Cold Water Tank Filling even with stopcock tied off

[samurai69]

We have a large cold water tank and even with the stop cock tied off so no water can come through that point the water is still feeding into the tank somehow

i drained 4 or 5 buckets out of it and made sure no water was coming through from the stopcock tap and it still filled up after a short time, i cannot see any other water pipe apart from the one at the bottom that i assume feeds to all the toilets etc

 

[leakydave]

Do you have a second smaller water tank that feeds the heating system? If so and it is higher than the CWSC then the coil in your cylinder may be passing water [leaking] from heating system to hot water system...
or...

You have a mixer tap that could be passing cold mains water back into the hot water system.

 

[FiremanT]

As per Dave: look at the pipes feedingany mixer taps. Condensation is a good indicator, but maybe too warm at the the moment.

 

[samurai69]

not that i can see.

turned the tap off from the bottom pipe and there is now no water coming in, so I'm assuming there is some sort of feed in the bottom pipe, which i assumed was a drain away pipe that feeds the toilet cysterns

 

[leakydave]

The water is either coming in from the cylinder coil or a tap/shower that is passing cold water into the hot water system.

 

[FiremanT]

Have you actually read the previous responses? You have turned off an isolation valve, which is there to stop the flow FROM the CWS. In this case it is also stopping the errant flow from reaching the CWS.

How lucky are you? If unlucky, you may find that when you turn the valve back on, the gate will be left in the closed position.

 

[mogget]

I think the cwsc stopping filling when cold feed is isolated, would rule out a passing mixer. Reason being that unless someone's made a big mistake it would find its way up the vent pipe instead after a while? It implies that the source of the water is not at a high pressure.

 

[leakydave]

The passing could come from a very small flow from the cold into the hot I have seen it before.

 

[Dan Robinson]

Reason being that unless someone's made a big mistake it would find its way up the vent pipe

That would mean an even bigger mistake

 

[mogget]

D'oh! Didn't read the post properly. Misread stopcock as ballcock.

For punishment I have the flu.