Hi,
I've just moved into a new flat and when you flush the loo, the pipes under the floorboards make a very loud groaning sound, with some vibration, which goes on for the period that the cistern is filling up again. The flow of water to the cistern doesn't seem to be affected. I assume this is an air block of some sort? What can I do to get rid of it?
Thanks.

Edward Sanderson, October 2006

it is the valve in the cistern worn inside and vibrating. flush cistern and hold valve you will feel it.its quite cheap and easy to fit new valve

N. Mallett, October 2006