"David W.E. Roberts" wrote in
:

There should be at least one central heating FAQ floating
about. Try http://www.diyfaq.org.uk/ for starters.
No doubt the plumbing pros will point you to more resources.
HTH
Dave R

I was going to refer to the faqs, David, but there appears to be nothing on
this item there;

chance for someone to get famous? I would, but my knowledge is pretty
d-i-y, (IYSWIM)

mike r