We have a central heating system with five radiators and until recently an aging Vaillant combi boiler but this was changed a couple of weeks ago to a Worcester. Since the change the radiators emit a loud rattling hum whenever the boiler fires up. The only way to stop the hum is by either slightly adjusting the TRV or slightly adjusting the boiler temperature - but this is only successful for a short while until the new boiler temperature coincides with the new TRV setting. The very loud rattling hum lasts for maybe ten minutes, and happens frequently day and night.
The installer has connected the inflow through the bottom of the radiators and out through the TRV's. The TRV valves screw directly into the top of the radiator and have a removable Herz liqued filled adjustable head. The valves themselves are about ten years old, and because they screw directly into the top of the radiator cannot be reversed. Please, can anybody give me some advice on stopping the humming radiators and giving my family a good nights sleep.