Hot water from cold tap!

[notarealplumber]

I am attempting two jobs in an ensuite bathroom. They both involve turning off the cold water supply. As far as I am aware the cold water feeds from the loft based tank (interestingly, made of slate).
I have turned off three different taps:-
1) Stop cock.
2) Feed from the tank in the loft.
3) A tap that comes from the top of the hot water cylinder.
The result is that the hot water stops coming out of the hot taps in the bathroom but hot water starts coming out of the cold tap after a minute or so.
Is this possible? Well I know it's possible, but why does it do it?

 

[ChrisR]

Tap on cyl doesn't work (gate valves often don't) and you have a faulty mixer tap somewhere.

 

[TicklyT]

I've seen this before - someone had teed from the cold feed to the hot cylinder after the gate valve to feed a basin cold tap. Turn off the gate valve, and the cold tap drains the hot cylinder, the cold water in the bottom first, gradually getting hotter as the cylinder drains.

Edited spelling

 

[pannierstan]

Do you have a shower that works off the hot water system?

Stan

 

[notarealplumber]

Thanks for the replies above. I think the Tickly T has the answer. We had an ensuite built when we moved in 19 years ago. I am jsut surprised that we have not had the need to chage a washer on the cold taps in that time. Looks like the hot water has to be drained. Never mind. Thanks gents.