Banging in the cold water pipes - NOT water hammer.

[ponyboy]

Hi guys, first post, hope you can help.

We recently purchased a flat and have a problem with the cold water tap in the bathroom. When you turn it ON there is a whine that grows louder until it turns into a banging in the pipes, this disappears once the tap is turned on further. It doesn't happen if there is a tap on else where in the flat, or even if the hot tap is on in the bathroom. I think there's air in the system, but haven't really got a clue, it's just an uneducated guess. :p

The system is a combi boiler, about 3 years old. I say it's not water hammer as that is shuddering when taps are turned off, not on as this case.

Any ideas? Muchos graciass. :D

[ALDA]

P,

AN EDUCATED GUESS, COLD WATER PIPE IS UNSUPPORTED!

THERE IS A POINT WHERE THE FORCE OF WATER THROUGH THE PIPE WILL MAKE IT VIBRATE.

(RATTLING AGAINST SOMETHING)

A.