Ascaso Steel Uno Professional w/ PID: is the thermoblock an issue?

#1: Post by **Ursego** » July 27th, 2019, 7:48 pm

I am thinking to upgrade my current Breville Infuser.

Every morning, before going to work, I leave the portafilter with tamped coffee on the countertop; later, my wife inserts it into the Breville and clicks one button to get her espresso. We want to keep that ceremony, so the volumetric dose control is a very nice feature to have. Other requirements:

The standard 58 mm portafilter.
PID.
Manometer (not a must, but nice to have).
Single boiler (we NEVER prepare drinks with milk, so a dual boiler or HX would be waste of money).

The only option I see is the Ascaso Steel Uno Professional w/ PID (please let me know if I missed something). There is nothing perfect in the world - same with that espresso machine: it has a thermoblock. Currently, I am using a machine with a thermocoil, and I love the idea of heating water on demand: the machine is ready to use in less than 1 minute after switching on (even though a programmable timer can be bought for any machine, even a wi-fi smartphone-driven). But I have read that "thermoblocks are installed in cheap espresso machines; if espresso is your serious hobby, then you should buy a normal machine - with a regular boiler or HX". So, what are the problems (issues, dangers) of buying Ascaso Steel Uno Professional w/ PID from the viewpoint of thermoblock? If reliability and durability only, then I can buy an extended warranty (but it's only for a few years, so the 10-15-20 years of using, as in normal-boiler machines, are very questionable - do anybody have concrete thoughts about that?).

Probably, somebody would suggest me to think about Breville Dual Boiler which has the volumetric dose control (and the same price - even though it is dual boiler). But there is a reason why I don't consider BDB.

If the thermoblock is not acceptable, then I will think about Quick Mill (Silvano Evo or Alexia Evo) or ECM Classika PID, so I will teach my wife to put the cup on a scale, and stop extraction when the desired weight is reached - not a big deal, in fact...

#2: Post by **baldheadracing** » July 29th, 2019, 6:54 pm

The advice about thermoblocks is old. Early thermoblocks were built for inexpensive machines; it was not so much that the technology was good or bad; but some implementations had issues. For example, some early thermoblocks were completely Aluminium; this led to corrosion.

The Ascaso thermoblock is, I believe, on its second revision. It was unique at its introduction a few years ago for using stainless steel tubing to carry the water to prevent corrosion, etc. At the time, Ascaso put out a lot of information about how temperature stable the thermoblock was. I did pick up an early Ascaso thermoblock for a project, but never got around to using it.

In the past few years, Ascaso has moved its smaller machines from small boilers to (its own) thermoblock. First it was the machines with 250ml boilers like the Basic and Dream; now it is the Uno Pro, which used to have a 350ml (IIRC) boiler, similar to the Pro 300, Quick Mill Silvano, etc. Besides lower costs in comparison to a boiler, one suspects this had something to do with reliability, as people can burn out small single boilers by steaming too much.

Unfortunately, I do not know of any third-party testing of Ascaso's thermoblock machines.

One other machine to consider (volumetric, 58mm, PID, etc.) is the Bezzera. Both the BZ07 and BZ10 are available in versions with all the features you want, although these are HX machines so the PID doesn't offer the same functionality. I also don't see the need for the additional expense of an HX given you are not steaming milk.

Finally, one last thing about the Steel Uno - a few years ago these machines had a reputation for sometimes being noisy due to vibrating metal panels. You might want to ensure that is no longer the case if noise is a concern ...

August 2nd, 2019, 4:17 pm

Great news! Ascaso have thermocoil, not thermoblock! Thermocoil is a fantastic thing, I love it im my current Breville Infuser! No idea why Ascaso call it "thermoblock", but it's a typical thermocoil:

I think, it makes sense for Ascaso to google thermocoil vs thermoblock and change their terminology since many people think it's the piece of garbage, usually installed in 50 dollar "espresso machines".

#4: Post by **baldheadracing** » August 2nd, 2019, 8:49 pm

It's semantics. Ascaso is using a thermoblock. It is also a thermocoil; not because the material, but because, to grossly simplify fluid mechanics, the water goes around a curve - a coil. It is the coil shape that determines that it is a thermocoil. Thus, it is possible that a thermoblock is not a thermocoil; just as it is possible that a thermocoil is not encased in a thermoblock. The way to think of it is that Ascaso's thermoblock has a thermocoil within it. I suspect that Breville popularized "thermocoil" because of the bad reputation that thermoblock machines had/have.

August 3rd, 2019, 7:46 am

baldheadracing wrote:Ascaso is using a thermoblock. It is also a thermocoil

In the coffe community, two the terms mean different things, so we have no choice but to accept that terminology

:

A thermoblock as well as a thermocoil are each heating elements for an espresso machine. A thermocoil can be a modern day and much more effective way of heating the machine, but it really is also much more pricey to create as it is a strong piece of steel. A thermoblock is composed of two components of steel welded collectively. It is a lot more prone to breaking, but might be created at a reduce expense.

...

Thermocoils are a one-piece cylinder that flash heats water in a number of holes. 1 advantage towards the thermocoil is the fact that it is much less probably to leak. One more is much more constant water temperature. The water flows, circularly, till it is heated and by the time it exits the thermocoil it is hot enough to utilize. Because of the style from the thermocoil, the water heats a lot more evenly.

https://glo-gadget.blogspot.com/2018/07 ... whats.html

Thermocoil heating elements function similarly to thermoblocks. These elements still pull water through the heating element. The difference is that instead of pulling the water through a multiple piece chamber, they use a tube.

https://www.seattlecoffeegear.com/blog/ ... ermocoils/

Two the pieces of a thermoblock:

Tha fact is that Ascaso Steel Uno Professional w/ PID has a thermocoil (very good thing), but the company says in ads and specs that the machine has a thermoblock (very bad thing). I think it leads to big financial losses.

#6: Post by **Lcapp** » August 6th, 2019, 10:53 am

I would think the temp.stability in a thermoblock/thermocoil would be a issue compared to a relatively large boiler like that on a ECM Classika. Thermoblocks have only about so much water heated to right temp. before the pumps push in cool water from the tank. So, in theory I guess, without having a Scace measuring device, your initial first few ml.of coffee would be at correct temp.but last few ml.of coffee would be brewed at below ideal temp.

August 8th, 2019, 9:16 pm

From what I read the thermocoils heat the water "on the fly" so it should in theory stay the same temperature no matter what the temperature of the source is

Randy

#8: Post by **Carneiro** » November 21st, 2019, 8:28 am

There is some inertia as the aluminium block is very quick to heat up but keeps not so much heat per volume as brass, copper and steel (specific heat is double but density is one third - copper would be great but very expensive).

I imagine some code tune up could compensate this. PID algorithms are made for the stability and great for the boile/thermoblock temperature at the shot start but a proportional power to the water flow during the shot could be more efficient considering a powerful heat element.

Anyways, does anydoby have any measurements of Ascaso PID thermoblock group? So much lever fans say about the declining pressure and temperature, I consider some temp profile could be nice and give the machine its character.

November 21st, 2019, 6:44 pm

slipchuck wrote:From what I read the thermocoils heat the water "on the fly" so it should in theory stay the same temperature no matter what the temperature of the source is

The temperature of the thermoblock/thermocoil itself stays the same. But not necessarily the water which has passed through it. Guessing why? Thermocoils have a huge problem which, probably, is the reason why they are not used widely even though their idea is looking super-cool (cheap in production, have very short warm-up time and close to zero recovery time, and you don't keep same water hot in the boiler for weeks). They look ideal, but they are installed literally in a few models among hundreds on market. Have you already guessed what the issue is? OK, here is the answer:

In machines with thermoblock, thermocoil and heat-exchanger, brew temperature is flowrate dependent. A slow flowing shot (finer grinding and/or low brew ratio) will be hotter, a faster flowing shot (coarser grinding and/or high brew ratio) will be cooler.

Copypaste from the Internet:

small flowrate differences will have a rather dramatic effect in temperature. For instance, a shot that flows 10% faster will have a brew temperature that is about 7°c lower. Same goes for faster flowing shots

When you have dialed in, you will have drinks of a same temperature since the water will move through the thermocoil with the same speed, so the heat will being applied during the same time. But, while you are dialing in, and before you have found the correct grind size, water will enter the group having different temperatures. Don't forget, that temperature is one of the factors which affect extraction (and, hence, the grind size)! So, water flow speed affects temperature in the group > temperature in the group affects grind size > grind size affects water flow speed - it's like a snake which bites its own tail (or recursive call, as we, programmers, say). You get unpredictability on top of all the variables espresso hobbyists struggle with. But even after successful dialing in, you don't have full control on the value of temperature. Let's say, you programmed the PID for 93 C. But with which flowrate was it tested by the engineers? An average one? And what about different brew ratios? When it's 1:3, the water is flowing fast and, maybe, doesn't have enough time to get properly hot, while in 1:1.5 brew ratio water is flowing slowly - will it be hot like hell while you see the same number on the display?! In the regular classical boiler, the water will come to the group head with the same temperature regardless the flowrate.

I didn't know all that when I was buying the Ascaso (I found that info later) and bought it because it had volumetric dosing. Which... didn't work! Weight of each shot was too different, looking more random than pre-programmed. Soon, I paid attention, that the dosing was programmed by time (even though it's officially called "volumetric"). Unfortunately, that kind of programming doesn't work for me since my habit is to use the time as the indicator of grind size correctness while the brew ratio (i.e. the shot weight) is kept constant. For example, for the same brew ratio, the difference in the taste of a 20 sec and a 35 sec shots will definitely be felt, but it will not be super-drastic (any of these shots will be drinkable even if not ideal), so I have enough room for a mistake in grind size. But if the time pre-programmed, and I get 30 g once, and then 40 gr (absolutely different brew ratios!), the difference in taste will be huge. So, I returned the Ascaso uno w/PID to the store and bought another machine (third, after two attempts - Lelit Victoria and the Ascaso).

#10: Post by **slipchuck** » November 21st, 2019, 7:53 pm

Ursego wrote:The temperature of the thermoblock/thermocoil itself stays the same. But not necessarily the water which has passed through it. Guessing why? Thermocoils have a huge problem which, probably, is the reason why they are not used widely even though their idea is looking super-cool (cheap in production, have very short warm-up time and close to zero recovery time, and you don't keep same water hot in the boiler for weeks). They look ideal, but they are installed literally in a few models among hundreds on market. Have you already guessed what the issue is? OK, here is the answer: brew temperature is flowrate dependent. A slow flowing shot will be hotter, a faster flowing shot will be cooler. Copypase from the Internet:

When you have dialed in, you will have drinks of a same temperature since the water will move through the thermocoil with the same speed, so the heat will being applied during the same time. But, while you are dialing in, and before you have found the correct grind size, water will enter the group having different temperatures. Don't forget, that temperature is one of the factors which affect extraction (and, hence, the grind size)! So, water flow speed affects temperature in the group > temperature in the group affects grind size > grind size affects water flow speed - it's like a snake which bites its own tail (or recursive call, as we, programmers, say). You get unpredictability on top of all the variables espresso hobbyists struggle with. But even after successful dialing in, you don't have full control on the value of temperature. Let's say, you programmed the PID for 93 C. But with which flowrate was it tested by the engineers? An average one? And what about different brew ratios? When it's 1:3, the water is flowing fast and, maybe, doesn't have enough time to get properly hot, while in 1:1.5 brew ratio water is flowing slowly - will it be hot like hell while you see the same number on the display?! In the regular classical boiler, the water will come to the group head with the same temperature regardless the flowrate.

I didn't know all that when I was buying the Ascaso (I found that info later) and bought it because it had volumetric dosing. Which... didn't work! Weight of each shot was too different, looking more random than pre-programmed. Soon, I paid attention, that the dosing was programmed by time (even though it's officially called "volumetric"). Unfortunately, that kind of programming doesn't work for me since my habit is to use the time as the indicator of grind size correctness while the brew ratio (i.e. the shot weight) is kept constant. For example, for the same brew ratio, the difference in the taste of a 20 sec and a 35 sec shots will definitely be felt, but it will not be super-drastic (any of these shots will be drinkable even if not ideal), so I have enough room for a mistake in grind size. But if the time pre-programmed, and I get 30 g once, and then 40 gr (absolutely different brew ratios!), the difference in taste will be huge. So, I returned the Ascaso uno w/PID to the store and bought another machine (third, after two attempts - Lelit Victoria and the Ascaso).

I could be getting this wrong but only the steam is produced by the thermo coil. The hot water is in a brass boiler and controlled the the pid from what I read
Please correct me if I am wrong

Randy