For back-to-back shots on a 2nd gen La Pavoni Europiccola, my technique emulated what Boren is doing. I toggled power on and off and kept boiler pressure low, in this case at about 0.5 to 0.6 bar. Here's that post. I was using a technique created by Doug Jamieson.

Reaching the Zen Zone with a Two Switch La Pavoni

@drgary - it'll take me a while to do all the tests. So far I only have the initial data from my current setup:



I'll run the same test later today, with a short flushes of hot water a minute before every mark.

As for the 92c reading in the table, it's what I estimate this to mean:



It's more than 90c, but not quite 95c.

The thickness of my heat break (not installed in this test) is 1.3mm

baldheadracing wrote:In any case, my feeling is that the Micro Casa machines ... were intended and designed for a specific use case: Turn the machine on, prepare a couple Italian standard cappa's or espressos, turn the machine off, and get on with one's day. Fifteen minutes total - the Elektra training manual specifies that the MCaL is to be used twelve minutes after it is turned on, which seems about right for an Italian espresso blend.

My experience with the new-to-me 2013 MCAL matches the quote above. Mine is set at 1-1.2 bars and I turn it on only when I need it. Turn on, wait 10-15 min, group and steam purge, 14gr of Redbird = really nice double ristretto. If I forget to turn it off - way too hot.

Edited after measuring this morning: 12 min worked really well, including purge steam and group and wait until the pressure builds up again (which takes longer after the first purge, possibly due to false pressure or maybe just the colder temp.) Used cold portafilter (left on the counter until used.) Tasty.

I am still confused about all this.
Below is a photo of my Microcimbali from this morning's brew at work.

Yes, that is correct 103C at the group.Yes it is lower than the 108C calculated by the 1.3bar boiler pressure but it is still way north of 93C.
I also purged the boiler water through the group into a warmed cup (not hot) and the water temp was 97C
The shot was great????

You're measuring the outside temperature of the group, which apparently exceeds the temperature in the brew chamber, where the coffee at room temperature rests inside a portafilter and basket that are also cooler than the outside of the group. Nice looking Microcimbali, BTW.

@boren: It's hard to tell what your temp is in the brew chamber. Notice that the temperature strip higher on the outside of the group is hotter than the one just below it, where the 90C tab is just starting to get activated. In any case, I'm glad you're measuring yours.

I think we are also comparing different techniques, though. When I pulled multiple shots in a row I would cool the portafilter. I believe you want to just lock in and pull without overheating. Also people can avoid overheating for a few morning shots and then power down.

So I think the premise of this thread is not an absolute but also a matter of technique.

As an analogy, people often complain that La Pavoni home levers aren't temperature stable. I like their ability to warm up quickly and temperature surf by applying methods to heat or cool the group for a particular coffee.

drgary wrote:You're measuring the outside temperature of the group, which apparently exceeds the temperature in the brew chamber, where the coffee at room temperature rests inside a portafilter and basket that are also cooler than the outside of the group. Nice looking Microcimbali, BTW.

No I am not trying to hijack this post, and we are trying to understand the same basic issue.
Thermodynamics tells me that the water temperature inside the boiler must be greater than the external temperature of the boiler surface. The only way to be absolutely certain is to measure the actual temperature of the water as it would enter the brew chamber. I drilled a hole in an old double walled basket and used a thermocouple to measure the temperature at the point it contacts the puck. Hense I am still confused about trying to achieve a brew water temperature of 93C

Tim,

I think your question is relevant. I see that you are only measuring the temperature of the water as it exits the shower screen into the brew chamber. But, you are measuring without the usual load of coffee there. What is the measurement inside the coffee cake itself? The coffee will cool the brew. I have done my measurements that way.

Well Well Well!
Just shows you need to get the data! I was surprised that it brewed as per normal and no leaks. The shot was great as normal.

Thanks for following up. From here, you can pretty much trust what you taste. If you were brewing at too high a temperature it would taste like it. Sometimes I'll dial in by brewing a coffee in an immersion brew with something like an AeroPress. I'll adjust my shot to taste like that and will correlate that with the readings I get outside the group to adjust for what's happening in the brew chamber.