Noisy bypass valve

[TerryWaite]

I have an s plan system with an unvented cylinder and a radiator circuit.
For the last month or so, when the 2 port valves shut, but the pump overrun is still running, I hear a vibrating noise coming from the bypass valve / AVDO.

It sounds like water struggling to get through the valve/ resistance to flow type sound, not really loud but loud enough to be a nuisance.

It is a new build house, system was put in less than 2 years ago. Never had problem before, it is not a danfoss valve I think it may be a cheaper version. It is an angle type one not the in line.

Anyone come across a similar problem with a bypass valve?

 

[lame plumber]

yep, when it is fitted to close to the boiler in situation such as a boiler and unvented cyl both in an attic and everything is very compact and no decent length of pipe to valves and bypass hums and bangs when ch valve shuts down and leaves only flow to cyl

 

[supper plumb]

strip it to see if theres crud in the valve stopping it working

 

[AWheating]

probably wants cracking open/ adjusting alittle.

 

[lame plumber]

then strip it down anyway

 

[oz-plumber]

If possible, wire the 2 port valve to the pump wiring so the pump and the valve shut off at the same time.
If you can't wire the valve to the pump wiring, wire a run-on timer to the valve and keep the valve open for a period greater than the pump run-on timer.
That way the by-pass valve will hardly - if ever - be used.

 

[TerryWaite]

Thanks gents