Who is Kees van der Westen?

Factory visit 1/11/2011

A rare picture of Kees van der Westen

A visit to the Dutch equivalent of Santa Claus for good baristas in his hometown of Eindhoven.

First, I have a confession: I initially saw the Kees’ machines as equipment that was style over substance. Being suspicious of tight jeans and periwinkles, I have always preferred practical clothing and practical equipment. I’m more of a Linea or a Cyncra kind of a guy, machines that only need a set of tank tracks and a turret to be useful to the Blues and Royals. I had seen the Mistral and thought it looked a thing of beauty, but, I assumed, in a botoxed-bimbo-I-look-like-fun-until-I-open-my-mouth kind of way. It looked too pretty to be able to make serious coffee; I suspected it to be vulnerable to break-down and sudden faints.

It wasn’t until I was at a Cafe Culture fair in 2011 that I saw one of Kees’ machines in the metal. She winked at me. Many machines can wink. Usually I ignore them, but in this case I would have been rude to ignore her: it was immediately apparent that the Mirage is no cheap tart. After a few gentle minutes of pushing the buttons of Mirage Veloce and flexing the levers of her cousin, Mirage Idrocompresso, I was smitten. It was like walking up to a gorgeous woman expecting to be disappointed the moment she starts to talk and finding instead a beautiful woman that has read all the books, likes climbing mountains and clips her fingernails short. The machine makes coffee as beautifully as it looks. That it is also a work of art is due to its creation by a craftsman. And that craftsman was, reluctantly, there.

Kees likes attending coffee fairs like Sam Harris likes jihadists. Kees seems reluctant to step into the limelight and mostly lets his equipment speak for itself. That surprised me coming from a man whose brand is his name. I asked him about this. It was some advice he received while at design school, most successful designers are their brands – difficult for a man who doesn’t like his picture being taken. He constantly seems to evade the rockstar status he endures in the coffee world, however, the passion and the style of the man come through in his work and this is enough to ensure that there is always a waiting list for his machines.

Prototype Spirit

Prototype Spirit

Kees van der Westen machines are at the knife-edge of technology, but they’re at the duller edge of the blade. The multi-boiler PID model, Spirit, started commercial production in early 2012, just over seven years after Synesso produced the PID Cyncra. For such a lovingly crafted machine it was a rather reluctant engineer who produced it. He believes that the heat-exchanger is a more elegant solution than a multi-boiler and that manufacturers would do better to develop heat-exchange technology. However, the market demanded PID and a good businessman sells what the customer wants. Kees’ tardiness is good business sense. The bigger boys and the risk-takers develop the new technology and, once the trend is confirmed, Kees thinks about it for a few years and then crafts a machine that incorporates all the best elements of the leaders – but does so with improvements and  panache. He hasn’t started working on a pressure-profiling machine or scales in the drip tray yet, but he’s thinking about it.

I went to visit Kees because I now have a few of his machines and wanted to be sure that we maintained them properly. I had hoped for a machine to play with under the occasional eye of a passing technician. What I got was an excitable Dutchman for a day. There are cases where style and substance come together and when they do they strike like a thunderbolt. Kees turned up in a 1964 Thunderbird. Close enough.
His factory is set out in a very neat and orderly manner, as one’d expect from Northern European manufacturing. I was instantly envious of the order and supplies. Not the kind of respect of a peer visiting a fellow peer’s abode, but the slobbering envy of the die-hard Apple fan with last year’s model. Yet it’s got touches of eccentricity like the pinball machine at the top of the stairs and the Faema stuck to a wall with the sign saying ‘ARTWORK AHEAD’. It’s the same solid engineering, attention to detail and occasional quirkiness that I love about his machines.
The day was divided into three: session one lectures throughout the whole morning, session two dirty hands, three; pilfering. Kees feels it is important to understand everything that was ever anything to do about espresso. The lectures were part a history of Faema, part theory of thermodynamics and part practical application. Kees has an obsession with old Faema espresso machines.

I shall restrict the history of Faema to the E61 group head. The E61 group head changed espresso machines like the jet changed aircraft; it left pre-1961 espresso machines behind in a vapour trail. The ‘E’, by the way, stands for the solar eclipse of that year. The E61 brought in three critical aspects to the group head: Thermosyphon heating circuit, passive pre-infusion and a massive 4kg of brass. Temperature repeatability during brewing is extremely important for consistency. The temperature doesn’t have to remain the same throughout the pour for consistency, rather the temperature needs to be the same at any point during every pour. Both the thermosyphon circuit and the mass of brass ensure good stability.

Warning: what follows could be boring for those unfamiliar with the joys of WD-40 and number 8 wire.

In a heat-exchange[HX] espresso machine, a boiler heats water to a temperature controlled by the pressurestat (aka pressostat). This boiler provides both the water for the hot water output for long blacks, tea etc and the steam for the steam wand. The group heads are supplied by fresh, cold water from the water supply that travels in a pipe through the boiler, but not into it. The cold water pipe actually travels several centimetres into a wider pipe inside the main boiler. This wider pipe is effectively an internal boiler inside the main boiler. This method of heating is a very efficient solution to the problem of supplying steam, water over 100ºC, and brewing water, around 90ºC-96ºC using one boiler.

diagram of heat-exchange espresso machine

The mass of hot water in the main boiler rapidly heats the water in the internal boiler as shown in the diagram above. The pipe exits the main boiler at the top and takes the hot water to the top of a chamber in the group head. Another pipe exits the bottom of this chamber and travels back to the bottom of the internal boiler. This is the thermosyphon circuit. The water within the closed circuit is constantly moving due to being heated within the boiler and cooling as it heats air at the group head and, to a lesser extent, from the piping.
Although Faema was once a beacon for espresso technology, the light of their light faded over time and now casts a hazy glow next to the illumination of the likes of Synesso, Slayer and La Marzocco.

Top-end espresso machine manufacturers have tended to move away from heat-exchange and the thermosyphon circuit, relying instead on dual or multi-boiler machines with saturated group heads (this simply means that the group head is directly connected to a boiler and the heating is provided by the thermosyphon flow of water from the boiler through the open neck to the group head). This was pioneered by La Marzocco, who used one large steam boiler and a second PID controlled boiler that produced a very stable temperature at the group head.

diagram of dual-boiler espresso machine

This was simply termed “dual boiler technology”. Many machines now have separate boilers for each group head. The better machines still tend to have saturated heads.

So that was the end of heat exchangers for use in coffee. It’s a pity because it is such an elegant and energy efficient solution to the engineering problem of providing water at two different temperatures. Moreover, I am still undecided about whether espresso coffee made with ‘fresh’ water tastes different to espresso coffee made with ‘stale’ water – in blind tests I can’t taste the difference. Some people claim a preference for fresh water, in which case, the heat exchange system has an advantage over the double boiler and multi-boiler systems. If only someone still believed in the system enough to improve it.

Not a day dream: a Mirage.

Back to Kees who believed enough in the system to improve on it. Several things make these machines the best HX machines in the world: no need for a cooling flush, Proportional Integral Derivative [PID] for the main boiler, adjustable restrictors for each group head, exceptional reliability and it’s also pretty sexy.

Redundant cooling flush

One of the most annoying things about HX machines is the need to do a cooling flush. Whenever the HX machine is at rest, the hot water in the thermosyphon circuit rises to the top as seen in the left hand diagram below.

Diagram of a heat-exchange espresso machine showing the reasons for a cooling flush

Heat exchange in espresso machine. Left: at rest with hot water at highest point; Middle: beginning of cooling flush; Right: flush until more stable temperatures.

When we engage the pump, the initial water is really hot like the middle diagram and if you wait a bit, it’ll become cooler as in the right hand diagram. The trick here is that the first shot pulled after a rest is likely to be far too hot and we need to flush the initial ‘angry’ water out to get over the temperature hump and into more stable temperatures on the other side. All subsequent shots don’t have the higher temperatures until, that is, there’s a lull in service for a few minutes and we’re back to having hotter water at the top of our system.

Graph showing variation in brew temperature a heat-exchange machine group head

The aim of the cooling flush is to get over the initial hump and into the more stable temperatures on the other side.


The Mirage gets over this issue with the simple addition of some extra piping after the group head, which means that most of the water for the initial brew comes from the cooler, lower return pipe. If you’re using the Mirage lever machine (Idrocompresso), there’s also the option of an electric flush to ensure that your brews are always the same temperature – a far better option than pulling down the lever for a quick flush.

PID in the main boiler

PID is a feedback system that, in this case, makes intelligent adjustments to the heating in order to get more stable temperatures. Why would you do that with a HX machine? Why not. I don’t know of any other HX machines that do have PID, but better temperature stability is always a good thing for consistency and it makes changing the brew temperature much quicker than having to dive into a hot machine and fiddle with a pressostat. Which leads me on to another thing…

Adjustable restrictors for each group head

One way to change the brew temperature in a HX machine is to increase the temperature of the water in the boiler. Adjusting the pressostat so that the water in the boiler is hotter, transfers more heat to the water passing through the boiler in the thermosyphon circuit, which changes your brew temperature. Aside from being tricky to do, it changes the temperatures in all heads and also will affect your steam pressure.

Adjustable restrictor on a heat-exchange machine

Adjustable restrictor

Kees gets around this issue by installing adjustable restrictors before the group head in the thermosyphon circuit. By further restricting the flow in the thermosyphon circuit, we slow the rate of heating to the group head. The group head is made of that large mass of brass and a cooler group head will cool the brew water as soon as it comes in contact. In reverse, if we open up the restrictor, we increase flow rate to the group head and this will heat or brew temperature. The side effect of this is that this will also change our flow-rate, so the system is not ideal, but much better than having no adjustable restrictor.

 Exceptional reliability

All machines have their issues, but some machines just work. The big difference between Kees and big manufacturers like La Marzocco and Nuova Simonelli is that Kees had six guys working with him and a 20 week lead time for his machines. Naturally, this is a problem for customers who often, foolishly, try to order their machine a month before opening. I asked Kees if he could speed things up and he said that he had been looking for a year, but hadn’t found anyone suited to the job yet. The advantage is that the guys I met were top blokes with a passion for what they were doing. Each of the machines is exceptionally well put together. That said, I have had many more issues with the Spirit, Kees’ multi-boiler, than I’ve had with the Mirages. However, I publicly challenge to a bare knuckle fight anyone who says that there is a better espresso machine than the Speedster.


So in answer to the questions ‘Who is Kees van der Westen?’ He’s an engineer who loves to experiment, he has very high standards in workmanship and integrity and is a great teacher. He also doesn’t like his picture being taken. Like this:

Kees foot

or this:Kees van der Westen instructing on the engineering principles of a heat-exchange lever machine - Mirage Idrocompresso and especially not this:


But the important thing is the attention to detail and technical excellence of his machines that make many other machines feel like they were made by Tonka. Are they the best machines in the world? No, or rather, it depends what you’re after. Slayer, Synesso and La Marzocco make excellent machines as well. Slayer machines are gorgeous and are great to play with, but they have had their multiple reliability issues that I’m assured are now fixed (but I’m still too wary). Synessos are great despite looking like my uncle Rangi designed them. La Marzoccos are mass made, despite being handmade, and suffer from build quality issues. I would happily work with any of the above – I have. But if I I have to choose a favourite espresso machine manufacturer, I would choose the one where nearly every time that I order a new machine it arrives with subtle new improvements, where I can install the machine and be reassured that it’ll take whatever is thrown at it for years with minimum maintenance and where the owner picks you up from the train station in a blue ’64 Thunderbird.


4 thoughts on “Who is Kees van der Westen?

  1. Great to read more about this technology and your thoughts on the pros and cons. Don’t La Spaziale also use HX technology in their machines? Would appreciate your thoughts on these..

    • Most espresso machines are HX probably because it’s the cheapest way to solve the Flat White problem. I’m not a huge fan of any La Spaziale machine that I’ve tried, but they may have good machines that I haven’t and I do find their small diameter groupheads are interesting.

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