Boiler making weird noises

[khanm]

Hello All, I am wondering if you can please guide me here.

I have a vaillant boiler and it makes weird noises when its starting. Its not all the time but mostly does once a day. I have attached the video.

I usually turn off / on the boiler and the sound stops or
I turn on hot water tap (kitchen or bathroom) and this sound stops.

Any help will be appreciated.

Thanks

Video: https://streamable.com/n0cikr

 

[CBW]

That’s a flying insect trying to escape joking aside, it should be a simple job for a gas safe registered engineer, as the case forms part of the combustion circuit.

 

[khanm]

That’s a flying insect trying to escape joking aside, it should be a simple job for a gas safe registered engineer, as the case forms part of the combustion circuit.

lol and thanks.
Just wondering what work would that be so i can do estimate of costs.
Regards

 

[CBW]

It needs the diverter valve replacing.