Combi boiler noise: low flying plane to elephant

Hello

Had a new rad fitted in my flat, since then the boiler has been making noises on CH startup and HW usage. CH startup getting worse..at first I honestly thought a plane had flown over my house (about 3 seconds of noise)..now it sounds more like a really sad elephant (about 5 minutes of droning and wailing).

Noise stops when I call HW

Boiler is a precondensing Vailant turbomax 824

I (not an expert) think sediment has somehow got into main heat exchanger..

Just wondering if

1) the game is up - need a new HE
2) this could have somehow been avoided in rad fitting if the system had been drained/filled differently?

Thanks. Feel sorry for my neighbours at the moment when the elephant starts at 630am..

what does a sad elephant sound like?

may you can make a video / sound clip and post it on youtube so we can hear for ourselves

Unfortunately it does sound like **** in the heat ex, i have actually experienced it on the same model myself after recharging an expansion vessell dislodged some muck and caused the aeroplane/elephant noise,
Putting chemicals in the system and giving it a flush may work.

With point 2 i hope you dont feel you need to point the blame to whoever fit your radiator, its not his fault if hes dragged muck through on drain down.

A sound clip or vid would help diagnose it with more accuracy.

If the noise stops when you turn a tap on it could be a diverter valve issue.

Thanks for the replies. I'll make a vid so you can hear a sad elephant in action..

Yep - not trying to allocate blame, geezer who fitted rad was really sound, just wondered out of interest if there was a cunning way to do this on old systems without causing crud to travel to the HE (eg: refill really slowly? drain in certain order etc?).

Ive put some cleaner in and we'll see how it goes..

Could be diverter - from what I can see its still the original part. Having said that - I get CH when I want it, no random CH when I just use HW etc.

Thanks again for your replies - this place is flippin great.