I'm guessing modern.
But...
How do I tell?
The living room Rad is on it's own loop if that's any help.
System was fitted early 80s
no plastic in my house copper all the way.
...mains cable originally spiralled around the CH feed and return pipework (not even laid alongside...no spiralled around and around it)
I think it was in the hope the house would burn down and cover up the hatchet job they made...lol
said hatchet job might explain my bouncy floors...