On 21/10/2013 19:01, Peter Crosland wrote:

That brings us back to the 'competence' problem of not being defined.
Just because a building blows up it doesn't provably mean that
anything about the installation process was incompetent or negligent.
Boilers, etc, carry warranties for this reason.

After I had my previous system installed, a leak developed in the
joint on the supply side of the meter, which the installers hadn't
touched. Buildings blow up for reasons other than lack of competence.

Of course not but that is not the point. Anything burning has an
inherent risk of danger. Explosion is only one of the potential dangers
that can occur by incompetent work. There are far more common risk of
poor combustion is CO poisoning. Do you think it is acceptable to put
people's lives at risk by trying to save a few pounds?

Which is the higher risk : DIY done competently or professional done
incompetently? There's plenty of examples of the latter in this thread.

This stuff isn't magic. It's entirely feasible for somebody to DIY stuff
competently.