Help - overlow leaking from coldwater tank.

I'm getting quite a significant leak coming through the overflow in the coldwater tank - started about 2-3 weeks back. The tank is in the loft, hot water cylinder (about 18 months old) on the 1st floor & boiler (about 20 years old) on the ground floor. I swapped the ballcock out (about the limit of my expertise), which made no difference. Had a plumber around who did exactly the same thing & again no difference. I had a closer look & realised that water is coming back up from the pipe that feeds the hot water tank & the cold water tank actually contains warm (ish) water. The plumber is now suggesting that I replace the boiler (it's old but still kicks out a lot of heat), although he doesn't seem convinced that it will cure the problem - any suggestions please ? One thing I did spot whilst I was rooting about is that there's no thermostat on the hot water tank, which doesn't feel right to me ? The hot water tank was installed by the same plumber. I don't mind getting the professionals in to do the job, but would like a second (or third) opinion, as I've lost confidence in the professionals I've used to date. Thanks for your time

Reply to
Ian Whittaker
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Is there a central heating header tank (a small one) and is it higher than the cold water tank? Is its float valve letting in water at the same rate the overflow is running? If so you have a leak in the coil in your hot water cylinder.

Reply to
John Stumbles

Another possibility (though unlikely) might be that there's no non-return valve on a shower or tap somewhere in the house.

When something like a tap/shower has both a hot and cold water feed the non-return valve prevents the higher pressure mains fed water from pushing back up the lower pressure hot water feed.

Andrew

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Reply to
Andrew McKay

A bit more info - I've checked the central heating header tank - it appears to be about the same height as the cold water tank & there's definitely no water running in or out of it - checked the ballcock for the central heating tank & it seems to be working fine. Also tried switching the hot water off for 24 hours - leak still persisted after all of the hot water had ran out. Someone mentioned a return valve on a tap - would this apply for mixer taps ? the bathroom has 2 of them & an electric shower with both hot & cold feeds (incidentaly all installed about 18 months ago by the usual plumber). All the plumbing in the bathroom is fairly modern (18 months old) & fairly old through the rest of the house. A bit more info - I've also noticed that occassionally when I turn the sink tap (it's a mixer) on to hot in the bathoom, the whirlpool pump for the bath switches on for half a second or so - the on/off switch is on the bath surround & uses air pressure. It sounds like the problem might be linked ?

Reply to
Ian Whittaker

What kind of heating system do you have, does the domestic hot water have any foam or strange smell? Tie up the ball c*ck for the CH and see what happens.

Reply to
James Salisbury

Ok - tied the CH ballcock up for 24 hours & nothing happened - water levels still as before, so I'm pretty sure nothing's coming through that route. Hot water looks fine - even had a go at drinking it after it had cooled down & it seemed normal. We've got a fairly old gas fired, floor standing boiler in the kitchen, gas central heating, a hot water cylinder in the bathroom & 2 tanks in the loft - small one for Ch & larger (leaking one) for cold water.

Reply to
Ian Whittaker

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