New TRVs whistle when closing / opening

[jambo_sana]

Hi all, we recently had new radiators with new TRVs fitted. The new radiators are in different positions and the water is piped to the new positions with 15mm plastic pipes (the existing pipework is copper).

Some of the new TRVs whistle when closing / opening. When fully open (or fully closed, of course) they are silent. Here is a video of the sound: https://i.imgur.com/94ZaS9B.mp4

I have done the following:

- closed and slightly re-opened all the lockshield valves in the house (this was based on something I read online)
- switched TRVs between radiators, the whistling continues in the same radiators
- reduced the pressure in the heading system by letting water out
- bled all radiators multiple times

None of these things have made a difference. When closing the lockshield on the whistling radiators, the lockshield valve also whistles when almost closed. I have to open the lockshield valves on the whistling rads more than on others to stop that valve from whistling.

For reference, the old rads had standard (white plastic) TRVs, and the boiler has a built in bypass valve.

Is this a problem with the new TRVs? Not all the new valves (all same model) whistle. Or is it a problem with the plumbing itself - the length of the pipes to the radiators, etc?

Any help would be appreciated - I'm at my wit's end.

 

[cross thread]

Can happen when they or on the return pipe

 

[jambo_sana]

Can happen when they or on the return pipe

Thanks - definitely on the feed side, it's much hotter on the side with the valve

 

[muggles]

Pump speed is too high, and if you've messed around with the lockshields it's likely the system isn't correctly balanced either

 

[jambo_sana]

Pump speed is too high, and if you've messed around with the lockshields it's likely the system isn't correctly balanced either

It's a vaillant ecotec combi boiler, so I don't think I can adjust the pump speed? Or am I wrong?

Does the system balancing cause noise? As I said the noises were there before I turned any of the lock shields. And the system wasn't balanced before either, I think the heating is much more even now..

 

[muggles]

There are several models of Ecotec, will need more info than that (or a photo of the data plate on the bottom).

System balancing restricts the flow through the radiators which heat up first, the aim being to ensure the whole house heats up at the same rate. It also improves efficiency by setting the correct differential temperature across the radiator. Yes, it can cause noise if you're trying to force the water through a radiator at too high a flow rate.

 

[jambo_sana]

Thanks for the suggestion. Here is the information plate:

The manual is brief about pump speed.