Back in business... I got the thermal break gaskets for the group two weeks ago. Today I installed them and made the first measure. It's an upgrade wich is a great addition for an amazing machine. A great lever got even much better.

If you remember my earlier measures, you probably don't need any explanation. Any idea what measure next ?

The shot took approx. 40 seconds, after which the red line takes essentially 10 minutes to return to the pre-shot temperature of 180 F (the axis says C) without cooling the group. I guess a shot could be pulled after 5 minutes, but it would be about 5 F warmer brew temp - that would effect the flavor (good or bad, depending on how you like it).

The boiler temperature also varies by about 10 F - can you test shots at the high and low end of this range to see how that effects brew temperature.

It would be interesting to see how wiping the group with a damp towel would cool it. It's said that Italian baristas do this in busy bars with lever machines.

peacecup wrote:The boiler temperature also varies by about 10 F - can you test shots at the high and low end of this range to see how that effects brew temperature.

Great idea. I'll do it. Next week is crazy. But after that... Eventually this week end.

peacecup wrote:It would be interesting to see how wiping the group with a damp towel would cool it. It's said that Italian baristas do this in busy bars with lever machines.

I tried this. BUt I think this is a quite aggressive way for cooling the group. Similar to the flushing for heating it. It results in a partial heated/cooled group IMHO. We are not in a busy Caffe, are we ?

peacecup wrote:can you test shots at the high and low end of this range to see how that effects brew temperature.

Made the measures. At the start both of the shots the Group/Portafilter had the same Temperature, 178 Fahrenheit, 12 sec Preinfusion, double basket with 16g coffee grind, and I placed two thermocouples (at the bottom of the basket, and one near the surface of the coffee cake).



First measure, pulling the shot (at the bottom of the heating cycle) at 229 Fh, brewing water (thermocouple near the surface of the cake) stabilized at 196,5 Fh, group at the end of the pull at 189 Fh.



Second measure, pulling the shot (at the top of the heating cycle) at 238 Fh, brewing water stabilized at 202,5 Fh, group at the end of the pull at 192 Fh.



I would say that the temp-difference for the brewing water is exactly the same as the diff of the boilertemperatures. The explanation for the different profile of the second Thermocouple could be that at the first measure the sensor slided back a bit in the fitting (I pulled after that appr 1 mm out).

Cake with the holes made by the thermocouples



I know I should measure next the scenarios with same boilertemperatures and different groups. Let me time for this pls! Have to work and travel . To be continued after Rimini (15th of June).