Isolating the supply to downstairs toilet

Hi,

A question on isolating valves and draining them -

I have a simple downstairs WC and recently I noticed that the wood boxing hiding the pipework had begun to go mouldy. I removed everything and it was clear that something had been leaking behind the toilet system.

I think it is the isolating valve as the dampest point seems to be surrounding it.

I've attempted to shut off the water system using the shut off valve under the sink. It shuts the kitchen and upstairs bathroom taps off almost instantly but the tap in the WC needs to be run for about 30 seconds before it shuts off. The water supply to the isolating valve does not seem to turn off, I have not yet tried to drain it as I'm worried it will continually flow!

All help appreciated.

Does the pipe come down from the ceiling?

If so, when you turn off your stop tap, even though you have isolated the water, there is still all the water in the pipework to drain out too, so until the pipework is empty you will get water out.

Once the stop tap is off, drain the cold as you say from the downstairs bathroom tap until it ceases to run, then crack the compression on the isolating valve to the toilet, drain any water in that leg of pipework ( if any) into a bucket, then you should be good to go ahead and change it.

Thanks for your advice.

The water is fed from upstairs. I'll give it a go and let you know how I get on. Thanks again.

2 things, if you can get the top of the cistern off you could operate the filling valve after turning the supply off this will allow water in the pipe to flow from upstairs hopefully emptying it or at least reducing the amount which comes out when you do the isolating valve. Secondly if the valve is boxed in and is colder that the room its in then you could have a condensation problem, with the water forming on the valve being the biggest cold lump.

hi1 said:

2 things, if you can get the top of the cistern off you could operate the filling valve after turning the supply off this will allow water in the pipe to flow from upstairs hopefully emptying it or at least reducing the amount which comes out when you do the isolating valve. Secondly if the valve is boxed in and is colder that the room its in then you could have a condensation problem, with the water forming on the valve being the biggest cold lump.

Click to expand...

What are you on about, did you post this in the wrong thread?

John try reading what i've written, i realise reading is not a known skill in your part of the world, then think about that in the context of the the OP's post.

The fill valve in the toilet cistern is the lowest part of the circuit down stream of the isolating valve, if the mains supply is off at the mains, operating it manually will allow it to act as a drain off valve, the water being in pipes above it, as posted by the OP, will run down hill subject to gravity, at least it does in this part of the world. Hopefully this will drain off enough water so that when the OP does whatever with the isolating valve the water level will be below the valve thus not leaking when disconnected.
If you have something boxed in which is colder than the surrounding air condensation can form on it, water, in sufficient quanities this can lead to the appearance of damp. The OP states the valve and presumably the cold water feed to the cistern is boxed in, this can lead to a localised temperature difference, the pipes and valve will be colder than the air in the room the toilet is in giving rise to this problem.