HELP - Hot water pipes humming

[farthings]

Hi apologies if this has been covered but I can only find examples when people have a header tank. We have a problem with a humming noise that's omitted when we run the hot water.

Generally it only happens with the showers (the noise does go away when the flow rate on the shower is increased) although it has been known to happen when using the bath and very occasional one of the bathroom sinks.

The system is a pressurised unvented hot water system incorporating a Viessman Vitodens 100-W boiler and an RM cylinder.

The hot water tank is in the loft and the two bathrooms are fed independently of one another via pipe drops into the bathroom areas.

If anyone is able to shed any light as to a cause and possible solution it would be much appreciated.

Many thanks.

 

[45yearsagasman]

It may be a pressure control, or maybe a mixing valve causing a noise. Not being on site is difficult to be more precise. Any repairs on unvented should only be done by someone with G3 ticket.

 

[farthings]

Many thanks for the prompt and helpful reply.

The whole install is relatively new (complete house renovation) and the plumber rates amongst the better tradesmen I've encountered so I'd look for him to do any fault analysis / correction anyways.

The primary reason for the post is that I like to try and have an understanding of what I am asking someone to do / fix.

Sorry for being a bit of a layman but can I clarify but does the pressure control form part of the cylinder set?

As for the mixing valve do you mean the one fitted to the showers (Aqualisa) and the bath / basin taps (bristan) themselves as the noise appears to come from higher up in the system?