A pointer to the future of espresso machines

The Ascaso Steel Duo PID is a thermoblock espresso machine that sets new standards. It combines high temperature stability with a short heat-up phase while still maintaining relatively low power consumption for an espresso machine. The combination of these features left a lasting impression on our testers, Michel Aeschbacher (Swiss Vice-Barista Champion) and Benjamin Hohlmann (German Cup Tasters Champion).

The Ascaso Steel Duo PID was tested as part of our thermoblock test series. Following an extensive series of tests on heat exchanger espresso machines, we are publishing a new espresso machine review every week.

UPDATE: The Ascaso Steel Duo PID was updated in 2022. We have tested the espresso machine again and summarized the changes in a video and article. You can find the short blog post on the latest version of the Ascaso Steel Duo PID here.

First impressions of the Ascaso Steel Duo PID

The espresso machine aficionados at Kaffeemacher are all in a shared WhatsApp group. There, we share machine impressions, draw attention to outstanding espressos, or highlight interesting content. This is also where we summarize test results in short, concise words. Michel's comment after the first measurement of the Ascaso Steel Duo PID was simply "insane." Attached was the following screenshot of the 1st measurement of the Ascaso Steel Duo PID's temperature profile. Felix's reply: "that is actually pretty awesome.".

That really sums up much of what we will detail below. To start with: there are also quite a few things we wish were improved on the Ascaso Steel Duo PID. Nevertheless, in many respects, it is a sign of the directions in which future espresso machines might be heading. Namely, towards thermoblocks or smaller boilers, towards energy savings, and fast heat-up times. These are all really strong arguments for a home espresso machine.

Summary of strengths and weaknesses

Strengths

• Temperature consistency from shot to shot and across multiple extractions
• Heat-up speed (3 minutes)
• Energy consumption
• Espresso quality (can be improved with simple upgrades)
• High-quality portafilter with wooden handle
• Control (volumetric, display)
• Side water tank

Weaknesses

• Build quality, especially on the inside
• Milk frothing power
• Heating of the machine
• Design of the cup warming tray
• Accessories (tamper, baskets)

The thermoblock duo of the Ascaso Steel PID

Two thermoblocks give the Ascaso Steel Duo PID its name. One of these two thermoblocks brings the brewing water to temperature. The temperature of this block can be easily set using a PID controller via a display on the front of the espresso machine. A second thermoblock is responsible for preparing milk. In both cases, water is passed through a spiral-wound stainless steel tube located inside an aluminum block. The thermoblock responsible for the brew water sits directly above the portafilter, ensuring good preheating of the portafilter. Ascaso does this much better than other thermoblocks we have tested so far. Those often struggle with the portafilter being too cold. This automatically leads to a cooling of the brew temperature during extraction, as heat is lost to the portafilter. We were able to measure temperatures of 89 – 92 degrees in the portafilter of the Ascaso Steel Duo PID even at rest.

The heat-up time of the thermoblock duo on its own is not spectacular. Like all other thermoblocks, the machine signals readiness very quickly (after 3 minutes). The speed only becomes truly exciting because the Ascaso Steel Duo PID is then actually ready to operate – in the best sense of the word.

Temperature consistency – Catalan Champions League

In terms of brew temperature, Ascaso delivers what makes a thermoblock a virtually unbeatable technology for heating brew water for espresso: consistency at its finest. Both during the shot and from shot to shot, the Ascaso Steel Duo PID takes on any heat exchanger espresso machine we have looked at. The brew temperature glides along like a straight line, and the temperature fluctuation over 5 double shots in 5 minutes is merely one degree. That is Champions League quality from the company founded in Barcelona in 1962. And to stick with football examples: next to it, the further development of some boiler machines over the last few years seems as sluggish as European football when the Spanish national team and FC Barcelona under Pep Guardiola descended upon them with their innovative tiki-taka football between 2008 and 2012.

Now, it must be said: thermoblocks are of course nothing new when it comes to heating brew water. Drip coffee machines have been emitting the sound of thermoblock water since time immemorial. What is new, or newer, is that the temperature from the Ascaso Steel Duo PID's thermoblocks is delivered at exactly the temperature we desire, thanks to an intelligent temperature control system. A good espresso can be prepared at temperatures between 92 and 94 degrees (log file of the measurement).

Boiler versus thermoblock

There are few remaining arguments in favor of a boiler espresso machine for home espresso preparation when a thermoblock performs as the brew thermoblock of the Ascaso Steel Duo PID does. Boiler machines include single-boiler, heat exchanger, and dual-boiler espresso machines.

• The temperature is at least as constant as the temperature of the better heat exchanger espresso machines we have tested
• The machine is at full operating temperature within approx. 3 minutes (whereas heat exchanger espresso machines require 20 minutes or more)
• The machine has significantly lower energy consumption (see next point), even if you didn't turn it off, which is perfectly possible since it heats up again in a short time.
• Furthermore, water does not sit in a boiler. Fresh water is supplied for the preparation of the espresso.
• A lower tendency to scale is another argument in favor of a thermoblock.

Points in favor of a boiler:

• Better milk frothing performance, both in terms of power and the consistency of the steam output.
• Proven "workhorse" mentality in catering settings.

We can't think of many other arguments in favor of a boiler when a thermoblock performs as well as the Ascaso Steel Duo PID. Please help us out if you find any other points!

Energy consumption

We tested the consumption in kilowatt-hours after 5 minutes and then 5 subsequent espresso doppio extractions. For this, we used an adapter from MyStrom.ch. The measurement showed a consumption of 0.09 kWh.

After another two hours, we performed another extraction of a double espresso. Now the consumption was 0.28 kWh.

The second value can be compared with the consumption of the heat exchanger espresso machines. We also measured these after two hours. The lowest consumption was recorded by the Xenia Espresso with 0.48 kWh and the Bezzera BZ10 with 0.48 kWh. The lowest performing was the Bezzera Magica S with 0.72 kWh.

It should be noted here that because of the short heat-up time, the Ascaso Steel Duo PID could also have been turned off. Then the energy consumption value after two hours would have been even lower.

Workmanship of the machine

One of the biggest points of criticism regarding the machine is the workmanship. The exterior of the machine feels tinny, especially when you tap on the side panels or the cup tray. If you compare this with a stainless steel beast from the heat exchanger class in the same price range, then ECM, Rocket, and co. win the race.

However, the Ascaso Steel Duo PID counters with one of the most beautiful portafilters included in the standard delivery. A wooden handle is an upgrade for many other machines, but it's already included here. A look inside the machine is not for those who appreciate tidy cable management. Perhaps the tiki-taka tactic was at work here, but rather to the machine's detriment. Everything looks a bit untidy. We have received feedback from users of the Ascaso Steel Duo PID that screws were not properly tightened and cables were pinched. We couldn't confirm this ourselves, but we did find a plastic cover that had fallen off. Not serious, but a sign that the same care was not taken here as with the calibration of the machine.

The Ascaso Steel Duo PID is 27 cm wide, 31.5 cm deep, and 36 cm high. The water tank holds 2 liters and the machine weighs 15 kg.

From the outside, the Ascaso Steel Duo PID makes a good impression at first. But those who look closer will find unsightly side effects. The drip tray is actually made of plastic and only has a metal cover. The slope of the cup tray causes the cups to slide backward due to vibrations during extraction. Even if you place the cups apart at the beginning, they end up cuddling at the back of the tray by the end of the shot. The result is a cup-clinking orchestra that turns up the volume.

In our opinion, the cup warmer provides way too much temperature. We would advise disconnecting it at the internal connector. You don't need such warm cups. The machine itself provides enough waste heat, at least if it's on for a longer time. If you only have the machine in operation for short periods, then the heater makes sense, of course.

Espresso quality of the Ascaso Steel Duo PID

The barista is responsible for many steps on the way to the perfect espresso. Coffee-to-water ratio, the grind size, good preparation of the coffee in the portafilter, distribution, and tamping. Then follows the work of the espresso machine. What the Ascaso Steel Duo PID basically delivers here enables a perfect espresso. Constant brew temperature and constant pressure are the fundamental factors for a good result.

And so we also drank many good espressos (our Dreispitz-Espresso, to be precise), and yet we improved the quality with two small interventions. First, we swapped the shower screen of the Ascaso Steel Duo PID for the IMS Competition shower screen. This makes an incredible difference in distribution. The water is thus distributed very homogeneously over the entire coffee puck. Second, we replaced the baskets with these IMS baskets (size 24.5). Their holes reach closer to the edge than those of the small included baskets, which hold barely 15 grams. Furthermore, with a capacity of a good 19 grams, they allow for longer drinks to be brewed. This makes sense for both espresso and cappuccino.

We use several Ascaso Steel Duo PIDs in our academies and have subjected all of them to this basket upgrade. Then the machine can also be used very well with our tamper.

Milk frothing is not a core competency of the Ascaso Steel Duo PID

Anyone who mainly drinks milk-based beverages is probably not perfectly equipped with the Ascaso Steel Duo PID. This is because the milk foam performance cannot keep up with the frothing behavior of heat exchanger espresso machines in the same price range. The pressure generated by the second thermoblock is too low. You can froth a 600ml milk pitcher with the Ascaso Steel Duo PID, but it really requires a lot of practice and experience to stretch and roll the milk at the same time (see also our Latte Art Tutorial on our YouTube channel).

We recommend opting for the small 350ml milk pitcher. With some practice, the milk foam will then turn out well. However, if cappuccino and the like play a major role in your choice of beverages, then we would rather advise going for a heat exchanger espresso machine.

Conclusion on the Ascaso Steel Duo PID

The Ascaso Steel Duo PID is an excellent espresso machine in many respects. The temperature consistency stands out above all else. It shows what is possible in terms of thermoblocks. With such consistency, even across multiple shots, the machine is a pointer towards possible developments in the field of home espresso machines.

Many classic espresso machine manufacturers continue to rely on large boilers that must be brought up to temperature and maintained. In theory, these are then constant, although our heat exchanger test also showed that this does not apply to all machines. What is certain, however, is that for a few espressos a day, a lot of water has to be heated. The thermoblock proves that there are smarter solutions for this. If manufacturers like Ascaso or Decent in a higher price segment now prove that the temperature can also be perfectly set with thermoblocks, then we are curious to see how this will inspire the market. We are looking forward to seeing what might happen in this area over the next few years.

Addendum: Availability and calibration

We do not sell the Ascaso Steel Duo PID in Germany.

We have consciously decided not to sell portafilter machines in Germany (as of December 2022).

We have received many messages asking if the machine can be calibrated by us. Unfortunately, we cannot offer this.