Hello!
My central heating was completely reinstalled - new pipes, radiators,
combi boiler etc in 2004, and I've not had any problems with it since
then.

However this winter it seems to have developed an issue whereby the
pipes/raditors are making quite audible ticking noises, which go on
for about 15 seconds approx every 3 minutes. The boiler seems to be
heating the water every 3 minutes, and keeps going for about 15
seconds during which time the radiators make this loud ticking noise
then the boiler shuts down and the noise stops.

The heating system appears to be functioning normally, the raditors
are hot, and the pressure is nominal, but the noise makes it rather
hard to sleep, but mostly because of the worry that there is something
wrong with the system!

The noise is obviously from thermal expansion of the pipes, but it's a
worry when it has never done this before.

Mark