Shrill noise from central heating

I am getting a phone like noise emitting from the Cupboard where my Vailliant EcoTec boiler is installed.

The boiler has been checked by Vailliant and nothing was found.

The noise is intermittent.

The Condenstat has been changed due to horrible noise and while that noise was cured the phone like noise still occurs.

I Have a Digistat 1RF Thermostat working with a DigistatSCR.

Alongside the SCR is a Honeywell ST9400C Programmer'

Close to the Cylinder is a small unit labelled as V4073A1039 Do not know what this is.

Any help regarding the reason for the noise would be appreciated

Could be a struggling motor in valve. 

Tom78 said:

as V4073A1039 Do not know what this is.

Click to expand...

Thats a Motorised Valve ,   it could be making the noise .  

Does this happen when you are switching the heating on or off? Do you have a pump on the pipe work? It could be air passing through the pump causing it to run dry. 

How good are you at following instruction? 

Sharpend 

Thanks, i dont follow instructions very well, nearly 80. The most recent suggestion from both yourself and Evans Electrical  re sticking valve looks promising.

would it be a job for an electrican or a plumber?

Tom, can you look at the pressure gauge on the boiler and let us know what it says? 

The only visible gauge on the boiler, Has a display showing two symbols, and I assume is a temperature reading.

on the right is a sliding scale with bar at the top which I am assuming is the water pressure. The scale has an upper and lower points and is currently near the upper level but in between the two limits.

Is there a pump near the cylinder tank? 

Yes there is. 

A PRO 135430 Condensate pump which was replaced recently due to sounding it was going to fall a part, and is quite now and  a IntaKlean IKMF22 or IKMF28.

None of this appears to be effecting the performance of the system just making this noise.  Worried it maybe dangerous.

That is just to remove the condensation from boiler? Is there a circulation pump like this https://www.google.co.uk/search?  ?

Yes there is the InstaKlean looks just like that only black

The instaclean is it like this http://www.intatec.co.uk/document/496/Technical_Data_Sheet_-_IntaKlean_2_Magnetic_Filter.pdf

if so that is a magnetic cleaner keeps water soft. 

can You take a pic of the cylinder and associated pipes? 

Yes exactly that.

cannot load pic max size allowed is smaller than I can create.

You will need to use a tool for uploading pics, perhaps one of our members could advise? 

might just be air in system, have you tried bleeding the radiators lately?

I suspect it is air passing through the pump, a bleed of the radiators and pump should sort it. 

Thank you both

will bleed radiators in morning 

Shrill noises can be instigated by kettling, loss of water or air is stuck inside your system. If it is trapped air, you can simply fix this by bleeding your radiators. ... When they bleed your radiators, they'll also find out what caused air to become stuck in the boiler and accomplish the suitable repairs.

But before doing this, you might want to have a service specialist come out to inspect your system, who can physically hear the sound that your radiators are making and examine your system.