Long time lurker, but first time poster. Lots of info that had truly helped, but this one I'm truly stumped. Maybe if pigletjohn strolls along.
Since the start of the year there has been an incredibly short but loud vibrating hum in our central heating. It's intermittent, and the radiators actually shakes from the vibrations, it's that loud. We cannot ascertain which rad or where it's coming from; as the sound is usually less than 30 seconds it leaves us running room to room to try to figure out where it's from. It's feels like it's the loudest in the master bedroom.
We started the process of elimination to isolate the source, from the investigation the past few weeks it felt like if the lockshield side of the master bedroom rad is fully off, the sound happens, albeit still intermittently. When the lockshield valve is open, the sound/hum doesn't happen.
What could this mean? Is the fix just to replace both lockshield and trv valves? I am wondering why the sound is happening when the lockshield is off, is it because the radiators are in parallel and a radiator further from the boiler calls for heat, this forcing hot water though the junction where the "defective" lockshield is causing the vibration?
We did call a plumber, but as it's so intermittent it's hard to reproduce the issue when he's here. According to the plumber, sound travels really well as copper is a good sound conductor. And the only thing that can cause the sound are the valves. I don't want to keep calling him back to replace valves one by one. Maybe it's much better to replace all the valves in the house now? Too big bang?
Thanks so much in advance. From a sleep deprived mother who is woken not by a toddler, but by a very noisy central heating system.