Vokera Linea 28 - rattling

[blackboilersuit]

Hoping somebody has come across this before...

We have a vokerra linea 28 combi boiler. Functions as it should but rattles something terrible. Thought it must be a shot bearing in the pump but went investigating with a screwdriver to the ear anyway. Pump sounds ok, motorized valve sounds ok. Sound appears to be coming from the DHW heat exchanger. CH is bled and pressure ok at 1.5bar, whole system under 5 years old so no sludge (rad water comes out clear) and we have no issues with scaling in our water supply. Rattle present when generating hot water only or when CH only is on. Also present when CH on regardless of whether burner is on or off.

Any ideas? I didn't think a heat echanger could rattle?

thanks in advance for any ideas you can offer

cheers

Stewart

 

[Agile]

It could be something loose somewhere inside a waterway like a screw.

I think that your boiler has a built in bypass pipe at the back. These have a spring loaded pressure valve which opens at about 1.5 m head. Sometimes these rattle on the seating, perhaps caused by a weak spring.

If this were the cause then its often when there are TRVs on every rad or the user turns off the rads thus stopping any flow and causing the bypass to flow.

Tony

 

[Slugbabydotcom]

Do you think it could be the fan?

 

[scatmanjohn]

It will be the cheap crappy non return valve. (changed plenty)

If you look at the hw heat exchanger from the front, its in the top right hand connection.

Change it and your rattling woes will be no more

 

[blackboilersuit]

Big thank you to you all for helping out.

Pretty sure scatmanjohn has the right answer with a rattling non return valve. All the checks i've done point right at the area where the non-return valve is located, I just didn't realize it was there as it's inside a fitting. Guess I should have thought about it some more and paid more attention when I looked at the exploded drawing.
Will order a new one up along with a few new sealing washers but think I'll leave the replacement till the weather gets a little better and we can do without the heating for a day.

cheers again

Stewart