Unreal!
They seriously pay people to do this kind of rubbish?.
I have the benefit of being in a rather smaller city, if you tried that here as a electrician you would be laughed out of town after the fellas around town heard of it.

in the first picutre, the hot water service has a notice regarding the unit being "winterised". What does this mean?

For summer homes, people often winterize them by draining the plumbing including the water heater and pouring some antifreeze in the traps. That way, there is no water to freeze and burst the pipes in the winter months if the place is unheated. The warning reminds people to refill the heater tank before energizing it to keep the elements from burning out.

What are the yellow tubes? Is this a hot water heating system?

Umm, aren't the yellow tubes usually gas? Very nice to see them snaked along like that. <SARCASM>

NM can't be hung from the bottom of the joists (as is also done here) but gas lines can? No sense. No sense at all. Especially with what looks like that new(er) flexible tubing.

Ian A.

I'd lay odds the owner did this job by searching through a box of old fittings and picking up anything that had vaguely the right ends to get to the next joint. There's even a multi-point manifold in there. That yellow hose looks like garden hose pipe. There's even an automatic air-bleed pot!

Why do rational intelligent people create these death traps in their own homes. I can't see even the local handyman expecting to get paid for this mess, so it has to be a DYI job.