Identifying pipes.

[andy.pevy]

Hi

I am currently doing some plumbing in an extension and need to connect 'The old to the new'. There are 3 pipes running along the wall where I want to connect to, one is the incoming rising main, one is the hot to the downstairs cloakroom and the last is the cold to the cloakroom. Identifying the hot is obvious!!. But how could I tell the rising main from the tank fed pipe (they are all 15mm) without cutting them. I can isolate and drain the rising main but not the tank feed (well, not easily).

Anybody know any neat tricks please ???.

Andy Pevy

[Nigel Mercier ®]

The rising main will be colder than the pipe from the loft.

[Andrew McKay]

I was under the impression that all properties had a stopcock out in the road, or on the pavement outside the property. If you close that stopcock then you've stopped any water flow thru the rising main. Then as AP has suggested, screwdriver to the ear with the sharp end on the pipe(s) will reveal which pipe is allowing water to flow - from the tank.

Andrew

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[Brian]

Snipped

Hi Andrew,

Unfortunately not all properties have individual stop taps. It is possible that some older terraced houses could have only one external stop tap to the whole terrace and none on the insides of the properties (writing from personal experience) - which can cause any number of problems - especially if a neighbour is not at home when you turn the water off and then leave it off for a few hours. Others have perhaps one stop tap to three or four houses.

Brian

[Andrew McKay]

Thanks for clarifying - I hadn't realised that.

Though I suppose it is obvious that a high rise tower block wouldn't have a stopcock for each flat ;)

Andrew

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[Ed Sirett]

Generally blocks of flats have individual cuttoffs for mains cold, tank cold and HW (if communal). The only problem tends to be that in older blocks the cut offs are the original equipment and may no longer be serviceable.

As another poster has said pre-WWII terraced houses sometime don't have indiviual stop taps. This is true for one of the places I 'run'. I'm tempted to stop paying the bill and then watch how Thames Water would go about cutting the house off!!

[Ian Clowes]

Hi

As well as simple screwdriver tests...

The rising main will generally be consistently colder at this time of year than the tank in the loft.

Run a tap on the rising main, and you'll find the appropriate pipe feeling a little colder after a few seconds.

And if you care to mess around lots...

Attach a hose to the outlet from the tank _within_ the tank. Open the cold tap in the cloakroom and drain the pipes through. Now pour hot water down the tube and it'll run through to the cloakroom tap, heating the pipe as it goes. Might get an airlock though.

HTH IanC