Vokera linea and radiators whine loudly when hot water cease

[redcurrant]

I have a Vokera Linea 24, which was installed about 6 years ago, with a majority of new radiators, but I think the pipes were kept. I don't think it was desludged. Last summer a plumber came and said it all needed desludging because it was starting to corrode, so I had this done. He said it might need redoing in 6 months, but when I rang him he said if it was operating OK then there was no need.

Meanwhile, however, it's starting to whine usually when I've used hot water and I turn tap off - it's the cessation of hot water which starts the whining. Sometimes it gradually fades, sometimes it gets louder. The whining comes not only from the boiler but also all the downstairs radiators. The pressure gauge reads OK. I'm worried in case the whole thing explodes!
(It's whining/loud moaning - def not rattling or banging)

To stop it, I usually have to turn off the central heating - not good if the weather's cold. Sometimes not even that works. Very occasionally, the whining will appear when I haven't touched the water at all, but then it's not as loud.

I called him out once to hear the noise, but sod's law - it didn't happen when he was there, and he seemed not to have any idea what it was.

I've noticed various noisy boilers on your postings, but they all seem to have different causes. Can you diagnose probable cause here? Thanks!!

 

[scatmanjohn]

Could be a diverter problem. Try getting it refurbished.

I have had a few with this problem but its hard to tell without hearing it.