Noisy TRVs

[BAZ53]

I have a problem with water hammer when 2 of my rads TRVs shut down.
Both rads are on the 1st Flr end of the pipe run.
There,s a total of 6 rads all have TRVs. The system must be 20 years old.
Open vented , gravity hot water. Rads and valves 1 year old,no problems with air in the system.
TRVs are reverse flow.

Any thougths or ideas.

Thanks

 

[gas4you]

Faulty trv's, even biflo ones can cause water hammer, which is why Danfoss brought out the revolver ones, so you can change their direction by 'twisting the guts' in the valve.