sound!

[CXR100]

i have a job that customer is complaining about sound coming from rads, its like a circulating sound, system is around 20 yrs old , but boiler is about 2 , (worcester combi gas) boiler enginner has changed the pump, sound still there, when you close th trvs right down the sound disappears, or when yu open hot tap, but i gues this is because diverter valve is now open to hot water right???? , does anybody know what it is??? im not gsr so canot do nothing to the boiler, but do you reckin its something else??? the trv's or something???

 

[CXR100]

P.S no comments about re piping it in sqaure pipes please

 

[stoker122]

Possibly lock shield valves closed down too much, try opening them all fully (taking note of how many turns so you can set the back) and see if the sound disappears.

 

[CXR100]

they are fully open! all of them! the boiler engineer metioned a power flush??? would this cure it??