Boiler flow/vent pipe going crazy!!

[D]

Hi,

From what I've been able to work out, I have an indirect cylinder and pumped central heating system. The problem is that the flow pipe from the boiler into the cylinder (also the vent pipe) periodically rattles like crazy at the top where it feeds back into the feed and expansion tank. Any clues as to what would be causing this? Also, about every 10 minutes or so when the heating is on, I'm getting quite a bit of noise from central heating pipework in the ceiling in close proximity to the boiler - it's almost as loud as if you were listening to the rising main and the cold water cistern filling after, for example, flushing the toilet. Would appreciate any pointers on either of these problems.

Thanks in advance, D.

[John Stumbles]

If it's like a banging noise that could be water boiling in the system. Which is Not Good [tm)

[D]

Hi John,

That's what I thought it might be but I have no idea what could be causing this. I've turned the boiler down a notch or so and it has improved, but it's only started happening recently. Any ideas where the fault is?

Thanks, D.

[Doctor Drivel]

Your boiler stat may be way out on calibration.