On 16 Nov, 13:47, "john east" wrote:
A year ago we had a worchester Ri boiler fitted on the wall in our kitchen
diner. *It's always made a bit of a banging noise. Not every time, but
really quite often; usually just after it turns itself off, after the boiler
being on for a bit.

We have just had our first annual service. The chap never even opened the
boiler, but just fed a meter tube into the top of it and he also watched how
fast the gas was going out of the gas meter.

I asked him about the banging. He asked if the rads had been bled recently
and I confirmed that they had. Since it was suggested to me that this might
be a cause of all the rucus. *After looking in the water cylinder cupboard
he told me I needed a 'by pass' or a 'mixer valve', but looking at it he
wasn't sure where the by pass pipes would be connected.

Are these 'by pass' and 'mixer valve' not items that should have been put in
when the boiler system was installed last year?

I had a new Worcester 24ri fitted a couple of years ago and specified
an auto bypass valve to be fitted. After installation I got the same
banging as you and on further investigation realised the valve was
never opening as the adjustment was incorrect. So effectively it was
like your installation. After adjusting the valve no further noise.

John