Hello,

I have a Rocket Appartamento HX machine coupled with an Eric's thermometer. I want to make sure I'm using it the thermometer optimally. To that end, should I be reading the thermometer with the understanding the water is cooler or hotter at the shower screen (where it makes contact with the puck)?

Thank you,

I believe it will be a little cooler at the screen.

Right, that's what I originally thought but apparently it isn't always the case.

"It depends..."

The inlet brew temperature is going to be a mix of the temperature in the HX, that in the reservoir, and the heat stored in the group head. If you use "flush-and-go" timing then the water in the HX is typically cooler than the group head (group is still cooling down from the flush), If you use "flush-and-wait" timing, the water in the HX is typically hotter than the group head (group is rebounding).

Basically, pick one timing, stick with it, and decide what your own "normal" temperature is. That will vary based not only on timing and machine, but even from machine to machine, and even more if you're getting scale accumulations.

jtferraro wrote: ... but apparently it isn't always the case.

Yes. There are different approaches to flushing that affect the difference between the group thermometer temp during a pull and the expected temp at the puck. If you start with a hot group, then do a flush right before the pull (flush-n-go), then the group temp indication at midpoint of the pull is likely somewhat cooler than what's hitting the puck. If you do a long flush well beforehand and wait to let the group come back to a point closer to your desired brew temp (flush-n-wait), then the thermometer will usually show a temp higher than what's hitting the puck.

A lot of searching on this site* will uncover discussions and graphs of Scace device measurements of the two approaches on different machines.

The common sense behind it is:
- When not pulling a shot, the thermometer indicates the temp of the group. This 'idle temp' is influenced by machine design, boiler temp, and ambient temp at the group. It can go unexpectedly low if you have a problem like a thermosyphon stall. My idle temp can vary by about 3℉ depending on room temp and ventilation (my machine is near an open kitchen window.)
- When the shot is flowing it represents the temp of the water flowing past the tip of the thermometer. This water may have been heated or cooled a little by the heavy brass group, and may be heated or cooled a little more by the time it hits the puck. Whether it's heated or cooled depends on the relative temp of the flowing water and the temp of the group.

P.S.
Jeff provided an excellent reply while I was typing this. I'll add that I practice two approaches for my HX. I normally do a flush-n-go, but revert to something like a flush-n-wait when pulling multiple shots in succession.

* here's a start: Rocket Appartamento boiler temperature and flush time and
How to systematically develop HX flushing routines per target brew temperatures?

Thank you! I was afraid this question was going to potentially open a can of worms. I need to start drinking more espresso straight, rather than frequently making milk-based drinks, to determine what truly tastes good and what doesn't. I've been doing more of this lately, but probably should be drinking it exclusively. Would you agree? I also need to do more experimenting (and reading!).

I was hoping somebody with an Appartamento (or another Rocket HX) and Eric's thermometer would share their experiences and suggestions re: what they've determined, what they recommend, and what their existing routine entails to create the best shots possible.

Thanks again,

Drink espresso as you like it. That's the point!

If you want to learn a bit more about the taste, let it cool a bit, stir, take a sip, and put the rest into the drink of your choice. That may help you pick up hints of sour, bitter, or astringency that you might miss in a milk drink.

Many people prefer one flavor profile coffee for milk drinks and a different one straight. Don't be surprised if a killer straight shot is not the best in milk or vice versa.

If someone with a similar machine doesn't provide suggestions for a starting point with the EricS thermometer, your machine vendor may be able to help. Either way, your "idle" temperature and your "pull-at" temperature are likely to be a few degrees different than others', but that should be a good start.

Thanks Jeff - good points. I re-watched Dan's 'Newbies' video, specific to HX machines (Dragon, Mixer, Agnostic) and feel, for me, it's a blessing and a curse they offer such a significant degree of manipulation. While I love manual transmission cars, I cannot yet say I love HX machines. More to come...

Take my experience with a grain of salt as I've only had my Appartamento for a little over a year. I'm a flush and go.

My idle temp typically sits at 207f. After I'm done grinding and prepping my basket I'll start my flush which will jump my temp to about 209-211 depending. I'll finish my prep and stop my flush at around 205 (I'm generally aiming for about 200f durning my shot). I'll put my portafilter in, setup my scale and cup and turn on the machine All within about 5-10 seconds. If I'm making a straight shot ill watch the temp and generally it will start around 203-204 and end around 199-200. I've been making a lot more milk based drinks to practice my art so don't usually pay super close attention to temp durning the shot anymore.

Overall this has been great - I'll play with the temp between 205-207 generally I don't go lower then 204 or higher than 208. When pulling back to back shots my following flushes are much shorter.

Don't know if that helps but I know when I first got my machine I read all the forums and searched for vids on flushing tips. In the end it was tasting and doing that made me settle on my routine! Good luck and enjoy the process, the journey to perfection can be frustrating but it's also so rewarding when you get those perfect shots!

In my decade of making espresso, better part with HX, if I have to list causes that ruined my espresso, HX or flushing would be at bottom, rather not even worth mentioning. If fact, I do not even recall HX as a worry or consideration ever. Learning a Simple flushing routine that gives you best espresso is really easy, unless you overthink and over analyze it. Mostly, letting out superheated water with few seconds flush is all you need.
Actually, flow rate is more critical for extraction. I am not talking about variable flow. Even the static flow rate should not be too high.