I have a quiet knocking, coming from somewhere in my house, I think we have located it to a corner of the house. I innitialy thought it was a knocking in my steam pipes (we have cast iron radiators) but not sure. It is not the typical ping I am used to when the radiators kick on, or the the metallic klangs, that we sometimes hear from the pipes. It seems a like a dence solid sound, knocking in succession, getting quicker as it goes along, then slowing, almost like knocking on my desk.
One of the times I heard this, the pipes were hot, the next time the pipes were cool. Any adivice would be great.
Thanks in advance.