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?