HELP - Back to back WC's issue with cross flow

[Milan5baros]

Morning all,

Struggling to resolve a problem. Back to back WC's in a fourth floor flat and the waste from toilet A(main bathroom) transfers into toilet B (ensuite) we have installed the McAlpine ARB 1 anti-cross flow valve on each side but it has only stopped solids and there is still some fluid getting through.

I have attached images of how this looks. How would you advise we fix this?

Appreciate any advice.

Many thanks,
Jack

 

[Clint B]

Sorry to say not easily. Both outlets would ideally drop in a near horizontal float to the stack. It was refreshing to see he has used a 45 branch but it is so close to connecting we you are asking for problems. Not straight forward to recover from.

 

[Ben-gee]

If you can, lower the branch on the stack - but it looks as though you can’t.

If you can’t lower it.

Change the branch to a double corner branch and run each wc separately back to it (this is one where the two branches are at 90 degrees instead of the more usual 180.

I’m assuming as it’s a flat you can’t drop one of them through the floor and connect to the stack lower down - you could if the services all run in a common, accessible cupboard as they sometimes do......

 

[snowhead]

Especially given the 45 branch and it's distance from the ensuite pan, I'd say there's a partial blockage in the branch pipe (with the white collar) or in the stack if there are no flats higher.

There would have to be quite a build up to get fluids to flow back to the Ensuite pan.
I think I'd cut a rodding eye into the branch near the stack junction to watch the water flow when flushed.
It may be usefull in the future if there's any blockages.

 

[Stigster]

I think you could well be right as assuming the toilets were not going to be put elsewhere, the plumber has done the right thing and the best they can given the setup. I would have not expected any noticeable cross flow looking at how it's been connected up.

 

[Milan5baros]

uming the toilets were not going to be put elsewhere, the plumber has done the right thing and the best they can given the setup. I would have not ex

If you can, lower the branch on the stack - but it looks as though you can’t.

If you can’t lower it.

Change the branch to a double corner branch and run each wc separately back to it (this is one where the two branches are at 90 degrees instead of the more usual 180.

I’m assuming as it’s a flat you can’t drop one of them through the floor and connect to the stack lower down - you could if the services all run in a common, accessible cupboard as they sometimes do....

Do you mean like this one? Seems a good idea! hmmm

 

[MOSSEP]

Is there much fall on the horizontal pipe? Sounds like isn't flowing away correctly, especially if you were having solids go back into the pan.

 

[Ben-gee]

Yes that’s the fella, I have used one once before and it got me out of a tricky situation very nicely.