Do you turn off the heating completely during vacation?

The question refers more to the months of June [August]. I leave the heating running.

March or August doesn't matter... you can just turn on the frost protection mode when you leave, it's basically the same as the holiday function

The question rather refers to the months of June and August. I leave the heating on.

If you read carefully, the heating itself is not the interesting part for the OP, but the unnecessary provision of hot water. : Have you checked if your heating system has a vacation mode; or how old is the heating system?

Depending on how long the vacation lasts, I would then do a thermal disinfection. If the temperature stays between 40 and 25 degrees for days, these are ideal conditions for Legionella bacteria.

Depending on how long the vacation lasts, I would do a thermal disinfection afterward. If the temperature stays between 40 and 25 degrees for days, these are ideal conditions for Legionella bacteria.

But the heating system, at least the ones I know, does that weekly...

I am pretty sure that my heating system does not have a holiday mode. Since we have traveled/flown on vacation in spring and autumn in the past years, I lowered the flow temperature by 5°. That way, it would only turn on in really cold weather. I was less consistent with the hot water. Depending on the length of the vacation, I let it run, lowered it, or turned it off completely. However, our heating system does not have a hot water storage tank. Therefore, it is only partially comparable.