Loud groaning from the cold water system.

[langtounboy]

I was woken up last night with a loud groaning noise coming from the cold water system . It went on for over a minute and at 02:00 I could imagine that the neighbours would be a little peeved. I managed to make the noise quieter by turning on the mains pressure tap in the kitchen but it still didn’t eliminate the noise completely. It doesn’t sound like water hammer but I think it may be air trying to escape from the system. Any ideas where I should be looking.?

 

[tryitandsee]

Does it continue to make this noise when you turn off the main stop cock.

If not, first thing to check would be the float valve in tank. Some times they make a noise in the last moments of filling, causing various vibrations/noise. Don't waste time renewing bits, just get a new one complete, as they are not that expensive.