I am taking his word that he has installed UFH, and I have no reason to doubt him. I was a little disappointed when I mentioned the circular layout vs meandering layout (
like this image shows) and he said he only does meandering. But to be fair to him, I find lots of information on the internet saying circular is best, but then I also see lots of photos of the meandering pattern - it's hard as layman to know which layout should be used.
I assume it will be this way, but he asked if we wanted diffusers ... so I guess he wasn't assuming screed.
I may have approached this incorrectly by just saying "we'd like UFH those rooms" as there are so many ways to do this. I wrongly assumed that UFH was just pipes in screed.