I am sure you do jobs around your own home like we all do, that you are not trained or qualified to do, but do them because you are confident that you can do the job and to high standard.I am confident to do the water side of the boiler which i have done before 19 yrs ago with no problems since but i know as it stands i would find it extremely difficult to find a plumber to sign it off as he puts his name to the whole of the system,which is fair enough, sounds like a monopoly to me!
Diyers change there own car brakes, which is more dangerous a leaking central heating system or over a ton of metal with no brakes?
I am inclined to agree with muckylugs here.
A few years ago I wanted to fit a living flame gas fire. I was advised all I needed to get the CORGI registered chap to do was the gas side of it.
So, all the stuff like making good the builders fire opening, sorting out the flue etc etc I was OK to do myself, and did so. So then when I tried to get the CORGI fitter whose advice I originally sought to come and connect the pipe, because it was such a small job he was rather non-commital.
So after waiting 2 weeks I ended up connecting the gas myself. To be honest I should add I've had quite a reasonable amount of experience soldering copper pipes anyway, and I made sure I followed the manufactures installation recommendations to the letter, including fitting a gas cock etc etc.
So I know in theory I was a bit naughty, but it seemed my back was pretty much against the wall really, since I couldn't get a CORGI bloke to come out anyway.
I'd have thought the flue side of things was just as safety critical as the gas connection, so like you say it seems there is over compensation for some risks, and none for others.