I do handy work on the side (literally anything I can get my hands on) and there was this woman who basically told me:

"Listen, I want you to do the job, but you're supposed to my way, I know how this works."

The problem is, if I did it her way it would break the boiler (I.E: I'd have to pay to replace the unit). This of course doesn't take into account possible injuries or property damage (E.G:, if it falls and destroys the wall/floor).

I got up, packed my stuff and gave her a full refund (on video) then walked out of the door (the entire interaction was recorded by my body-cam).

This was yesterday and I've just got off the phone with a friend who told me about how some poor schmuck fucked up, broke the thing and now has to shell out +(2-4)K to replace the entire unit + piping.

Please don't try to please an unreasonable person by doing illogical things.