A glimpse into 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 heating time, yet has relatively low power consumption for an espresso machine. The combination of these features left a lasting impression on our testers Michel Aeschbacher (Vice Barista Champion in Switzerland) and Benjamin Hohlmann (German Cup Tasting Champion).

The Ascaso Steel Duo PID was tested as part of our thermoblock test series. After an extensive test series with heat exchanger espresso machines, we are publishing another espresso machine test week by week.

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

First impression of the Ascaso Steel Duo PID

The Kaffeemacher espresso machine aficionados are in a shared WhatsApp group. There, we share machine impressions, draw attention to outstanding espressos or interesting content. Test results are also summarized there in short, concise words. Michel's comment after the first measurement of the Ascaso Steel Duo PID was simply "awesome". The following screenshot of the first measurement of the temperature curve of the Ascaso Steel Duo PID was attached. Felix's answer: "that's pretty cool".

That really sums up a lot of what we will elaborate on below. To anticipate: there are also some things we would like to see improved on the Ascaso Steel Duo PID. Nevertheless, in many respects it is also an indicator of the directions future espresso machines can take. Namely, towards thermoblocks or smaller boilers, towards energy saving and fast heating. These are all really strong arguments for an espresso machine for home use.

Strengths and weaknesses summarized

Strengths

• Temperature consistency from shot to shot and over multiple extractions
• Heating speed (3 minutes)
• Energy consumption
• Espresso quality (can be increased with simple upgrades)
• High-quality portafilter with wooden handle
• Control (volumetrics, display)
• Side water tank

Weaknesses

• Workmanship, especially internally
• Milk foam power
• Machine heating
• Design of the cup standing surface
• 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 with a PID control via a display on the front of the espresso machine. A second thermoblock is responsible for preparing the milk. In both cases, water is passed through a spirally rolled stainless steel tube, which lies in an aluminum block. The thermoblock responsible for the brewing water sits directly above the portafilter and ensures good warming of the portafilter. Ascaso does this significantly better than other thermoblocks we have tested so far. These constantly struggle with the portafilter temperature being too cold. This automatically leads to a cooling of the brewing temperature during brewing, 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 idle.

The heating time of the thermoblock duo itself is not spectacular. As with all other thermoblocks, the machine signals readiness very quickly (after 3 minutes). The speed only becomes really exciting when the Ascaso Steel Duo PID is then truly ready for operation - in the best sense of the word.

Temperature consistency - Catalan Champions League

When it comes to brewing temperature, the Ascaso company delivers what makes a thermoblock an almost unbeatable technology for heating brewing water for espresso preparation: consistency at its finest. Both during extraction and from shot to shot, the Ascaso Steel Duo PID can compete with any heat exchanger espresso machine we have looked at. The brewing temperature glides along like a line, and the temperature change over 5 double shots in 5 minutes is only one degree. This is Champions League quality, what the company founded in Barcelona in 1962 brings to the brew group. And to stick with football examples: next to it, the 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 broke over it with a new kind of tiki-taka football between 2008 and 2012.

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

Boiler versus Thermoblock

There are few arguments remaining for a boiler espresso machine for home use when a thermoblock performs as the Ascaso Steel Duo PID's brewing thermoblock does. Boiler and kettle machines include single-circuit, double-circuit, and dual-boiler espresso machines.

• The temperature is at least as constant as the temperature of the better heat exchanger espresso machines we tested.
• The machine is at full operating temperature within approx. 3 minutes (whereas heat exchanger espresso machines take 20 minutes or more).
• The machine has significantly lower energy consumption (see next point), even if it were not switched off, which is quite possible as it heats up quickly again.
• Furthermore, water does not sit in the boiler. Fresh water is supplied for espresso preparation.
• A lower tendency to calcification is another pro argument for a thermoblock.

Arguments for a boiler:

• Better milk frothing behavior, both in terms of power and continuity of steam output.
• Proven tractor mentality in gastronomic settings.

We can't think of many more arguments for a boiler if a thermoblock performs like 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 following 5 double espresso shots. We used an adapter from MyStrom.ch for this. The measurement showed a consumption of 0.09 kWh.

After another two hours, we performed another double espresso extraction. The consumption was then 0.28 kWh.

The second value can be compared with the consumption of 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 Bezzera Magica S was at the bottom with 0.72 kWh.

It should be noted here that due to the short heating time, the Ascaso Steel Duo PID could also have been switched off. In that case, the consumption value after two hours would have been further reduced.

Machine processing

One of the biggest criticisms of the machine is its workmanship. The exterior of the machine appears tinny, especially if you knock on the side panels or the cup stand. Compared to a stainless steel behemoth in the heat exchanger class in the same price range, ECM, Rocket and co. win the race.

However, the Ascaso Steel Duo PID counters this with one of the most beautiful portafilters in the standard scope of delivery. A wooden handle is an upgrade on many other machines, but it is already included here. A look inside the machine is not for friends of neat cable routing. Perhaps the tiki-taka tactic was at play here, but rather to the detriment of the machine. Everything that is laid out seems a bit messy. We have received feedback from users of the Ascaso Steel Duo PID that screws were not properly tightened and cables were pinched. We could not confirm this, but we did find a fallen off plastic cover. Not serious, but an expression of the fact 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 initially makes a good impression. But if you look closely, you will find unpleasant side effects. The drip tray is actually made of plastic and only has a metal panel. The incline of the cup stand ensures that the cups slide backwards during extraction due to vibration. Even if you initially place the cups far apart, they cuddle together at the end of the shot at the back of the stand. The result is a cup-clinking orchestra that turns up the volume.

In our opinion, the cup warmer provides far too much temperature. We would advise disconnecting it at the internal plug. You don't need cups that warm. The machine still provides enough waste heat, at least when it's on for a longer period. If you only use the machine briefly, then the heater certainly makes sense.

Espresso Quality of the Ascaso Steel Duo PID

For many steps on the way to the perfect espresso, the barista is responsible. Coffee-to-water ratio, 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 fundamentally delivers here enables a perfect espresso. Constant brewing temperature and constant pressure are the fundamental factors for a good result.

And so we drank many good espressos (our Dreispitz Espresso, to be exact) and yet we improved the quality even further with two small interventions. Firstly, we replaced the shower screen of the Ascaso Steel Duo PID with the IMS Competitions shower screen. This makes an incredible difference in distribution. The water is thus distributed very homogeneously over the entire coffee. Secondly, we replaced the filter baskets with these IMS baskets (size 24.5). Their holes reach closer to the rim than those of the small included baskets, which hold almost 15 grams. In addition, with a filling volume of a good 19 grams, they allow for longer drinks to be extracted. 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 sieve upgrade. The machine can then also be used very well with our tamper.

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

If you primarily drink milk-based beverages, the Ascaso Steel Duo PID is probably not perfectly equipped for you. This is because its milk frothing 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 milk with the Ascaso Steel Duo PID using a 600ml milk jug, but it requires a lot of practice and experience to simultaneously stretch and roll the milk (see also our Latte Art Tutorial on our Youtube channel).

We recommend using the small 350ml milk jug. With some practice, you will succeed in making milk foam. However, if cappuccino and co. play a major role in your beverage selection, we would rather recommend 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. Above all, its temperature consistency stands out. This demonstrates what is possible with thermoblocks. With such consistency, even over multiple extractions, the machine is an indicator of possible developments in the field of espresso machines for home use.

Many classic espresso machine manufacturers continue to rely on large boilers that need to be heated and maintained at temperature. In theory, these are then consistent, although our heat exchanger test also showed that this does not apply to all machines. However, one thing is certain: 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 adjusted with thermoblocks, then we are curious to see how this will inspire the market. We look forward to what may happen in this area in the coming 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 we can calibrate the machine. Unfortunately, we cannot offer this service.