Worcester Greenstar Junior 28i vibration/rattling/grinding

[One74255]

Hello knowledgable people! After searching this forum and googling a lot I still don’t know exactly what could be causing this:

https://youtu.be/Lfj3YZE_z60

I will of course call someone to sort it out in the end, but I read quite a bit about some less-than-perfect people wanting to replace the whole thing quite unnecessarily, so it would be great to have an idea of what can be the problem!

Some observations:

The noise propagates quite loudly through the radiators in the house.

I did the basics: bled the radiators, pressurised to 1.5 bar, emptied the sludge from its trap.

Nothing the hand can easily reach feels like it is shaking or vibrating.

The noise can be still heard when the green gas light is off.

I tried disconnecting power to the fan and the noise was still there with the fan off.

What do you think will need to be done here? Thank you for advice!

 

[muggles]

You shouldn't have the casing off your boiler, it forms the safety room seal and should only be removed by a Gas Safe Registered Engineer. Could be something stuck in the pump.

 

[One74255]

You’re spot on, it is the pump. Reducing its speed from 3 to 2 makes the noise go away.

Good for now, but I will have it looked at.