Just recently we have started getting intermittent water hammer from the CH
pipes.
It's an old system, at least 25 years. New World backboiler, pumped ch,
gravity dhw. Serviced annually
and works well enough. (yes, I know it's time for a change).
The noise always comes from the same place, under kitchen floor about 2m
from the boiler. I presume this is the return to the boiler and probably
the lowest part of the system. AFAIK the pump is between the hammerpoint
and the boiler
Any ideas for a cure please?
I am thinking it may be a build up of sludge/muck. If so, what do I do
about it?
System hasn't been drained for a couple of years and inhibitor was mixed in
at that time.
Touches wood ~ heating continues to be ok.

Thanks

Nick.