Hi, we have just had a new bathroom fitted, and at the same time replaced 4 old corroded radiators upstairs. This was preceded with a flush (not a power flush) and then inhibitor was added. Whilst the upstairs is now warmer, the radiators through out the house are now noisy (as if you can hear the water coursing through them) and are even noisir if the upstairs TRVs are on any other setting than Max. The fitter returned today and said this was due to the system having being balanced??? The system was pretty well silent prior to this installation. Any thoughts?