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Plumberpro, Plumber
Category: Plumbing
Satisfied Customers: 634
Experience:  Heating and plumbing answers. 20 years experience
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problem with overflowing water from one of the tank in the

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problem with overflowing water from one of the tank in the loft. have two tanks in the loft, one small and the other large. small tank has ballcock to control the level of water. large tank does not have ballcock and therefore water overflows every now and then. there are some overhead pipes above the two tanks may be expansion pipes. the hot water tank is in the airing cupboard. have checked the level of water in the large tank it is just below the overflow outlet.
would like to know, why large tank has no ballcock, where the water comes from in the large tank and most importantly how do I stop the water overflowing from the large tank in the loft. please note that water overflows sometimes may be when the heating or hot water in on. I have not seen it overflow but I know that it does because I can see water marks on the outside wall.
Hi , does the large tank have any pipes coming in or out from the sides? Have you checked all around? Sorry to ask what may be the obvious ,but just trying to get my head around it
Customer: replied 2 years ago.

I can not remember. I will look in the loft this evening and update you.

Customer: replied 2 years ago.

Call me a stupid & I will not blame you. I made a mistake when I told you that the large tank in the loft did not have ballcock. I had a proper look just now and it does have a ballcock. I also found the cause of the water overflowing. The water keeps on dripping even when the ballcock is right up. I think that the washer or the valve must be faulty because the actual ball is okay.

So, can you advise me how to change the valve or washer so that the water is stopped dripping from the inlet feeder. I will have to shut off the water supply. How do I do this. Is this the mains water or can I shut the water from the valve next to the hot water tank.

Hi ,you will need to turn the mains water off at the stopcock .check its off with kitchen cold tap. Drain the tank by running hot bath tap to bring the water level down to make the job easier.Then undo the large nut that holds on the ball and ball arm. Take the washer off and replace with a new one.. If you can get someone else to turn the stopcock back on while you check everything is OK in loft , then that's always a good thing to do. Use a mobile to speak to each other as you do this. If on your own and you haven't done it before, turn the stopcock on for 10 seconds, check for leaks around ball valve, then turn water back on permanently and recheck.
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