Hi,

Recently I bought a Bezzera Magica with built in PID controller. The temperature can be set between 80°C to 100 °C (176 F - 212 F). As far as I understand the system, the PID sets the boiler temperature and the temp. shown on the display is a CALCULATED temperature at the brew group, based on the boiler setting. The user manual does not provide any useful information, please correct me if my understanding is wrong.

Am I also correct that a cooling flush is still necessary, same as with a machine using traditional pressostat control? I guess that after some idle time the water in the heat exchanger is much hotter than the shown temperature on the PID display, which I believe is only a theoretical value, based on the boiler temperature.

I have also heard the statement that a PID controller on an HX machine is actually useless, contrary to single or double boiler devices - any other opinions on that topic?

I think the flush would still be necessary, I have heard the pid isn't needed but I'll leave that for someone else to comment. The HX tube would get over heated, so a flush would still be need from my understanding. I steer clear of electronics when I can, I prefer a little more seat of the pants espresso...

No flush is needed since the boiler temperature is set to deliver the desired brew temperature using the PID as you describe. Technical specs for the Magica don't show PID control, so this looks like an aftermarket modification to control brew temperature. At these low boiler temperatures (to achieve a brew temperature of ~201F) you won't be able to steam very effectively.