I've just done a underfoot heating job for an ex high school chemistry teaching who now sets and marks exams. Though to be fair he was not a bad fella, he was such a nuisance that I ended up loosing my rag with him.
He wanted to be "hands on" constantly interfering with the install. I bit my lip for way too long and humoured him throughout "can I make a suggestion" was his favourite term.
It got amusing but annoying at the same time as he was always hovering under everybody's feet. He spent his evenings down loading and studying how, underfloor systems work, the do's and don'ts and everyday "he had a suggestion" which I often replied with "I have done this job for years you know, and installed umpteen heating systems".
Anyhow right at the end of the install I fitted the thermostatic controllers and proceeded to program them. At this point my customer took over, as he had studied the manual and would show me how to set the programmers up.
I left him too it, collected my tools up and hit the road. Next day I had the call - "these controllers are faulty, I've set them up but they don't work properly. Can you come over and replace them"
You know where this is going!
He remained adamant that He had programmed them correctly and that they were a poor design.