Central heating loud rumbling noise

[Daf10]

Please help.

For the past 12 months we've had a horrible 'clunking' then rumbling noise coming from somewhere within our central heating system. We have a 2 port valve above our combi boiler that seems to make a loud 'clunk', but the rumble seems to be coming from under floorboards whenever a TRV reaches temp and switches off, or the main room thermostat hits temperature. It has become unbearable over the past 2 weeks and is now waking everyone up in the house. I've managed to film the valve switching off so the 'clunk' noise can be heard (struggling to attach the file, will try and upload later), followed by the rumble but this is much quieter and less 'fierce' than usual. The rubble almost sounds like its coming from everywhere under the floor. The noise is at it's worst about 5:00 in the morning.

I should add there's another valve in our kitchen near the UFH pump and this also makes a quieter 'clunk' and rumble.

We've had 3 plumbers look at it so far but none have had any luck solving the problem.

Please, please, please help if possible

 

[Gasplumber]

Without hearing the noise it’s hard but if you’ve had 3 plumbers around maybe get a big name firm in

 

[Daf10]

I've uploaded the video onto YouTube so hopefully this link will work???

If you can have a listen/watch that would be great

 

[Alec_t]

Sounds like rapid closure of a valve, resulting in a water shock wave causing vibration of a length of pipework. Vented or sealed system?

 

[Daf10]

It's a combi boiler on a sealed system. I hope that is right!

 

[Alec_t]

Well that rules out the float-valve on a F&E tank as a possible culprit.

 

[Gasguru]

What's the boiler model?

 

[Daf10]

Worcester 32cdi

 

[Daf10]

I've now attached a pic of the UFH pump setup. This also 'clunks' and rumbles when the thermostat gets to temperature and the valve switches off, but it's not as bad as the main valve above the boiler.

Can it be the valves since the noise happens when they switch off? The 'clunk' sounds like it comes from the valve but the rumble sounds like it's comeing from everywhere under the floorboards. One of the plumbers who's looked at it has mentioned he couldn't see a bypass???

Any help is much appreciated.

 

[picasso]

Seems one of the plumbers got it right, you need an automatic bypass installed before the zone valve above the boiler.

 

[dilalio]

Yep. My money is on lack of auto bypass in the right place.

 

[Daf10]

Thank you. This is good to know.

I've attached another pic. showing the room available above the boiler. I'm guessing they didn't installed a bypass because things are so tight???
Would the bypass above the boiler stop the 'clunk' and rumble from the UFH pump?

Is there a temporary fix I can do until we're out of lockdown?

Thanks again

 

[picasso]

Are there any pipes under the boiler ?

 

[Daf10]

Lots

These pics any good?

 

[picasso]

It looks like you have a flow and return under the boiler, still a bit tight but doable.

What part of the country are you in ?