Overflowing cold water tank

4 Feb 2006
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United Kingdom
Hi.My Mother recently had a new bathroom fitted that included an electric shower. Since this has been done the cold water tank in the loft has been overflowing during the night. I have replaced the ball valve and it is working normaly but I have noticed the pipe from the cold water tank to the hot water cylinder is back filling causing the said overflow. Is there a cure for this ! :rolleyes:
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The hot water cylinder is getting hot and is working OK but it is during the night when the hot water is not used that the overflow starts
i wouldn't of said it is an appliance backflowing etc as your not using any.
is it heated by boiler or immersion ?
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how longs it been doing it ?
and only at night ?
for how long and is it alot of water or dripping ?
It's been about 3 weeks, the reason it's happening during the night is the the hot water is been used through the day so the cold water tank does not have time to overflow
The cold water tank fills as normal from the ball valve, this is not the problem. the level of the water is correct and it does not overflow during day, but it happens at night because of the backflow from the hotwater cylinder. this is when there is no hotwater used eg washing the dishes ect
but to keep the level of water lower than the overflow alday you must have a constant tap on as you can bring a tank back up to its level even after a bath in under 15mins.
I think you have got the wrong end of the stick, there is no problem with the hot water or the the cold water tank filling. it fills as normal its hot water backflowing into the coldwater tank in the loft that is the problem. The reason it only happens at night is that the hot water is used during the day and the backflow from the hot water cylinder does no have time to do this. But as night there is no hot water used so the the backflow from the hot water cylinder fills the cold water tank to the point where it overflows
Are the new taps mixer taps (bath or basin) ?

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