.

Assuming the machine has warmed up for its recommended warm-up time before we make our shot of espresso, we’d need to cool down the water by flushing water from the group head, also called the HX cooling flush. As soon as you flush, you’ll hear boiling water sputtering out. When you do this, you waste the overheated water, while cool water goes back into the loop and gets reheated by the heat exchanger tube. For most HX machines, you’d need to perform this cooling flush and wait until the boiling water spills stop and the stream is constant.

Don’t pour too much water because you’ll end up with too cold water.

As soon as you’re done flushing, prepare your basket, and make your shot.

Let’s review a couple of heat exchanger machines that I’ve been reading and researching about and decided along the way that if I’d get a heat exchanger, it’d be one of those. Disclaimer, I did not own any of those machines, it’s based on pure research and conversation with owners.

Should you get a Heat Exchanger Espresso Machine with PID

Yes. No. It depends.

A PID on a heat exchanger espresso machine functions a little differently from what you’d expect. Why? I can think of two main reasons:

  1. The variance of numerous factors that impact brewing temperature renders the PID on a heat exchanger a little bit impractical. Merely adding a PID on an HX won’t promise precision and perfect consistency.

  2. The PID sets the temperature of the boiler, which is kept at steam temps (over 245F), therefore you do not control directly the brewing temperature. It might be useful for controlling the steam pressure, though.

Each and every heat exchanger with a PID will behave differently and you’ll have to learn your specific machine and adjust according to your requirements. You’d want different brewing temperature for different coffee roasts, for example, for lighter roasts you need to maintain a higher brewing temperature.

That being said, the PID provides a little convenience to the overall experience, thus it shouldn’t be dismissed easily. Bear in mind, a PID on a machine will probably cost more. If it gets high to the point it makes sense to get a dual boiler instead, then please, consider a dual boiler as well.

HX vs Dual Boiler

This is a very common question people often ask me before purchasing an espresso machine. Fortunately, the differences are quite easy to understand; however, the wide range of options can still complicate the decision and leave you stuck for hours reading endless amounts of blogs and forums.


Typically, a dual boiler will be more expensive than an HX. Entry-level dual boiler machines, such as the Lelit Elizabeth, come at a cost. Cheaper dual boiler machines will likely feature smaller boilers, involving cost-cutting decisions that might affect build quality. Take Elizabeth’s sister, the Mara X, which comes at a comparable price and is considered the top-of-the-line heat exchanger machine. Many prosumers still prefer the Elizabeth over the Mara X, simply because you get a featureful dual boiler machine from a reputable brand, but some still go with the Mara X, despite the possibility of getting a dual boiler.

Dual boilers are pricier because they have more internal parts, heating elements, and controls. They also provide a different experience compared to the HX machine. Usually, a dual boiler with a PID solves most of the guesswork for you, especially in terms of brewing temperature, leading us to the great topic of temperature management in HX machines.

Temperature Control

Heat exchangers usually involve more guesswork, whereas dual boilers are more straightforward with PIDs controlling each boiler separately. Whether or not you should be worried about temp control too much as a beginner is a question nobody can answer except yourself. If you simply want the same result most of the time with as few imprecisions as possible, then get a Decent or a decent dual boiler (sorry).

Lastly, dual boilers tend to be bigger and chunkier in size.

Lelit Mara X

If you’ve been reading my other purchasing advice articles, you’d be quite accustomed to seeing Mara X starring all over my blog, and for a good reason! Lelit 62 (mara) is designed in such a way that bypasses the traditional hx cooling flush requirement for most users. That’s right. Everything I wrote about the cooling flush isn’t necessary with the Lelit Mara X. Moreover, the Mara X comes at a very attractive price tag, which, in my opinion, puts it in the 1st place of my favorite heat exchangers for 2024.

The Mara X is a compact machine with a narrow look, it’s about 9” wide. Despite using a vibration pump, it’s considered quieter than most vibration-based machines by many users. There is a sort of PID control with 3 temperature positions: 0,1 and 2. The 0 position is for 89-91, position 1 is for 91-93, and position 2 is for 93-95, temperatures are in Celsius, and the machine’s default position is at 91-93c which is okay for medium roasts.

The Mara X features a traditional look with its E61 grouphead, so if you’re after the traditional look and want a rather simplistic machine (operationally speaking), then the Mara X is spot on for you. I truly believe that Mara is the best machine for most folks.

Who Should Not Buy This

If you’re after precision and want consistent temperature shot after shot, you should avoid this machine and look for something like the Elizabeth, or the Decent at much higher cost. The temperature fluctuates and doesn’t provide this perfection. On the other side, if you’re looking for a manual operation, such as a lever espresso machine, check out the La Pavoni. Now, that isn’t to say that the Mara X isn’t capable of producing great cups of coffee and extracting delicious flavors out of even light roasts.

Why The Mara X is the best heat exchanger machine…

  • Budget-friendly
  • Can avoid cooling flush with X mode
  • Compact, narrow footprint
  • 25-minute warm-up time
  • Steam and brew simultaneously
  • Traditional E61 design

If you want more technical details, and read more in-depth reviews, then check out this index page I have created for this machine.

ECM Mechanika Max

The Mechanika Max is the latest release from the German ECM brand. The Mechanika has a traditional E61 group head, it features a PID, and a smart display to let you know whether or not you need to flush. The ECM Mechanika is equipped with a rotary pump, a 1.9 L stainless steel boiler, and a 1600W heating element.

Designed with a built-in scheduler allowing two programmable times, the Mechanika minimizes the 35-45-minute warm-up time by using a smarter heating system with a PID. While HX machines inherently face challenges in temperature precision, the Mechanika includes a temperature probe inside the machine. It may not directly reflect the water temperature from the group head, but an “offset” setting in the menu compensates for fluctuations.

Noteworthy are the joystick controls for steam and water, providing a modern touch. The machine offers preinfusion options, including both active and passive methods. Active preinfusion, programmable through the menu, complements the mid-lever-position option, while passive preinfusion becomes possible when plumbing the machine for line-pressure preinfusion.

The Mechanika introduces three temperature modes influencing its heating process, along with a convenient button to boost steam heat-up during shot brewing. This machine stands out among traditional HX machines and even the Mara X in certain aspects. Users can opt for a temperature control mode, allowing operation without the need for a cooling flush.

However, the distinguishing features come at a significant cost – nearly twice that of comparable machines. While the Mara X offers a more budget-friendly option, the price difference becomes more pronounced in the U.S. market. For a similar budget, one might consider a dual-boiler machine like the Lelit Elizabeth, offering added versatility and potential savings for accessories. Despite the higher cost, the Mechanika presents important features for a Heat Exchanger, reminiscent of how the Nurri Leva addresses pain points in lever espresso machines.

Rocket Appartamento

The Rocket Appartamento used to be a popular choice for many home baristas, especially before the Mara X came out. It was often seen as an upgrade for those moving from a Gaggia Classic Pro to a heat exchanger machine. The Appartamento is a sturdy machine with a unique design and a traditional E61 group, but it takes a bit longer to reach the right temperature.

The machine has a copper boiler with a 1.8 L capacity, and combined with the large E61 group, it takes about 35-40 minutes to become temperature-stable. In comparison, the Lelit Mara X achieves this in about half the time, with only 20-25 minutes of warm-up. Unlike the Mara X, the Appartamento doesn’t have a PID but relies on a pressurestat that you can adjust for steam power and boiler temperature. Adjusting it involves opening the top case, which may be a bit more involved.

In terms of operation, the Appartamento, being a classic Heat Exchanger (HX) machine, requires flushing to remove boiling water and needs some recovery time between shots. While the Rocket Appartamento is aesthetically appealing, the Mara X is considered a more convenient choice for temperature control.

Although the Rocket is visually more attractive, the Mara X is not bad-looking either. Considering the Mara X is often priced more affordably in many countries, along with other differences, it becomes the more obvious choice between the two.

Ultimately, the Lelit Mara X is considered the winner, especially for those upgrading from a single boiler machine. However, if you already own an Appartamento and appreciate the E61 group and Rocket’s distinctive look, there might not be a compelling reason to switch to the Mara X. Frankly, I don’t think it would be a worthwhile decision to upgrade from such a machine to the abovementioned Mechanika Max either.

Profitec 500

I love Profitec. Perhaps, I am biased. I don’t care as long as the brand produces solid and high-quality espresso machines. The Profitec 500 is considerably more expensive than the Mara X, but it’ll feel much more sturdier and of a higher quality than the Mara. It has a slightly bigger boiler as well. There’s a PID version available for the Profitec 500, and again, whether or not you should buy a heat exchanger with a PID is debatable, consider the price. If the price gets very high, it might be worthwhile to save some money for a Lelit Bianca or a Profitec 600 and get yourself a proper dual boiler setup.I like the fact that Profitec keeps working and improving their machines, even though they mostly update machines aesthetically, after all, we do care about how our precious machines look, right?

Honestly, I probably would’ve passed on this machine and gotten the Mara X and saved the extra cash for accessories and whatnot, or, I’d spend a couple hundred more and get myself a dual boiler that I wouldn’t have to worry about upgraditis. Don’t get me wrong, the Profitec 500 is a great heat exchanger machine, there are many many folks around reddit, home-barista and other forums that are very happy with this machine and you really can’t go wrong buying it.

Wrapping Up

In conclusion, the Lelit Mara X emerges as a clear winner. However, despite all the great things I mentioned about the Mara X, you should perform your own research to supplement everything that might be missing. For instance, it’s a good idea to visit a User Experience thread on the forums for each machine and see what users brag or complain about. You can find out about common issues and see whether or not it’s something acceptable that you wouldn’t mind fixing yourself, or it’s a big no-no for you.

Every machine has some issues that are more or less common and you can see to what lengths users have gone through to fix some issues, add certain modifications, and so on. Some modifications of the Mara X include the fascinating data visualization mod, you should definitely check those out.

So, I hope this article was useful for you, whether it’s for gaining information on what is a heat exchanger espresso machine or a recommendation list with important takes and notes on several machines. Obviously, we didn’t go through all of the possible contenders out there, I only provided the machines that I think are worth your consideration. Good luck!

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