Ascaso Steel Duo PID Test: Update & Plus Version

The Ascaso Steel Duo PID pleasantly surprised us in 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 quickly heated as thermoblock machines typically are. It's also temperature stable and how stable it is really 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 Ascaso Steel Duo PID in the old version with the steam thermoblock didn't deliver as much power into the pitcher. That's exactly what the manufacturer from Barcelona has been working on. For this reason, we've devoted another video to the Ascaso Steel Duo PID New.

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

Ascaso Steel Duo PID: Strengths and Weaknesses at a Glance

After our initial measurement from our original test, our tester Michel Aeschbacher (Swiss vice-barista champion) wrote just one word in the internal team chat: "Crazy." Felix Hohlmann's response: "That's already pretty awesome." That hits it pretty well, even though we have some detailed issues with 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 frothing power (noticeably improved with the update, but still not at boiler level)
• Cup warmer overheats
• Design of the cup resting surface (cups slide 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 classical boiler espresso machine (single boiler, dual boiler, or heat exchanger):

• The temperature is at least as consistent as the better dual boiler espresso machines we've tested.
• The machine reaches full operating temperature in about 3 minutes, while heat exchangers need 20 minutes or more.
• Energy consumption is significantly lower (figures below), even when leaving the machine on continuously.
• No water sits in the thermoblock for long periods, so fresh water is heated for each espresso.
• Scaling tendency is lower than with a boiler.

In favor of a boiler is mainly stronger and more continuous milk frothing behavior, as well as the robust construction proven in commercial settings.

How the Thermoblock Duo Works

The name Ascaso Steel Duo PID comes from the two thermoblocks installed. 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 runs through a spirally coiled 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 otherwise cools the brewing temperature during extraction. We measured portafilter temperatures of 89 to 92 degrees even at rest on the Ascaso.

Energy Consumption Comparison

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

For comparison, also measured after two hours: the most economical heat exchangers in our test, the Xenia Espresso and the Bezzera BZ10, came to 0.48 kWh, while the Bezzera Magica S was the lowest at 0.72 kWh. Since the Ascaso can be switched off in between thanks to its short heat-up time, its consumption in practice could be reduced even further.

Buy Ascaso Steel Duo PID

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

• Germany: [Partner links] Stoll Espresso, Bohnendealer, Lücke Technik
• Austria: [Partner links] Bohnendealer, DieRöster

We search for specialist partners for you, knowing they provide quality work and good service. We're 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 testing equipment. We continue to work on this and are looking 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 was fundamentally overhauled. The manufacturer claims +25% power. And indeed, the machine has significantly more power when steaming. Steam pressure can now also be manually adjusted on the machine. The machine froths powerfully in about 30 seconds and heats a 0.6-liter pitcher to temperature. It can effectively circulate all the milk during the rolling phase.

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

With the new setup, we recommend purging the steam wand well first. Pressure and condensation water quickly accumulate in the wand and the line, and these would otherwise cause too much pressure to be blown into the milk pitcher when steam first starts, resulting in many large bubbles that are difficult to correct.

The Ascaso Steel Duo PID heats the milk quite gently. It takes about 30-35 seconds for the foam to reach temperature. During this time, even beginners can work through the pouring and rolling phase without stress for latte art.

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

Room for Improvement of the Ascaso Steel Duo PID

Manufacturer Ascaso took the criticism from us and many home baristas seriously with the Duo PID update. This speaks well for Ascaso and 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 things, the espresso machine will rank even higher in our personal rankings:

• The cup warmer still overheats and gets way too hot. I'd like to be able to simply turn it on and off.
• Due to the machine's angle, cups slide backward during extraction and rattle against each other.
• The included accessories are a relic of the past. The supplied double basket holds just under 15 grams and the hole openings stop well short of 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 tall, has a 2-liter water tank, and weighs 15 kg.

The build quality is particularly impressive with the portafilter with wooden handle, which is standard here but often an upgrade option on other machines. The housing itself, however, feels rather tinny, especially when tapping the side walls or cup platform. Compared to a stainless steel heat exchanger in a similar price class (ECM, Rocket, etc.), the Ascaso falls short. Inside, the wiring looks a bit haphazard, and we've received occasional reports of loosely fastened parts. The drip tray is essentially plastic with a metal bezel.

• The included tamper is suitable as a paperweight. Using it is frustrating since the sides look the same but are different sizes. The ergonomics aren't really hand-friendly either.
• The biggest problem, however, is the volumetrics. The Ascaso Steel Duo PID can dispense a desired amount of brewing water. This is initially a major pro argument for the machine compared to nearly all heat exchangers and other espresso machines that must be manually started and stopped. So it's important to note that we're criticizing something other machines don't even include as a function. In the Ascaso Steel Duo PID, the expansion valve is now positioned behind the flowmeter. This means that when bypassing a certain pressure range, some water doesn't reach the coffee bed but is diverted. So if your espresso changes with finer grinding and uneven preparation, the water amount may also reduce. Your brew time will tend to stay the same. It's therefore wise to check the cup or regularly use a scale to verify that the dispensed amount matches your desired brew ratio.

Notes on Espresso Extraction and Temperature

If your local specialist retailer has correctly set up the Ascaso Steel Duo PID, it reaches operating temperature after five minutes. That's a real strength of the machine. While many espresso machines require planning your day around their 25 to 30-minute heat-up time, the Ascaso can also be brought to temperature relatively spontaneously.

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

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

The machine's offset must be set by your local specialist retailer. You should pay attention to this when purchasing the machine. It requires a professional Scace temperature measurement device. This measurement cannot be done with a simple thermometer at home.

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

Temperature Rise During Idle Time

A newer finding for us is that the Ascaso Steel Duo PID overheats beyond the target temperature when idle for +15 minutes. However, it can be brought back to the target temperature by purging.

We set the brewing temperature so it's slightly below the target temperature on the first shot and then arrives exactly in range on the second shot. By the third shot, the portafilter is so thoroughly heated that the temperature is exactly 93 degrees.

These settings can be adjusted based on your needs. As a guide, you should consider when your preferred brewing point is. With the temperature set here, we've chosen a good compromise. The first shot is still slightly below target, but all subsequent shots, even if the machine has been on longer, are exactly in the target range (don't forget to purge first if idle longer).

These two charts show the overall very stable temperature consistency when using the KM protocol with 1-minute intervals 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, the importer of the Ascaso Steel Duo PID, offers an upgrade 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 our Ascaso with an 18 gram IMS Competition basket, for example (DE, CH).

The portafilter accommodates 58mm baskets. A tamper of the appropriate size ranges from 58 to 58.4 mm.

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