Thanks for your reply,

I had to re-hang one of the radiators the other day so emptied it first and
the water that came out was clear apart from the very end when some black
goo seeped out.

The CH system is about 4 years old, so is this normal.

Thanks,

Andy

"David W.E. Roberts" wrote in message
...

"Andy Turnbull" no email please! wrote in message
...
Hello,

In a closed CH system where everything is new (boiler, pipes and
radiators)
is it possible to still get a build up of sludge in your radiators and
if
so
how?

Yes, if you don't put corrosion inhibitor in the water.
Probably happen faster if you don't flush out the acid residues from
soldering.
Even so, it should take some time for an appreciable build up of sludge.
If you bleed some water off from a radiator and it is black, then this
suggests corrosion and sludge.

HTH
Dave R