I pmed Piglet John the other day, who suggested I put on here. In the evening upstairs in one room, we get a loud noise like a vibrating noise. It is only from one area but I cannot pin point the sound. The strange thing is the noise will go away if you turn the thermostat either up or down. I thought I'd also post his reply if anyone has the same problem. We only had the pump replaced less than a year ago too
it might be the pump. Examine it carefully and on the square block where the wire goes in is a speed controller, with settings 1-2-3
Turn it to the lowest setting and see if the noise changes.
If you have a combi boiler you are not supposed to change the speed yourself.
The bearing wear after 20 years or so. If you have a lot of sediment particles in the water (especially if it is, or was, an open-vented system with a feed and expansion tank in the loft, the particles will wear out the pump bearing faster. You can do a chemical clean and fit a system filtr to trap the partucles, but it needs either DIY plumbing or a pro. It does noy involve touching the boiler so you do not need a gas engineer. Try to get recommendation for someone local from friends and neighbours.
If the pump actually seizes up, it will get very hot (hotter than the hot pipes) and will need to be replaced, which is not very difficult. I expect yours is a dull red pump made by Grundfos, they are the best known and very dependable. Cheaper pumps may not last as well. BG will probably supply a Grundfos pump sprayed blue and badged BG.
It might also be pipes vibrating. If you grab hold of them and hold them firmly the vibration may stop. This can be fixed by screwing pipe-clips to the wall to hold the pipes steady. It is an easy DIY job.
or there is a chance it is water squirting through a nearly-closed radiator valve. You can check this by urning each radiator off, then after a minute back on.