How about appreciation? This is a great contribution!

I also would like to take this opportunity to thanks drgary' great contribution on HB here

I've edited a new graph again. Made the measures with the recent Cremina. Yellow: Boiler temperature 248F (average, because of idling), Group temperature just before the pull 178F. Blue: Boiler 248, Group 172F. Green: Boiler 237 Gruppe 178F. The graphs show the three different temp profiles of the brewing water (measured in the chamber).



The results are logical and known I think. The temperature of the brewing water is determined primarily by the group temperature. The boiler temperature is secondary.

The average temps during the pulls (after 10 sec pre infusion, that means the last 40 seconds) are as follows: yellow 195F, green 192F, blue 188F.

As a small extra I've made a small time lapse video for members with a temperature strip on the grouphead :

How accurate are temp strips: time lapse video

This is a wealth of data and is going to take some time and effort to apply it to the LaPavoni. Great work!

Thanks Rich! Yes, too much data to be honest. I logged tons data and now it is really challenging to find and process the interesting/important series .

Anyway I've found a log about a cooling run with a wet towel after a single pull. I can remember how surprised I was that the cooling of the group can be done in less than 2 minutes. The surface/body temperature of the group to be precise. The piston and the piston rod are a way behind. I know that there are other methods of cooling also. Using a cold pf for example or pulling cold water into the group. Though this last one not the most effective way for bringing the temps down because at the downstroke we are pulling fresh hot water above the piston which clearly overcompensate the intended cooling effect.

I think it is maybe usefull to share the group temperatures after a long (1,5-2 hours) idling periode of the different Creminas and the Club. For me is ideally this temperature slightly lower than the target group temperature for the pull. That means I can reach my target with a quarter or even shorter pull easily and the recovering time is way shorter if I want to pull a second shot.

I set the pressure the same (0,9-1,1 bar,boiler temp: 245-250F) to get comparable grouphead readings.

Olympia Cremina '67 without teflon gasket: 194F

Olympia Cremina '67 with teflon gasket: 180F

Olympia Cremina recent model: 172F

Club without teflon: 183F

Club with teflon: 169F

That means for me a lower ideal boiler temp (232-239F) for the "teflon" Cremina '67:

Olympia Cremina '67 without teflon gasket: 183F (still to high for my taste)

Olympia Cremina '67 with teflon gasket: 171F

Feel free to share your thoughs and experiences about this topik.

Cheers

Gábor

Very interesting and useful. The only limiting factor for the average user is not being able to meassure boiler pressure/temperature.

You can get a steam wand pressure gauge to preset your boiler pressure. These are easy to construct from common parts in a hardware store and instructions are found with a Google search.

Katoci wrote:Very interesting and useful. The only limiting factor for the average user is not being able to meassure boiler pressure/temperature.

Or you could ask your local lathe machine engineering make one boiler adaptor for you. I just have mine locally here and the price is quite cheap.

naked-portfilter wrote:
I set the pressure the same (0,9-1,1 bar,boiler temp: 245-250F) to get comparable grouphead readings.

Olympia Cremina '67 without teflon gasket: 194F

Olympia Cremina '67 with teflon gasket: 180F


Gábor

Dear Brother Gabor, My Cremina 67 set in 0.8 Bar without Teflon gasket ) idling was around 185F