Noise in oneway valve/pipe work in central heating system

[dkearns946]

Hi,
I have a central heating system which is a sealed unvented (pressurised) system (Gloworm/RCM cylinder) which is making a continuous noise whilst the pump (Grundfos) is on and running.

I have replaced the pump under warranty, which helped to reduce the noise level..

Now the remaining noise appears to be coming after the pump, the pipe work flowing INTO the cylinder through a one way valve. When you put a screwdriver against the pump/pipe to listen to the vibrations it is sounding quite, but 1 foot later the same pipe & one way valve connecting to the cylinder is where the noise seems to be coming from. (the flow into the cylinder)

The one way valve into the cylinder is a sealed unit, is it possible some sort of dirt is in the way causing the noise, is it worth flushing the system, or replacing the valve?

I notice now that when a tap is on running hot water the noise goes away, but the minute the tape is off, it comes back...

The system was newly installed with Fernox in Nov 2004. If I reduce the speed of the pump to setting 1 it does help.
I have tried bleeding the air from the pump when you turn it off & on, no change....it still seems to be from the one way valve/pipe.

Any ideas?

Dave

 

[doitall]

One has to ask what a check valve is doing on the primary circuit.

If the primaries are sealed an additional expansion vessel must be fitted.

Has the pre-charge in the expansion vessel been set at 3bar.

Was it installed by a plumber with an un-vented ticket and did he fill out the log book.

 

[ChrisR]

Considering

I notice now that when a tap is on running hot water the noise goes away, but the minute the tape is off, it comes back...

I wonder if it really is on the primary (boiler circuit).

 

[holty]

is the pump you have a bronze one. like chris r is getting at. could be a circulating pump for the secondary return for the hot water

 

[dkearns946]

One has to ask what a check valve is doing on the primary circuit.

If the primaries are sealed an additional expansion vessel must be fitted.

Has the pre-charge in the expansion vessel been set at 3bar.

Was it installed by a plumber with an un-vented ticket and did he fill out the log book.

Hi,
I have not seen a oneway valve before on a conventional system, so was not sure if it was required for a unvented sealed system.
Th valve indicates it is set to 3bar.