Yes very true, although it will be my more practical setup for awhile and I will be swapping out the cottage setup more frequently. I want something smaller and straight forward. Double boiler will replace my current cottage machine if anything first. With that being said there's lots to be considered in this price range and I'm interested to explore all options.

Jeff wrote:A PID on virtually any HX machine is little more than a marketing bullet point. The steam-boiler temperature is so unpredictably far, thermodynamically, from the group and brew temperature, that you still need a flush routine.

I've read this so much that I believed it as well. Altough this might be true for most E61 HX machines, the Rocket Evo R doesn't need a cooling/stabilising flush. Neither does the Mara-X.

For what has become a mantra for many (PID's are useless on HX), I'm not sure it holds up any longer. My Evo R with temperature sensor is so stable before, during and after the shot, that I only use it rarely to see if the machine's fully warmed up (even that became obsolete with a timed smart plug). This wouldn't be possible without the PID, that also allows you to play with different temperature settings (not so useful, but can sometimes help finetune).

I wouldn't want any machine without PID.

Thehomebrewcoffee wrote:Why did you get rid of your classika? Again I'm not doing more h than 1 milk drink per session if that. I'm very keen on this machine and it still holds #1 spot for me. Thanks

The only reason really was that I wanted to try something different. I was really fascinated with levers and eventually landed on a Cremina.

Thermosiphon restrictors can get you a walk-up first shot without a flush, but the problems with them and the second shot are well documented in other threads here.

Many of the early, commercial E61 machines had a tunable restrictor. This was to match the rhythm of the barista with that of the machine. Should the group rebound close enough in a minute, 90 seconds, two minutes, ... , so that the next shot during your "in the groove" times will be at roughly the right temperature. You can't ignore that pulling a shot adds cool or cold water to the system and drops its temperatures significantly. You will have a sawtooth as a result.

I did also note (The Lelit MaraX is a notable exception, as it monitors the group/HX temperature and swings the steam boiler to do a good job of keeping it within reasonable bounds.) This is not the same as controlling the steam-boiler temperature as the output. I consider it a clever design and implementation and one of the things that, for me, sets Lelit apart from other manufacturers.

The other approach is a fan on the E61 group and control the group temperature by varying how fast is spills heat. Not only is it an insightful way to manage the temperature, but it highlights the overall sensitivity of the E61 system to airflow and other ambient conditions.

cafeIKE's approach for effectively converting an HX into a PID-controlled single-boiler addresses the thermodynamic problems of the HX/E61 system for home use by effectively eliminating the HX part of it. Run the "steam" boiler at a temperature comparable to that of a dual-boiler brew boiler and you're close in shot-start stability to an E61 dual-boiler. (There are probably some secondary effects due to the relatively small HX capacity during the shot, but there isn't any strong evidence that a declining-temperature profile during a shot is a bad thing, and some that suggest that it may be a good thing.)

Those that pull classic roasts for a living, or roast for those that do, probably consider all of this concern around temperature as hogwash. The best Italian roasters come up with a blend and roast that works in just about anything, at just about any pressure or temperature.

However, if you want to get consistently good to great results from what I call medium and lighter roasts, control and repeatability move out of the background.

@Jeff, so to summarize you're talking about pulling shot to shot and temperature stability inbetween? That's where most prosumer machines don't shine, right? Neither HX or SB machines, and not even most DB's excel at this either since they use the same E61 grouphead.

From my experience, 1-2 shots + milk works fine on a Rocket PID HX (I never did more than 3 in a row on this machine yet). Temperature is right back on after the first shot is complete. Here's a video of my Rocket where temperature hovers around 92-95 degrees during the shot (this walk-up shot was with no pulls in the hour or so before). For a 2nd I do flush between shots to clean the screen, but temperature-wise this isn't necessary.
A DB can probably do more shots in a row slightly more consistent, but I doubt a HX machine without PID can do this.

Ypuh wrote:@Jeff, so to summarize you're talking about pulling shot to shot and temperature stability inbetween? That's where most prosumer machines don't shine, right? Neither HX or SB machines, and not even most DB's excel at this either since they use the same E61 grouphead.
A DB can probably do more shots in a row slightly more consistent, but I doubt a HX machine without PID can do this.

There is nothing in the Evo to form a close loop control system. So any influences on the E61 will influence the final brew water temp.. (Air conditioning fan, seasonal room temp differences, etc). You are right for 1 shot, you won't notice much of a difference between this and a DB if your PID temp is matched to your workflow to give you the brew water temp you want... and the stability comes from the big brass mass of the E61, not the PID. The fact you don't need a cooling flush is due to the restrictor in the thermosiphon, not the PID. Remove the restrictor and you'd be flushing all day.

If you were doing 5-6 shots for friends, you may find quite a bit of difference between your final brew water temps and your first.. Successive shots are where the restrictor in new HX designs can cause issues. For instance in my Pro500 PID, it takes 20 minutes to rebound between shots #2 and #3. Rockets have a larger restrictor and generally are faster to rebound. But generally the longer you leave them on, the hotter the group, (the PID is irrelevant here), and so a cooling flush is required. If you get a chance to borrow a SCACE, it if fun to note the relationship to your group thermometer reading and the actual brew water temp (they will be slightly different and will vary based on your workflow) if you pull, say 5 shots, and do them 2-3 minutes apart.

Non-PID HX machines with larger restrictors require flushing initially, but when you get your workflow going so you have, say 2 minutes between shots, can provide endless offerings. I cannot pull more than 3 shots without a large time wait. Which is really bad performance if you want to entertain a small group of people (at the price of these HX machines).

Really if you were only considering a single shot at a time, a Robot, Flair58 or such makes much, much more sense.. other than you can't steam milk.. Hence the large interest in seeing how the Odyssey turns out.

For instance in my Pro500 PID, it takes 20 minutes to rebound between shots #2 and #3.

This can be caused by poor water injection management and / or sensor location and / or restrictors and / or PID tuning and / or PID location. I got one of the earliest Vibiemme DB for my office and had to futz with the first four to achieve 'coffee break back to back to back repeatability'

Earlier this year, I decided to rebuild it. I moved the PID from next to the brew boiler and removed the heat trapping cover. Now that it's in a cool 40°C location instead of 100°C+, new PID parameters have made it even better.

It ain't purty, but as my dear old Nan was oft heard to opine, "The proof of the pudding is in the eating."

Yes, shot-to-shot, measured in the basket, with an uncertain time between shots.

Probably better to discuss on another thread

A couple of the threads on user experience with thermosiphon restrictors not meeting marketing claims

HX-PID SCACE measurements (Profitec Pro 500)

Profitec Pro 500 PID consistency, rebound issues

Some technical details at Thermosyphon tuning vs. group flushes for stable brew temperature that help explain why there's no "magic" with a PID controlling an E61 HX's steam boiler to a fixed temperature. As I recall, my HX had a deadband of something like 1.1 to 1.4 bar, about 122°C to 126°C, with a period much, much faster than what I believe the time constant of an E61 group, so that would be filtered heavily.

Interesting. To bring it back on topic; I've got the specific Rocket machine and am very happy with it. No flushing required (I do it to heat/clean the cup and screen, not for quality of the coffee). To summarize above, if you want milk, a HX is nice. If you usually do 1-shot at a time, the Evo R is near perfect in my opinion.

For enteraining (more than 3 cups at a time), look elsewhere. If you make 4-5 cups at a time 3-4 times a day, you probably would've already looked elsewhere in the first place (at least a DB, possibly even a 2 group). The Bianca is a well loved DB, but the boilers are still rather small so I doubt that solves the issue of 3-4 cups at the same time.

I did learn something new today so thanks for that Jeff and Bluenoser, but question its relevance. As OP states, he only makes coffee for himself. Sometimes also his GF. A Rocket Evo R seems just capable of handling that perfectly, and the steaming capacity and plumb in option give it a one up to the ECM Classika.