Noise in the central heating

[norfolkboy]

We have a Worcester Combi boiler and

We have an intermittent problem - don't know when it is going to happen!
There will be a noise like a train rushing by and then the downstairs radiators will go off, but the upstairs rads stay hot. If we turn the system off and then on again all the radiators will work.

We have had this problem for approx 4 years and have just had a new valve (Honeywell F4) fitted by a qualified Heating Engineer, the system was then 'bled.' And we thought we had cured the problem - but no - it still is doing it's impression of a 'train.' Albeit not as bad as it was prior to the new valve being fitted. The Engineer was brilliant, but -

We cannot pinpoint the problem (we are asking the Heating Engineer to return). Have you got any ideas

 

[oilman]

If the noise comes from the boiler, it's probably motor bearings. Which model boiler?

 

[norfolkboy]

In answer to Oilman's question -

The boiler is a Worcester Danesmoor 12/14.

 

[breezer]

to save you posting , then some one posting you a question to which you reply see this