Cold water overflow pipe dripping, some mornings

3 Oct 2008
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United Kingdom

I would appreciate some advice please.

Basically, the overflow pipe from the cold water tank in the loft (I think) is dripping sometimes. We wake up (7-8am) some mornings to find a puddle on the ground under the overflow pipe from the loft. The water is splashing up on the wall so it must initially be running out but we have only ever seen it drip. The drips get less frequent over an hour or so until they stop altogether. This only happens about once a week or so.

So, what could be causing this. I know that dripping can be caused by a faulty valve in the ball cock but the drip is not constant so I'm not sure if it is the valve. It seems to happen around the same time the gas central heating comes on but again that comes on every morning.

Any help would be gratefully appreciated.

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Could be a faulty ball valve letting by over night when the pressure is higher. As it happens as the heating is starting it may be expansion of hot water in the cylinder causing the level to rise slightly in the cold water storage cistern. The level in the cistern should be low enough to accommodate this expansion. If the level in the cistern is too high the ball valve may just need adjusting or it may be faulty.

Before you run off any water in the morning go up and have a look. If the float is partially submerged there is a fault. Check the float is not partially full of water, if it is intact the ball valve is letting by and needs refurbishment/replacement.
as swbjackson, i would agree its the ball valve letting the smallest drip bye,till it gets to the point when it gets near overflow conditions the expansion of the dhw will cause the overflow.
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Thanks to you both for your helpful replies.

Guess I'll be getting a new ball valve then!

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