My short list for upgrade is down to 3, (come on April 15, get here already) but have a question about temperature surfing with the VBM Domobar Super.

I've read the various threads on temperature surfing, but I'm not sure what is different about the Domobar Super. Let's say it's adjusted for a stable 200 degF like in the review, and I'm pulling a shot with Vivace Dolce with a recommended temp of 203.5. Can I do a flush and recover, and start the shot at 199 on the EricS group thermometer?

I know it is all about the taste, and in the end on any coffee it's experimentation to fine tune, just curious if there are limitations placed on the brew temperature by the thermosyphon restrictor.

Thanks.

Thanks, that makes perfect sense. It's seems like a balanced system that's always trying to maintain equilibrium. I imagine different techniques help you explore the upper or lower end of the comfort zone, flush & recover may be better for the lower end, flush & go or blind flush may be better for the upper end?
All I can say is the wait for the new machine is killing me.

Dan is right on. You're also on the right track with EricS' thermocouple adapter (absolutely necessary accessory!).

Just to add - if you want to have a cool shot, then you need to overflush (compared to your normal shot), and then wait the right amount of time to have a constant brew temp (longer than your normal shot - if you want a flat profile). If you want a hotter shot, then you underflush and have a shorter recovery time. You might want to use a stopwatch in the beginning to get a better idea of how to manipulate the variables. After a while, you'll get a better feel for how to pull a 201' vs. 205' shot.

Different set-ups will tend to favour a particular sweet spot. My Elektra runs at 1.05 bar at the top of cycle. That tunes it into the 199-201 range depending on the flush. I can get lower and higher by varying the flush and recovery time but at that setting, it wants to run around 200. Right now I am working a coffee that takes a higher temp, 202. So I have to flush 3 seconds and wait 10 seconds before I pull my shot to get 202. If I had the boiler at 1.2 bar, a 3 second flush and 10 second wait would get me another flash boil. You just have to play with you system and learn how it responds. Eric's adapter will help you.

This is where experience comes into play. There is no magic bullet, you just have to pay attention to what you are doing and see how the coffee tastes. Then adjust accordingly. After a few months you wont need the adapter any more because you know how your machine will respond. This is where a double boiler shines. You just set the temperature you want and go, which is handy but you pay a premium for that. I can reliably get half degree or less target temperatures on my HX machine on the fly. No need to make a PID change, wait 15 then try again, just adjust the flush a little and pull another shot.

Once I upgrade I'll have to see about getting my hands on a scace thermofilter. It would be informative to run a series simulated shots to show thermal performance over time. I'd love to see for instance if you do a flush & recover to various temps (down to 180, 185, 190, etc.) do the recovery curves line up, and test limits or what you do around the sweet spot, and where the linearity of the temperature curve starts to break down. Sounds like a good experiment for a rainy afternoon. I've already seen where someone has charted the steady state grouphead temp's for a VBM at different pressure stat settings.

A quick way to judge visually & it works on my Bezz
Lock in an empty group handle
Turn on machine to flush
View the water cascade and when it runs like an ideal coffee pour turn off
It will be spot on temperature
Then load tamp & proceed with your coffee extraction as normal

KK

Koffee Kosmo wrote:A quick way to judge visually & it works on my Bezz
Lock in an empty group handle
Turn on machine to flush
View the water cascade and when it runs like an ideal coffee pour turn off
It will be spot on temperature
Then load tamp & proceed with your coffee extraction as normal

Espresso flow rate is about 1ml/sec for singles, 2ml/sec for doubles. The unimpeded flow rate is many times this (7-8ml/sec on my machine). Espresso pours as crema, and looks nothing like water at any flow rate on any machine that I've ever used. The comment about temperature is even harder to justify.

No disrespect intended, but I don't see how this can possibly be correct.

The questions was

Temperature surfing an HX espresso machine?

The method I use and posted is more to do with how to consistently judge a cooling flush that has a visual sign

I suggest you try the method & report back on your observations

KK