leaky overflow problem

[forthright mc]

our overflow pipe has been leaking a lot of water for the past few days, a lot more than normal even the neughbors have noticed it. my initial theory was a ballcock problem in the tank in the loft but apparently it could be something else.
anyone got any ideas what could be causing this constant stream of water? it only stops when i leave the tap running in the bath. any help would be greatly appreciated before i have to get a plumber in.
cheers

[dirkgently]

Annulus in the H/W cilinder has a hole in it

[mattley]

forthright mc said:

my initial theory was a ballcock problem in the tank in the loft but apparently it could be something else.

What makes you think it could be something else? Most overflows are ball valve related. Have you checked the ball valve in the header tank?

[simpo two]

Leaving the tap running is reducing the head of water in your cold water tank. Hence I'd say your main stopcock is stuck/has some grit in it.

[father ted]

usually there is an adjustable screw where the water high level shut off valve actuates.....generally speaking ,if you screw this out the water high level shut-off will operate earlier as the ball cock rises and the level should then not reach the overflow pipe

trial and error adjustments time!

[dirkgently]

mattley said:

What makes you think it could be something else? Most overflows are ball valve related. Have you checked the ball valve in the header tank?

Your right, but I’m a plumber I love to talk a job up

[forthright mc]

cheers for the replies guys!
going to get someone to look into it hopefully it won't be too expensive!!

[NiceCupOfTea]

I had this a while back and it was the ballcock in the toilet needing adjusting.