Hi, about 3 weeks after overhauling the diverter and diff valves with valve and seal kit, the noise started to occur seemingly from the diverter although it's difficult to pinpoint exactly. The noise starts a few minutes after CH is activated, and is persistently loud and is carried through pipework to radiators. Opening a hot water tap stops the noise immediately only to return a minute or so later. Also, fully opening all trv's stops the noise, very significantly but not entirely. Any advice is very welcome and appreciated.