Thank you for your answers.
I have to upgrade firmware next time I decide open the front panel of the pump.
Maybe I just forget about those logs in the SD then. It would have been nice to see the difference in operation after I added 180l buffer tank in parallel with the pump. Of course i have a vague idea, how it has impacted, but the actual curves would have been nice touch 🙂
I think that the next thing to do is try to add some analogue measurements to Raspberry Pi. This requires extra add on cards to have the measurements from the heating pipes.