Pipe fills with water when its shut off

[Boyd]

Hi All, I'm attempting to replace a feed pipe going into my toilet cistern. Seems like a straightforward job? The top part was in ugly plastic (the bit I wanted to replace) joined to copper pipe. So, I made up the pipework (solder ring joints - all good so far) then should be easy to connect this pipework to the existing copper using another solder ring connector, except that the pipe keeps filling with water so the solder will not run. Arghh!!!!
The gate valve from the cold water tank is turned off and no water is coming from the non-mains cold taps and none was going into the cistern before removing the old pipework but now every minute or so the pipe fills up with cold water. I've syphoned it out but soon comes back. Where is it coming from? The hot water runs off a hot water tank fed from the cold water tank with its own gate valve. This valve is still open but the taps are closed so I can't see that there could be any back-flow through a mixer tap from the hot to the cold pipework. Any ideas anyone? Any plumbers out there that can advise? Thanks

 

[seco services]

you sure the gate valve is not letting by.

 

[Softus]

seco is right - if water is flowing then the GV is not shutting off.

If you absolutely have to do with soldered copper, then start by adding an isolating valve so that you have control.

A job like that would take about five minutes if you did it with plastic pipe and push-fit fittings.

 

[AMEdinburgh]

Just a thought. If your gate valve is almost closed but not quite, you might get way with leaving open the other cold taps in the house so any water seeping past the gate valve has somewhere else to go. Might allow you finish this part of the job
(diyer not plumber though!)

 

[Boyd]

I've shut the gate valve as far as possible but I suppose it could be letting by (I think GVs are prone to this?). I'm only wanting to do this in soldered copper as I've been used to this in the past, its fairly simple (normally) and robust but I may look to do it in push-fit copper perhaps (I suppose this would work?). Plastic is what I'm replacing due to it joining onto copper so all in copper would look better (and the plastic looked so tacky (though I expect there is better plastic than the bit fitted in my house).

 

[Boyd]

And Thanks AM, good suggestion. I may try turning on the upstairs cold taps (or may take the easy(?) option now of push-fit copper. I'll decide tomorrow!)

 

[Softus]

You could do it in white-coloured Speedfit, or in grey Hep2o and then paint it white.

 

[powell30]

All good suggestions from the lads......one more. Turn off mains. Drain cw tank and replace the gate vale.....then try to do your work.

 

[AMEdinburgh]

If leaving a tap(s) open whilst you work, one would need to be below the height of the WC pipe i.e. downstairs.

 

[AlanE]

Or let the pipe fill with water and then freeze it above where you are working.

 

[Boyd]

Good suggestions Thanks. I'm still leaning towards using copper push-fit though the freezing of the pipe sounds a good way. I've never done that before, is it easy to do? Presumably I can buy the freezing stuff easily?

 

[lagunaglen]

Just fit an isolation valve on the pipework and all your problems are solved.

 

[Softus]

Good suggestions Thanks. I'm still leaning towards using copper push-fit though the freezing of the pipe sounds a good way. I've never done that before, is it easy to do? Presumably I can buy the freezing stuff easily?

Jesus H. Christ on a bike.

I can't imagine why you're making things so complicated. You don't need to freeze anything, unless you just fancy wasting £10 to find out how to do it.

S*d the soldering, just buy a metre of Hep2o, one tap connector, one elbow, one coupling, and four sleeves, and whack it all on before we all die. If you don't trust the existing means of isolation then use a service valve instead of the coupling.

FFS.

 

[Boyd]

Well Softus you don't really need to look at these posts if you're that fed up I'm sure you have other things you could be doing. I think I've already said that I don't like the look of plastic.
Thanks to the others for their help.

 

[Softus]

Well Softus you don't really need to look at these posts if you're that fed up I'm sure you have other things you could be doing

Well Boyd you don't really need to look at my posts if you're that fed up. I'm sure you have other things you could be doing, like staring at water coming out of an open pipe, or wasting your money on a freezing kit.

I think I've already said that I don't like the look of plastic.

In that case buy a metre of 15mm copper tube, one brass swivel tap connector, one Tectite elbow, one Tectite coupling, some PTFE tape, and whack it all on before we all die. If you don't trust the existing means of isolation then use a chrome-on-brass ball-o-fix valve instead of the coupling.

FFS.