Originally Posted by mikeysix
What is the central heating water quality like mate? The variance in whistling at the trv's may be due to the trv's being set at different temperatures. Some will be trying to slow the water flow down quicker than others due to room temp. If the seats of the valves are dirty then the venturi effect will be louder and might cause this whistling noise. Does the noise go away if you manually open or close the valve? Its just an idea mate.
The water quality looks quite good, it runs clear, slight yellow tinge i think due to inhibitor.
I think the whistling could be a mixture of poor quality terrier 2's and the pump speed on 3.
I'm just testing the pump on 2 at the mo, first day today as that could be causing the whistling and the air in the system as the water hits the impeller.
To top it off i think my flow and return pipes are connected the wrong way round on the boiler. As the temperature monitoring is attached to the return pipe by design (which is my flow pipe) this could be causing some of the short cycling.
Yes the noise does go when i adjust the valves. Bloody things wake me up in the morning, only option is to open them higher so they close a lot later.