Whistleing Radiators

I've recently installed some TRV's on a few of my radiators, but when the temperature is just below the shut off point they seem to start whistleing! It seems to be on every radiator so it's not just a rouge TRV.
I fitted the Pegler Terrior II TRV's from Screwfix as I was told Pegler was a reputable make. Could anyone shead any light onto why this is happening and if there's a solution (apart from replacing them all!).
On the bright side, it does negate the need for an alarm clock in the morning!
Cheers Phil
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On 5 Dec 2003 04:48:49 -0800, snipped-for-privacy@philandjo.co.uk (Big Phil) wrote:

Seriously though, have you balanced the system or are all the lockshields wide open?
Otherwise you are asking the TRVs to do the entire flow control.
If the pump is on a high setting, creating high flow/pressure then the valves could whistle as they are shutting off. Try reducing the pump setting.

.andy
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I'd recommend fitting an automatic bypass valve, or setting up the one you already have. This can substantially reduce issues like this. Another possibility, if you have a pump external to the boiler, is to replace by an intelligent pump such as a Grundfos Alpha, that notices TRV shut down and slows down automatically, rather than putting ever faster water through the radiators still on, causing excessive noise.
Christian.
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Big Phil wrote:

I fitted the same ones to a new combi boiler system. Haven't noticed any noise ....
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Thanks for all these. I am planning on moving to a Combi System in the very near future, the TRV's on some of the rads were the first phase of this, so I'll see what it's like afterwards. In the meantime I'll balance them a bit better as they are currently all fully open I think.
Thanks again, what a useful newsgroup this is. Phil
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