Good afternoon

I have a gaggia classic pro recently acquired. I read a lot to try to understand the temperature process. Then from some youtube video I saw someone with a cheap thermometrer installed in the gaggia. It was nice to have an option before spending money in a PID.
Then I bought a cheap thermometer and measured the temperature at the boiler wall and at the grouphead. I made some test to identify the temperature range for my shots. I'm happy for now with the results.

Here the graph temperature obtained with the thermometer



You can see in the graph the time cycle in min:sec in the horizontal axe, the temperature in celsius degrees in the vertical axe. The blue line represents the temperature variation at the wall of the boiler (inside the machine) once the machine is stable. The orange line represent the temperature variation on the wall of the grouphead. And the grey line represents the temperature variation at the wall of the bopiler when I made a espresso shot.

As you can see the temperature at the boiler is much greater than on the grouphead. This is because there is a flux of themperature from the wall of the boiler that cross the water inside and finally reach the gouphead. There is a lag of the wave of heat form the boiler to the grouphead. At the grouphead the temperature is much more stable (92 to 96°C) than at the boiler (96 to 108°C). But I have notice that there is steam inside and that is because the temperature at the boiler reach 107°C.

Then I want to get my shot at a 94°C at the grouphead; this is around 100°C at the boiler. I'm monitoring the temperature at the boiler because at the grouphead is unconfortable. So using my cheap thermometer I can roughly surf the temperature wave downhill at 100°C to make the shot. I always run some water to free the steam before the shot.

Here the thermometer I got from Amazon:

https://www.amazon.com/Thermometer-Inst ... 081HXD2WP/

Hope this can help to get better shots

Cheers

Victor