Problems with unvented hot water suystem

[Snigie]

had a similar issue on a unvented cylinder, the problem was the diaphragm was resonating in the vessel because it was upright like in the picture, the manufactures advised me to mount the vessel in the horizontal position.
it doesn't sound like it would make a difference and i don't understand why it would.
but it did work and i now never mount them vertically.

 

[Snigie]

just to add. the noise only happened first thing in the morning. and can't remember for the life in me what the tech advisor said was the cause.

 

[neiltheplumber]

I would go with the prv!

 

[vics99]

Thanks Snigie. But the thing is, the cylinder has been in the house for 20 years and this problem only arose five months ago when they changed the boiler.

However, it does seem to be the case that the noise only occurs first thing in the morning. Or -- more specifically -- it seems to occur when my wife takes her shower, which is first thing. We don't get problems at other times, but maybe that's because there's nobody in the shower.

 

[Scubamem]

Did this ever get resolved, as I have exactly the same problem. Only seems to occur when a shower is run first thing in the morning.