scaso Steel Duo PID Test: Update & Plus Version

The Ascaso Steel Duo PID pleasantly surprised us during our initial test. The machine from the Spanish company is a dual thermoblock. It embodies everything that makes a modern and good thermoblock espresso machine. It's not only as quick to heat as thermoblock machines are known to be. It is also temperature stable and how stable it is particularly surprised us in our test in early 2021. Thanks to the rapid heat-up time, the machine is also very energy efficient and consumes up to three times less electricity than dual boiler or two-group boiler espresso machines.

However, we had one point of criticism with the old model: the steaming performance of the machine left something to be desired. The old version of the Ascaso Steel Duo PID with the steam thermoblock didn't deliver enough power to the pitcher. This is exactly what the manufacturer from Barcelona has been working on. For this reason, we've dedicated another video to the Ascaso Steel Duo PID New.

In the meantime, there is a Plus version of the Ascaso Steel Duo PID. You'll find out more about this further down in the article. (Update: 30.9.2023)

Ascaso Steel Duo PID: Strengths and Weaknesses at a Glance

After the first measurement of our original test, our tester Michel Aeschbacher (Swiss Vice Barista Champion) wrote only one word in the internal team chat: "Crazy." Felix Hohlmann's response: "That's pretty damn good." That sums it up well, even though we have quite a few details to criticize about the machine.

Strengths:

• Temperature consistency from shot to shot and across multiple extractions
• Short heat-up time of around 5 minutes
• Low energy consumption compared to boiler machines
• High-quality portafilter with wooden handle included
• Control via display and volumetrics
• Side-mounted water tank

Weaknesses:

• Build quality, especially inside the machine
• Milk steaming power (noticeably improved with the update, but still not at boiler level)
• Cup warmer overheats
• Design of the cup warming surface (cups slip and rattle during extraction)
• Accessories in the base version (tamper, baskets)

Boiler or Thermoblock?

The Ascaso Steel Duo PID demonstrates well what a thermoblock can offer over a traditional boiler espresso machine (single boiler, two-group, or dual boiler):

• The temperature is at least as consistent as the better two-group espresso machines we've tested.
• The machine reaches full operating temperature in around 3 minutes, while two-group machines need 20 minutes or more.
• Energy consumption is significantly lower (figures below), even if you leave the machine running.
• No water sits in the thermoblock for extended periods, so fresh water is heated for each espresso.
• The tendency to scale is lower than with a boiler.

A boiler, on the other hand, is primarily advantageous for more powerful and continuous milk steaming behavior and the robust construction proven in the gastronomy industry.

How the Thermoblock Duo Works

The name Ascaso Steel Duo PID comes from the two built-in thermoblocks. One heats the brewing water, and its temperature can be adjusted via PID control on the front display. The second is responsible for milk heating. In both cases, water flows through a spiral-wound stainless steel tube in an aluminum block. The brewing water thermoblock sits directly above the portafilter and heats it well, a point where many other thermoblock machines fail: a too-cold portafilter would otherwise cool the brew temperature during extraction. We measured portafilter temperatures of 89 to 92 degrees on the Ascaso even at rest.

Energy Consumption Comparison

We measured power consumption with a MyStrom adapter: after 5 minutes of heat-up time and five double espresso shots, it was at 0.09 kWh. If we left the machine on for another two hours and then pulled another double, total consumption rose to 0.28 kWh.

For comparison, also measured after two hours: the most economical two-group machines in our test, the Xenia Espresso and the Bezzera BZ10, reached 0.48 kWh, with the Bezzera Magica S being the highest at 0.72 kWh. Since the Ascaso can also be switched off intermittently thanks to its short heat-up time, its consumption could be reduced even further in practice.

Buy Ascaso Steel Duo PID

The following specialist retailers sell the Ascaso Steel Duo PID and we can recommend purchasing a machine from these businesses. They all offer the option to adjust the machine's offset.

• Germany: [Partner links] Stoll Espresso, Bohnendealer, Craft Coffee Gear, Lücke Technik
• Switzerland: [Partner links] deon
• Austria: [Partner links] Bohnendealer, DieRöster

We search for specialist partners who we know provide good work and excellent service. We are in close contact with the retailers. These are affiliate links. If you order through this link, it doesn't cost you more, but we receive a small commission that we invest in new test equipment. We continue to search for competent partners for you in the DACH region.

The Steaming Performance of the New Ascaso Steel Duo PID

The steaming performance of the Ascaso Steel Duo PID has been fundamentally revised. The manufacturer mentions +25% power. And indeed, the machine has significantly more power when steaming. The steam pressure can now also be manually adjusted on the machine. The machine steams vigorously to temperature in approximately 30 seconds with a 0.6-liter pitcher. It can effectively circulate all the milk during the rolling phase.

A positive change is that milk foam is no longer started directly via the toggle switch on the machine as with the old model. Instead, the switch only starts the steam thermoblock. Steaming is now activated by turning the side wooden wheel. This eliminates another point we criticized. Steam starts immediately by turning the wooden wheel and doesn't build up first, as was the case when the thermoblock was started via the toggle switch.

With the new setup, we recommend initially blowing out the steam wand well. Pressure and condensation quickly build up in the wand and line, and this causes too much pressure to be blown into the milk pitcher on first steam activation. If not heeded, this results in many large bubbles that are difficult to break up.

The Ascaso Steel Duo PID still heats the milk leisurely. It takes about 30 - 35 seconds for the foam to reach temperature. In this time, even beginner latte art enthusiasts can comfortably work through the pour and rolling phases without stress.

On the left the new, on the right the old Ascaso Steel Duo PID. The color isn't new. White is still available. What's new is the wooden steam wheel.

Potential for Improvement of the Ascaso Steel Duo PID

The manufacturer Ascaso has taken the criticism from us and many home baristas seriously with the Duo PID update. This not only speaks well of Ascaso, but gives hope that the machine will continue to be developed further.

Today, the Ascaso Steel Duo PID is one of the five most interesting espresso machines for home use. If Ascaso addresses the following points, the espresso machine will continue to rise in our personal ranking:

• The cup warmer still overheats and gets far too hot. I'd like to be able to simply switch it on and off.
• Due to the slope of the machine, cups slip backward during extraction and vibrate against each other with a rattling sound.
• The accessories are a remnant of the past. The double basket included holds just under 15 grams and the perforations stop well before the rim. However, this can be easily improved with a basket upgrade.

Build Quality and Dimensions

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.

The build quality is particularly impressive with the portafilter with wooden handle, which is often an upgrade option on other machines but is standard here. The housing itself, however, has rather a tin-like appearance when tapped, say on the side panels or cup support. Compared to a stainless steel two-group in a similar price range (ECM, Rocket and similar), the Ascaso falls short here. Inside too, the cable routing appears untidy, and we've also received occasional reports of loosely screwed parts. The drip tray is essentially plastic with a metal trim.

• The included tamper works well as a paperweight. Using it is frustrating since the sides look the same but are different sizes. Ergonomics aren't particularly user-friendly either.
• The biggest issue is the volumetrics. The Ascaso Steel Duo PID can dispense a desired amount of coffee water. At first, this is a major selling point for the machine compared to almost all two-group and other espresso machines that must be manually started and stopped. So it's important to note that we're criticizing something that other machines don't even have as a function. With the Ascaso Steel Duo PID, however, the expansion valve sits behind the flowmeter. When a certain pressure range is exceeded, some water is diverted rather than directed onto the coffee puck. If your espresso changes with finer grinding and uneven preparation, the water amount may also be reduced. Your brew time, however, will tend to remain the same. So it makes sense to take a look in the cup, or to regularly use a scale to check if the fill amount matches your desired brew ratio.

Notes on Espresso Extraction and Temperature

If your local specialist dealer has correctly calibrated the Ascaso Steel Duo PID, it reaches operating temperature in five minutes. This is a real strength of the machine. While many espresso machines require planning your day around the machine so it reaches temperature in 25 to 30 minutes, the Ascaso can reach operating temperature quite spontaneously.

This makes the Ascaso Steel Duo PID well-suited to brewing very good espresso in a short time (see also recommendations for baskets and tamper).

However, all the espresso machines we tested were delivered with incorrect offset calibration. The brew temperature deviated between 2 and 4 degrees from the displayed brew temperature. We measured 3 machines with calibrated thermometers for this purpose.

The machine's offset can and must be adjusted by your local specialist dealer. You should pay attention to this when purchasing the machine. It requires professional Scace temperature measurement equipment. This measurement cannot be performed at home with a simple thermometer.

In this short video, we explain how offset and steam adjustments can be made.

Temperature Rise During Standby

A newer finding for us is that the Ascaso Steel Duo PID overheats above the target temperature during extended idle periods of +15 minutes. However, it can be brought back to the target temperature by flushing.

We've adjusted the brew temperature so that it's slightly below the target on the first shot and then reaches exactly the target range on the second shot. By the third shot, the portafilter is so well heated through that the temperature is perfectly 93 degrees.

These settings can be adjusted according to your needs. As a guideline, you should consider what your preferred brewing time is. With the temperature we've set here, we've chosen a good compromise. The first shot is indeed slightly below target, but all subsequent shots, even if the machine is left on for longer, are exactly in the target range (don't forget to flush before longer idle periods).

These two graphs show the overall very stable temperature consistency when using the KM protocol with a 1-minute interval between shots. We measured a standard deviation of 0.75 here, which is a very good value.

Upgrades for the Ascaso Steel Duo PID

In Germany, Espressopool as the importer of the Ascaso Steel Duo PID offers an update service for the old Ascaso model. This can also be performed by local specialist retailers.

We recommend different baskets and a matching tamper for the machine. Your local specialist retailer can advise you. We upgrade the Ascaso with an 18 gram IMS Competition basket (DE, CH).

The portafilter accepts 58 mm baskets. A corresponding tamper ranges from 58 to 58.4 mm.

Want to try the machine before buying? It's available for testing at our academies in Basel and Dinslaken upon request.