In terms of their claim of being very temperature stable, I would take that with a grain of salt.

Geek alert: I'm about to go down a rabbit hole in terms of talking about temperature stability. The waters will get muddier before they get clearer.

In the sense of a traditional HX machine, which can overheat the water in the HX if let to idle for to long, then yes, the current thermosiphon set up is an improvement in temperature stability. No cooling flush needed.

But there's a second issue when using a detached group (like the e61) in terms of overheating. Since the boiler is on the inside of the machine and the group is detached on the outside (exposed to the cooler ambient air temp), there's always a temperature differential between the two. So different methods are employed to help keep the group's temperature up. In the case of the e61 (and some lever groups) they use a thermosiphon to circulate hot water through the group. They also tend to increase the physical mass of the group to give it more thermal inertia to withstand temperature swings. With the "Bosco" lever group (same used on the Londinium) it's a whopping 7kg of brass. But regardless, detached groups run cooler than the desired final shot temp. So the water entering the group (for the shot) ends up being slightly hotter than the desired temp, the large thermal mass of the group acts like an iron to even things out, and you get a nice average at hopefully your desired temp.

Overall detached groups have been refined over time, and the system works well if you rest the group between shots (1:30-2min or so). During that rest time they dissipate the excess heat gained from the water into the environment. If used more frequently shot temps can rise, as you reach the groups thermal capacity to dissipate the excess heat. Which isn't really an issue in a home environment, but becomes one within a cafe with back-to-back shots. Or unless you live in a extreme hot location, as the ambient temperature effect's a detached groups ability to dissipate heat, and thus the final water temp (they tend to be tuned to work best in a comfortable environment for people, 20-22C or 68-72F).

It's the primary issue with a detached group, which drove the development of integrated brew group, and their eventual adoption, especially on high end machines, and multi-group machines for cafe's with lots of volume. You get stability and consistency, regardless of how much use the group gets (whether you're hammering it, or it's left idle for hours), and they also don't care about ambient temperature differences, it doesn't matter if you're in Antarctica or Dubai.

Now, that's not to say that e61's are bad, they're still a very good group. They're a refined design and work well if you give the group some time to rest between shots, and tweak it for location and summer/winter temp swings. But when it comes to the term "temperature stable" it depends on your standards and how picky you want to be. There is a reason the integrated group displaced it.

Hopefully that helps explain. It's yet another reason to get the EricS thermometer if you really care to know the exact temp. It can help you achieve consistency with your desired temp, and when comparing seasonally or with temps with others. IIrc Eric came up thermometer mod during the hay-day of temperature stability being the latest "holy grail" in espresso. David Schomer and John Bischt had just put the first PID on an espresso machine. Synesso "broke the sound barrier" with ability to maintain 1 degree fahrenheit stability during a shot. Temperature stability was all the rave. Then we discovered the natural declining temps in the lever and some hx groups tended to provide bit of a buffer/safety against over extraction. Similar benefits with the declining pressure with a lever group. They can do nice things to the coffee.

In the end, the temperature stability achieved with the integrated groups provided consistency and repeatability (which was especially appreciated within cafe's) but it didn't necessary raise the bar and make the absolute quality of the espresso better for anyone.

/End rabbit hole.

What I think their claim of "temperature stable" is trying to say is, "it's good enough for you not to worry about it". Which it probably is. To be honest, the EricS thermometer will help you solidify your understanding of what's going on with temps and the machine, help you achieve a little better consistency, and compare your info with others, all of which can be a good thing. But it won't radically help you make better coffee. Like most things, if you practice, know the quirks of your equipment and let your taste guide you, then you'll probably do just fine.

wai2cool4u wrote:i believe he could be referring to this: https://www.chriscoffee.com/E61-Group-D ... sss-04.htm

you can also purchase it from user "erics" on this forum. i believe it's slightly cheaper if you purchase it from him.

I'm in Canada so the shipping goes up much if I buy from US supplier (and sometimes Customs holds stuff up and if a broker gets involved its another 3rd party fee). From the only supplier I've seen in Canada (iDrinkCoffee.com), it is $180+tax; which makes the cost of my HX machine about $200 more. I don't feel I'd need the thermometer with the DB Pro300; as from WLL videos, their Scace seemed to measure within a degree of their brew temp PID setting.

I tried the "styrofoam cup under the brew head - insert probe" method last night on a low end system. Wasn't pretty (and only slightly indicative of my brew temp)

nickw wrote: What I think their claim of "temperature stable" is trying to say is, "it's good enough for you not to worry about it". Which it probably is. To be honest, the EricS thermometer will help you solidify your understanding of what's going on with temps and the machine, help you achieve a little better consistency, and compare your info with others, all of which can be a good thing. But it won't radically help you make better coffee. Like most things, if you practice, know the quirks of your equipment and let your taste guide you, then you'll probably do just fine.

Yeah.. if I opt for the HX, I think I'll still need an attached thermometer to get a sense of the characteristics of how the system temperature is profiling as the extraction is happening.

Thanks for the great info..

Dave

For those of you looking at the Profitec PRO 500, I had commented on Marc's (WLL) video on the Pro 500 PID questioning what would happen to the steam power if the PID were set to its lowest setting (244 degrees assuming 195 deg extraction.)

http://www.youtube.com/watch?v=eFButNxsP-Q

To my surprise he made a video showing the machines steam power as low as 0.5 bar.. I didn't think steam would be produced at that low a setting. And I'm wondering if the gauge might be a little off as the pressure gets that low. But the steam seem pretty impressive.

So comparing it to the Pro 300, I'm guessing the Pro 500 PID would still have significantly more steam power throughout the total range one would want to extract. (195 to 205).

The downside is that one would still have to monitor the basket temp for a bit to see the characteristics of your ambient environment, elevation, etc. Even with EricS thermometer, there is some 'process' needed to compute what the puck temp really is.. I've been experimenting with the 'foam cup' method below the group which actually seems to work pretty well on my low end setup. That might be enough to let me develop a workflow for consistent extraction.

Dave

Could you ask him to steam water for a cappuccino and measure the before/after weight, so see how much water is introduced?

If you would like I can do this tomorrow and let you know. Typically I steam about 6z or 180g of milk, so it would be easy to do a before/after measure for you to compare against.

I measured the steam/water gain on 175g (about 6oz) of milk. It gained 22.7g.
Doing so jogged my memory, and it usually gains about 20g.

I think the Slayer (with it's db running 1.7bar) was round 12g.

nickw wrote:Could you ask him to steam water for a cappuccino and measure the before/after weight, so see how much water is introduced?

If you would like I can do this tomorrow and let you know. Typically I steam about 6z or 180g of milk, so it would be easy to do a before/after measure for you to compare against.

It was nice of Marc to do the steam test, but I won't push my requests for another test. The steam did not sputter and did not look very wet. It sure didn't look wetter than steam I've seen come from other machines below $2k. And that was the very worst case possible. Likely the PID would be higher for 195 extraction. If you look at the HX PID review they did recently between 3 machines (Profitec, Rocket & Bezzera, I think) one of the non-Profitec machines had its PID in the mid 240's. So steam must be suitable or they'd never sell these brands. Looks like the gauge might be a little misleading.

nickw wrote:I measured the steam/water gain on 175g (about 6oz) of milk. It gained 22.7g.
Doing so jogged my memory, and it usually gains about 20g.

I think the Slayer (with it's db running 1.7bar) was round 12g.

I just tried this on my Pro 700. 175g milk gained 18g after steaming up to 140F. Not sure what this tells me though?

Pro 500 non-PID at around 1.2 bar max pressure did 190g of milk and added around 23g of water FWIW.

I wonder what the LMLM does?

wai2cool4u wrote:i believe he could be referring to this: https://www.chriscoffee.com/E61-Group-D ... sss-04.htm

you can also purchase it from user "erics" on this forum. i believe it's slightly cheaper if you purchase it from him.

THx