Central heating pipes whistle when heating not being used

[james coutts]

I have a combi boiler, recently one radiator has started whistling , the heating is not on nor is the hot water being used ,I have done everything liking bleeding , cleaning and draining the whole system, checking the pressure in radiators, and changed the lockshields on the whistling radiator , which has a lockshield on both sides (no TRV ). When I removed the radiator to replace Lockshields the pipe from the floor continued to whistle while the radiator was not connected.. the whistle can go away for hours the comes back for no obvious reason...can anyone help ???

 

[chris watkins]

What is the tune ?

 

[chris watkins]

Turn of the incoming mains water James when it is doing it to see if it stops.
The filling loop is defiantly turned off fully, maybe disconnect to loop to check?

 

[james coutts]

What is the tune ?

Thank you Chris.

 

[james coutts]

have turned off mains water but still whistled, seems to be worse now and coming more often.

 

[Scott_D]

Turn off the power to the boiler
See if it stops

 

[james coutts]

have turned off mains water but still whistled, seems to be worse now and coming more often.

Turn off the power to the boiler
See if it stops

 

[james coutts]

power to boiler is off, but still whistles

 

[chris watkins]

What else is around the pipes or under the floor in that area?
Turn all the power off not just to the boiler.

 

[james coutts]

Hi Chris, I looked under the floor boards , all I can see is the copper pipes that are laid for the central heating, there is nothing on the wall except the radiator.

 

[james coutts]

Chris, something I have noticed, the whistle stops the longer the heating is on, when heating is turned off for at least 1 hour the whistle comes back again and will continue until I turn the heating back on.

 

[Last Plumber]

What Boiler is this?

 

[james coutts]

It is a Vokera h25 Combi Boiler

 

[Scott_D]

A pipe rubbing aginst something as it expands and contracts slowly?

 

[james coutts]

Hi Scott, I checked the pipes around the radiator and under the floor boards, nothing that I can see is touching anything