Since having a new Baxi boiler, pump and 3 TRV's fitted we've noticed a lot of swooshing noise that reverberates throughout the radiators and pipework, very annoying at nightime. There doesn't appear to be air in the system but I think the noise is caused by the pump. It is a "Circulating Pumps" (CP5m) with 3 settings. Increase the pump speed and the noise gets much louder but left on the lowest setting it is still excessive and seems to get worse as rad valves close. We were told to have an auto bypass valve fitted (which we did) but that hasn't made much difference. When the boiler is off the pump keeps going for 8 minutes (which I believe is normal) but during this time the swooshing noise gets worse but turn the pump off and the noise stops.
I was wondering if the pump could be too powerful for the system as even on the lowest setting the rads get hot? Or is there a better pump that would be better? Thanks.