Horrible screeching from cylinder?

[ahmedel]

Recently this horrible screeching noise has been coming from the cylinder. The pressure is fine and all the heating controls (Vaillant VRT350) are normal too. We've not had heating from the radiators upstairs since this has started too. The noise seems to be coming from the box on the left at 00:10 which I believe is the motorized valve? It wouldn't let me upload it here, so here's a link to the video https://imgur.com/4vJxJXc

Does it need to be replaced?

Any help would be insanely appreciated

 

[ianmcd]

That is not a MV noise that is a pump noise

 

[Madrab]

+1 , agreed, that sounds awful like a pump that's very close to destroying itself.

Is there a space under the unvented cylinder cupboard, if so the pump may be located in there, which is why it's louder when you move over to the 2 port valve and the pump's below that.

 

[BoilerBob]

Sounds like a pump running dry or air locked. Bob