My parents had a Baxi Solo3 (60) boiler & circ pump installed and also 3
TRV's fitted to the bedroom rads as part the government grant scheme.
The pipe system is about 30 years old (I think it's the old one pipe
system) feeding 8 radiators in the bungalow. None of the radiators have
lockshield valves fitted, just the radiator valves fitted to one side
only.

Everything is working great and all radiators get hot but the problem is
there's a lot of swooshing noise travelling through the pipework when
the radiator valves are only slightly open or when the system is only on
HW. It sounds to me like there is too much pressure been forced through
the pipes when the rad valves are closing. The pump is on the lowest
setting (1) but still louder than the old pump which was a Grundfos
whereas this new one is from "Circulating Pumps Ltd" - (CP53)

I was reading about the Grundfos Alpha+ pump and was wondering if this
would be a better pump and fix the problem as it automatically regulates
flow and pressure to suit the conditions and eliminates noise in the
system. Any thoughts welcome

TIA