I'm guessing that is a reference to Omid Djalili sketches about Polish plumbers:
* https://www.youtube.com/watch?v=K85ZtXnMxbM
* https://www.youtube.com/watch?v=P8mjzu0Runo&t=1m
* https://www.youtube.com/watch?v=_FM9Ps6cW9U
* https://en.wikipedia.org/wiki/Omid_Djalili
Anyway - I just added a valve regulation to our kitchen floor heating this weekend, so it was not only joking :)
I'm guessing that is a reference to Omid Djalili sketches about Polish plumbers:
* https://www.youtube.com/watch?v=K85ZtXnMxbM
* https://www.youtube.com/watch?v=P8mjzu0Runo&t=1m
* https://www.youtube.com/watch?v=_FM9Ps6cW9U
* https://en.wikipedia.org/wiki/Omid_Djalili