Un-bonding solvent weld - sink waste pipe

[saudis]

Hi all,

I've fitted a new Belfast style kitchen sink over the weekend and in doing so have found that the waste pipe coming from the wall is roughly 1/2 inch to high to go into the P trap. Has anyone had a similar issue? I've managed to make the P trap connector watertight by using parts which don't actually fit together correctly with a considerable amount of silicon seal.

Has anyone made changes to there waste pipes, i.e. remove a couple of joints? I have attached a picture which shows the sink fitting and the waste pipe coming from the wall. I believe I could do with removing a couple of sections of the solvent welded waste pipe so that it's a couple of inches lower and would then allow me to fit a P trap without the current make shift joint. The challenge is I can't really see that I could cut the pipe as there are no straight sections for me to make a good joint onto. The wastepipe disappears into the wall and then is only see again outside where it joints the stack pipe.

Any advice appreciated...

Regards,


Steven.

 

[terryplumb]

Would a bottle trap not fit ?

 

[saudis]

Hi,

I did try a bottle trap but the problem was the same, the waste pipe is a 1/2 inch higher than the outflow from the bottle trap. What I thought would be a hours job took considerable longer running around trying different parts with the same outcome. If it was just a bit lower I could then make the connections secure and not reply on the silicon sealant keeping it watertight on a joint which isn't how it should be.

 

[m0t]

Solvent weld fuses the two bits of plastic together so you can't really 'un-weld' them. You could try cutting across the joint and then trying to split it off but it may not work.

 

[John D v2.0]

That setup is a right pain, best I can think of is either cut off hard behind the last fitting near the wall, clean up the pipe and maybe remove a little plaster, and start again from there.
Other option is to make your own diy trap out of suitable fittings, the only regs requirement is to be removable for cleaning, so as long as you get a couple of compression fittings in there and enough water seal you'd be ok.

 

[JimCrow]

 

[terryplumb]

Try wirquin Espace Extra Flat sink trap, tool station code 87482. This trap has the outlet virtually at the same level as the inlet. It also has a connection point for wash machine / dishwasher waste. If that don't fit the bill I would consider re tubing from outside ,could you cut the horizontal pipe that comes thru wall, outside. Then Inside incline all the pipework downward by rotating the section that comes thru wall. Then re connect outside ?

 

[Madrab]

Remake the outflow waste pipe, you know it makes sense.

 

[saudis]

Hi all,

Thanks for all the advice given.

I have a few ideas now which will hopefully resolve the issue with the least amount of risk or damage. John D, your suggest seems the most practical approach - unfortunately though the pipe is buried in an internal wall (must have been put in when built and not visible from the other side of the wall) and the only time it's seen again is where is leave the property and joins the stack pipe. I'm loathed to attempt putting in a whole new waste pipe especially with the risk of not being able to get at the pipe other than from under the sink - I really don't want an even bigger job!

It does surprise me though how it could have been put in so badly in the first place and still worked correctly. As mentioned it's "a right pain" of a setup and clearly not the first time that the problem has existed!

Steven.

 

[Dan Robinson]

Fernco

 

[cjcoffin]

If you make a lengthwise cut in the outer of one of the joints you might be able to introduce enough solvent to dissolve the existing weld line and then peel the joint apart a bit at a time adding more solvent as you go, leaving a stub you can weld a new fitting to. (Try it on one of the upper joints first.)

Alternatively what about using a 50mm universal compression fitting on the outer diameter of the joint? With some additional packing around the outside of the gasket you might get a reasonable seal. Then a reducer down to 40mm again. Not elegant but might work.

 

[Madrab]

The whole idea of a normal trap is to allow it to be removable and serviceable as well as forming a water seal to stop smell backing up into the room. If you make a homemade trap out of solvent fittings then it won't be serviceable, defeating the purpose of a removable sink trap. There looks as if there's enough of a tail of pipe sticking out of the wall to cut at the elbow collar and then fit a new fitting.

I don't see what the issue is .... It's an easy diy fix. Fit it all dry with the new waste trap on and in, pencil mark up the joints and then glue.

 

[Hugh Jaleak]

Would the McAlpine trap fit? https://www.screwfix.com/p/mcalpine-tubular-p-trap-white-40mm/75915

 

[Nige F]

Hi all,

. The wastepipe disappears into the wall and then is only see again outside where it joints the stack pipe.





Steven.

So it's hidden in the wall for a distance Is the wall hollow/ plasterboard? If so you could enlarge the hole and get some movement on the pipe

 

[picasso]

As dan suggested a fernco would do this, cut the pipe off at the bottom elbow and slide a fernco over the old elbow stub, inch and a half would fit over the old elbow.