crackling radiators

Whenever our heating goes off, the radiators 'crackle' as if something inside is falling to the bottom. I don't understand this as I thought they were full of water, hence nothing would fall fast enough to make that sort of sound [as you can tell, I don't do plumbing - PCs yes, pipes no!].

Any comments appreciated, thanks.

direwolf said:

Whenever our heating goes off, the radiators 'crackle' as if something inside is falling to the bottom. I don't understand this as I thought they were full of water, hence nothing would fall fast enough to make that sort of sound [as you can tell, I don't do plumbing - PCs yes, pipes no!].

Any comments appreciated, thanks.

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Sorry I cant help but I actually have the same problem and was wondering if you had found the solution yet? [email protected]

Yep, same problem here, although only in two radiators, I've heard several theories, one relating it to thermostatic valves being partially closed, another from the british gas engineer putting it down to thermal expansion in the system! My pump has two speeds and selecting the lower speed does reduce the noise which means its related to speed of water circulation, so it could be that a partially closed valve is causing turbulence in the radiator....but I'm guessing!

blobs of solder/debris